U.S. patent application number 12/340207 was filed with the patent office on 2009-06-25 for hybrid vehicle systems.
This patent application is currently assigned to EnVont LLC. Invention is credited to James Joseph DeLuca, Gary D. Tucker, II.
Application Number | 20090163656 12/340207 |
Document ID | / |
Family ID | 40789402 |
Filed Date | 2009-06-25 |
United States Patent
Application |
20090163656 |
Kind Code |
A1 |
DeLuca; James Joseph ; et
al. |
June 25, 2009 |
HYBRID VEHICLE SYSTEMS
Abstract
A hybrid film-forming composition is prepared by forming an
aqueous mixture including an organofunctional silane, a metal
chloride, and an acid, and boiling the mixture. A base is added to
the aqueous mixture to substantially neutralize the mixture and to
form a hydroxide of the metal. A colloidal suspension including the
metal hydroxide and a siloxy compound is formed. A peroxide-based
solution is added to the suspension to form a suspension including
a peroxide of the metal. The suspension is allowed to equilibrate
at room temperature. The suspension is boiled at a pressure greater
than atmospheric pressure to form a hybrid film-forming composition
including the condensation product of a siloxy compound and a metal
peroxide. A coating formed from the hybrid film-forming composition
may be hydrophobic or hydrophilic.
Inventors: |
DeLuca; James Joseph;
(Parma, OH) ; Tucker, II; Gary D.; (Manchester,
CT) |
Correspondence
Address: |
FISH & RICHARDSON P.C.
P.O BOX 1022
Minneapolis
MN
55440-1022
US
|
Assignee: |
EnVont LLC
Naples
FL
|
Family ID: |
40789402 |
Appl. No.: |
12/340207 |
Filed: |
December 19, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12202076 |
Aug 29, 2008 |
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12340207 |
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12167863 |
Jul 3, 2008 |
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12202076 |
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11963380 |
Dec 21, 2007 |
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12167863 |
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Current U.S.
Class: |
524/837 ;
427/387 |
Current CPC
Class: |
C01G 23/053 20130101;
C08K 2003/0881 20130101; C09D 1/00 20130101; C09D 7/61 20180101;
C09D 7/63 20180101; C08K 3/08 20130101; B01J 13/0039 20130101; B01J
13/0047 20130101; C08G 77/58 20130101; B01J 13/00 20130101 |
Class at
Publication: |
524/837 ;
427/387 |
International
Class: |
B05D 3/10 20060101
B05D003/10; C08G 77/10 20060101 C08G077/10 |
Claims
1. A method of preparing a composition comprising: (a) forming an
aqueous mixture comprising: (i) an organofunctional silane; (ii) a
metal chloride; and (iii) an acid; (b) boiling the aqueous mixture;
(c) adding a base to the aqueous mixture to substantially
neutralize the mixture and to form a hydroxide of the metal; (d)
forming a colloidal suspension comprising the metal hydroxide and a
siloxy compound; (e) adding a peroxide-based solution to form a
suspension comprising a peroxide of the metal; (f) allowing the
suspension to equilibrate at room temperature; and (g) boiling the
suspension at a pressure greater than atmospheric pressure to form
a hybrid film-forming composition comprising the condensation
product of a siloxy compound and a metal peroxide.
2. The method of claim 1, wherein the pH of the aqueous mixture in
(a) and (b) is less than 1.
3. The method of claim 1, wherein the aqueous mixture formed in (a)
further comprises an organofunctional silane.
4. The method of claim 1, wherein the composition formed by boiling
the suspension further comprises crystalline particles less than
about 10 nm in diameter comprising a hybrid metal oxide.
5. The method of claim 1, wherein the film-forming composition
comprises the condensation product of a siloxy compound and a
transition metal peroxide.
6. The method of claim 1, wherein the organofunctional silane is
selected from a group consisting of bis(triethoxysilyl)methane,
1,1,3,3-tetramethyl-1,3-diethoxydisiloxane, and
octochlorotrisiloxane, tetraethoxysilane, or any combination
thereof.
7. The method of claim 1, wherein the metal chloride comprises a
chloride of silicon, titanium, zirconium, tin, vanadium, gallium,
germanium, tellurium, hafnium, rhenium, iridium, platinum, or any
combination of two or more chlorides of silicon, titanium,
zirconium, tin, vanadium, gallium, germanium, tellurium, hafnium,
rhenium, iridium, or platinum.
8. The method of claim 1, wherein the metal chloride is a metal
tetrachloride.
9. The method of claim 1, further comprising applying the hybrid
film-forming composition to a substrate and drying the composition
to form a coating on the substrate.
10. The method of claim 9, wherein the coating is hydrophilic.
11. The method of claim 10, wherein a contact angle of water on the
coating is less than about 10.degree..
12. A composition prepared according to the process of claim 1.
13. A composition prepared according to the process of claim 2.
14. A coated substrate prepared according toe the process of claim
8.
15. A process for preparing an article comprising: (a) providing a
composition comprising: (i) an aqueous carrier; and (ii) the
condensation product of a siloxy compound and a metal peroxide; (b)
applying the composition to a surface of a substrate; and (c)
removing the aqueous carrier to form an article comprising a
siloxy-peroxy hybrid metal coating on the surface of the substrate,
wherein the coating is hydrophilic.
16. The process of claim 15, wherein the composition further
comprises crystalline particles with a diameter less than about 10
nm comprising a hybrid metal oxide.
17. The process of claim 15, wherein the composition further
comprises crystalline particles with a diameter less than about 10
nm comprising a metal oxide.
18. The process of claim 15, wherein a thickness of the coating is
less than about 10 nm.
19. The process of claim 15, wherein the coating is covalently
bonded to the surface of the substrate.
20. The process of claim 15, wherein a contact angle of water on
the coating is less than about 10.degree..
21. A process for preparing an article comprising: (a) providing a
composition comprising: (i) an aqueous carrier; and (ii) the
condensation product of a siloxy compound and a metal peroxide; (b)
applying the composition to a surface of a substrate; and (c)
removing the aqueous carrier to form an article comprising a
siloxy-peroxy hybrid metal coating on the surface of the substrate,
wherein the coating is hydrophobic.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation in part of U.S.
application Ser. No. 12/202,076, filed Aug. 29, 2008, which is a
continuation-in-part of U.S. application Ser. No. 12/167,863, filed
Jul. 3, 2008, which is a continuation-in-part of U.S. application
Ser. No. 11/963,380, filed Dec. 21, 2007, all of which are
incorporated by reference herein in their entirety.
TECHNICAL FIELD
[0002] This invention relates to aqueous hybrid metal oxide
polymeric vehicle systems.
BACKGROUND
[0003] Photocatalytically-active, self-cleaning aqueous coating
compositions and methods are known in the art. Compositions
containing a metal peroxide have been used to form clear, colorless
adhesive coatings on substrates, including micro particulate
substrates. Coating compositions with nanoparticles have been used
to bind the nanoparticles to a substrate.
SUMMARY
[0004] In one aspect, a composition includes an aqueous carrier and
the condensation product of an organofunctional silane and a
transition metal peroxide. In certain implementations, the
composition includes crystalline nano-sized particles. The
nano-sized particles include a transition metal oxide. At least
some of the nano-sized particles are less than about 10 nm in
diameter. In some embodiments, the transition metal of the
transition metal peroxide is the same as the transition metal of
the transition metal oxide. The transition metal can be selected
from the group consisting of titanium, zinc, and combinations
thereof.
[0005] In some implementations, the composition includes an
additive selected from the group consisting of an organometallic
compound, a wetting agent, an organic compound, a metal, and
combinations thereof. In some cases, the composition includes a
filler. The filler can be substantially inert. The filler can
include, for example, carbon nanotubes. The weight of the filler
can be greater than the weight of the transition metal in the
composition.
[0006] In another aspect, a process for preparing a composition
includes providing a first mixture, and boiling the first mixture
at a pressure greater than atmospheric pressure to form a
composition. The first mixture includes an organofunctional silane,
a transition metal peroxide, and an aqueous carrier. The
composition that is formed includes the aqueous carrier and the
condensation product of the organofunctional silane and the
transition metal peroxide.
[0007] In some implementations, the composition formed by boiling
the first mixture at a pressure greater than atmospheric pressure
further includes crystalline nano-sized particles. The nano-sized
particles include a transition metal oxide. At least some of the
nano-sized particles are less than about 10 nm in diameter. In some
cases, the first mixture includes at least one additive selected
from the group consisting of an organometallic compound, a wetting
agent, an organic compound, a metal, a metal salt, a filler, and
combinations thereof. The first mixture can be in the form of a
colloidal suspension. The organofunctional silane may be, for
example, bis(triethoxysilyl)methane,
1,1,3,3-tetramethyl-1,3-diethoxydisiloxane, octochloro-trisiloxane,
tetraethoxysilane, or any combination thereof.
[0008] In certain implementations, the process further includes
combining an aqueous solution including a peroxide with a colloidal
suspension including an amorphous metal hydroxide in an aqueous
carrier to form a colloidal suspension. The colloidal suspension
includes the transition metal peroxide. The process can also
include combining a transition metal salt and an acid with an
aqueous carrier to form a second mixture, substantially
neutralizing the second mixture, filtering the second mixture to
form an amorphous metal hydroxide, and suspending the amorphous
metal hydroxide in an aqueous carrier to form the colloidal
suspension.
[0009] Other implementations include compositions prepared
according to the above-described processes.
[0010] In another aspect, a process for preparing an article
includes providing a composition including an aqueous carrier and
the condensation product of an organofunctional silane and a
transition metal peroxide, applying the composition to a surface of
a substrate, and removing the aqueous carrier to form an article
with a coating on the surface of the substrate. In some
embodiments, the coating is removed from the substrate to form
nano-sized particles in powder form.
[0011] In some implementations, the composition includes
crystalline nano-sized particles. The nano-sized particles include
a transition metal oxide. A thickness of the coating can be less
than about 10 nm. The coating is covalently bonded to the surface
of the substrate. In some embodiments, the substrate is porous. In
certain embodiments, the substrate is particulate.
[0012] In one aspect, a composition includes an aqueous carrier and
the condensation product of a silicon peroxide and a transition
metal peroxide. In another aspect, preparing a composition includes
providing a first mixture, and boiling the first mixture at a
pressure greater than atmospheric pressure to form a composition.
The first mixture includes a silicon peroxide, a transition metal
peroxide, and an aqueous carrier. The composition that is formed
includes the aqueous carrier and the condensation product of the
silicon peroxide and the transition metal peroxide. In another
aspect, preparing an article includes providing a composition
including an aqueous carrier and the condensation product of a
silicon peroxide and a transition metal peroxide, applying the
composition to a surface of a substrate, and removing the aqueous
carrier to form an article including a hybrid metal oxide coating
on the surface of the substrate.
[0013] In certain implementations, the composition includes
crystalline particles less than about 10 nm in diameter. The
particles can include a hybrid metal oxide, a transition metal
oxide, or a combination thereof. The composition can include
silicon oxide and transition metal oxide. A weight percentage of
the silicon oxide, based on total metal oxide, can be at least
about 50 wt %, at least about, 95 wt %, or at least about 99 wt %.
A weight percentage of the transition metal oxide, based on total
metal oxide, can be at least about 95 wt %. In some cases, the
condensation product includes silicon, titanium, zirconium, or any
combination thereof in some implementations, the composition formed
by boiling the first mixture at a pressure greater than atmospheric
pressure includes crystalline particles less than about 10 nm in
diameter. The crystalline particles can include a hybrid metal
oxide, a transition metal oxide, or any combination thereof. The
first mixture can be in the form of a colloidal suspension. In some
cases, an aqueous solution including a peroxide is combined with a
colloidal suspension including an amorphous metal hydroxide and a
silicon hydroxide in an aqueous carrier to form a colloidal
suspension including the transition metal peroxide and the silicon
peroxide. In some embodiments, a silicon chloride, a transition
metal chloride, and an acid are combined with an aqueous carrier to
form a mixture. The mixture can be neutralized and filtered to form
an amorphous metal hydroxide and a silicon hydroxide. The amorphous
metal hydroxide and a silicon hydroxide can be suspended in an
aqueous carrier to form a colloidal suspension including amorphous
metal hydroxide and silicon hydroxide.
[0014] In some implementations, preparing the composition includes
providing a mixture including a silicon peroxide, a transition
metal peroxide, and an aqueous carrier. The mixture can be boiled,
at a pressure greater than atmospheric pressure to form a
composition including the aqueous carrier and the condensation
product of the silicon peroxide and the transition metal peroxide.
In certain implementations, the composition includes crystalline
nano-sized particles including a transition, metal oxide.
[0015] In one aspect, a composition includes an aqueous carrier and
the condensation product of an organofunctional silane and a
transition metal peroxide. In certain implementations, the
composition includes crystalline nano-sized particles. The
nano-sized particles include a transition metal oxide. At least
some of the nano-sized particles are less than about 10 nm in
diameter. In some embodiments, the transition metal of the
transition metal peroxide is the same as the transition metal of
the transition metal oxide. The transition metal can be selected
from the group consisting of titanium, zinc, and combinations
thereof.
[0016] In some implementations, the composition includes an
additive selected from the group consisting of an organometallic
compound, a wetting agent, an organic compound, a metal, and
combinations thereof. In some cases, the composition includes a
filler. The filler can be substantially inert. The filler can
include, for example, carbon nanotubes. The weight of the filler
can be greater than the weight of the transition metal in the
composition.
[0017] In another aspect, a process for preparing a composition
includes providing a first mixture, and boiling the first mixture
at a pressure greater than atmospheric pressure to form a
composition. The first mixture includes an organofunctional silane,
a transition metal peroxide, and an aqueous carrier. The
composition that is formed includes the aqueous carrier and the
condensation product of the organofunctional silane and the
transition metal peroxide.
[0018] In some implementations, the composition formed by boiling
the first mixture at a pressure greater than atmospheric pressure
further includes crystalline nano-sized particles. The nano-sized
particles include a transition metal oxide. At least some of the
nano-sized particles are less than about 10 nm in diameter. In some
cases, the first mixture includes at least one additive selected
from the group consisting of an organometallic compound, a wetting
agent, an organic compound, a metal, a metal salt, a filler, and
combinations thereof. The first mixture can be in the form of a
colloidal suspension.
[0019] In certain implementations, the process further includes
combining an aqueous solution including a peroxide with a colloidal
suspension including an amorphous metal hydroxide in an aqueous
carrier to form a colloidal suspension. The colloidal suspension
includes the transition metal peroxide. The process can also
include combining a transition metal salt and an acid with an
aqueous carrier to form a second mixture, substantially
neutralizing the second mixture, filtering the second mixture to
form an amorphous metal hydroxide, and suspending the amorphous
metal hydroxide in an aqueous carrier to form the colloidal
suspension.
[0020] In another aspect, a process for preparing an article
includes providing a composition including an aqueous carrier and
the condensation product of an organofunctional silane and a
transition metal peroxide, applying the composition to a surface of
a substrate, and removing the aqueous carrier to form an article
with a coating on the surface of the substrate. In some
embodiments, the coating is removed from the substrate to form
nano-sized particles in powder form.
[0021] In some implementations, the composition includes
crystalline nano-sized particles. The nano-sized particles include
a transition metal oxide. A thickness of the coating can be less
than about 10 nm. The coating is covalently bonded to the surface
of the substrate. In some embodiments the substrate is porous. In
certain embodiments, the substrate is particulate. In one aspect, a
hybrid film-forming composition is prepared by forming an aqueous
mixture including an organofunctional silane, a metal chloride, and
an acid. A base is added to the aqueous mixture to substantially
neutralize the mixture and to form a hydroxide of the metal. A
colloidal suspension including the metal hydroxide and a siloxy
compound is formed. A peroxide-based solution is added to the
suspension to form a suspension including a peroxide of the metal.
The suspension is allowed to equilibrate at room temperature. The
suspension is boiled at a pressure greater than atmospheric
pressure to form a hybrid film-forming composition including the
condensation product of a siloxy compound and a metal peroxide. In
some implementations, the aqueous mixture is heated or boiled
before the base is added to the mixture.
[0022] In some implementations, a pH of the aqueous mixture before
neutralization may be less than 1. The metal chloride may include a
chloride of silicon, titanium, zirconium, tin, vanadium, gallium,
germanium, tellurium, hafnium, rhenium, iridium, platinum, or any
combination of two or more chlorides of silicon, titanium,
zirconium, tin, vanadium, gallium, germanium, tellurium, hafnium,
rhenium, iridium, or platinum. The metal chloride may be a
tetrachloride. The organofunctional silane may be, for example,
bis(triethoxysilyl)methane,
1,1,3,3-tetramethyl-1,3-diethoxydisiloxane, octochloro-trisiloxane,
tetraethoxysilane, or any combination thereof.
[0023] In another aspect, preparing an article includes providing a
composition including an aqueous carrier and the condensation
product of a siloxy compound and a metal peroxide. The composition
is applied to a surface of a substrate, and the aqueous carrier is
removed to form an article with a siloxy-peroxy hybrid metal
coating on the surface of the substrate.
[0024] In certain implementations, the composition includes
crystalline particles less than about 10 nm in diameter. The
particles can include a hybrid metal oxide, a transition metal
oxide, or a combination thereof. The composition can include
silicon oxide and transition metal oxide. A weight percentage of
the silicon oxide, based on total metal oxide, can be at least
about 50 wt %, at least about 95 wt %, or at least about 99 wt %. A
weight percentage of the transition metal oxide, based on total
metal oxide, can be at least about 95 wt %. In some cases, the
condensation product includes silicon, titanium, zirconium, or any
combination thereof.
[0025] In some implementations, the composition formed by boiling
the first mixture at a pressure greater than atmospheric pressure
includes crystalline particles less than about 10 nm in diameter.
The crystalline particles can include a hybrid metal oxide, a
transition metal oxide, or any combination thereof. The first
mixture can be in the form of a colloidal suspension. In some
cases, an aqueous solution including a peroxide is combined with a
colloidal suspension including an amorphous metal hydroxide and a
silicon hydroxide in an aqueous carrier to form a colloidal
suspension including the transition metal peroxide and the silicon
peroxide. In some embodiments, a silicon chloride, a transition
metal chloride, and an acid are combined with an aqueous carrier to
form a mixture. The mixture can be neutralized and filtered to form
an amorphous metal hydroxide and a silicon hydroxide. The amorphous
metal hydroxide and a silicon hydroxide can be suspended in an
aqueous carrier to form a colloidal suspension including amorphous
metal hydroxide and silicon hydroxide.
[0026] In some implementations, preparing the composition includes
providing a mixture including a silicon peroxide, a transition
metal peroxide, and an aqueous carrier. The mixture can be boiled
at a pressure greater than atmospheric pressure to form a
composition including the aqueous carrier and the condensation
product of the silicon peroxide and the transition metal peroxide.
In certain implementations, the composition includes crystalline
nano-sized particles including a transition metal oxide.
[0027] In one aspect, a composition includes an aqueous carrier and
the condensation product of an organofunctional silane and a
transition metal peroxide. In certain implementations, the
composition includes crystalline nano-sized particles. The
nano-sized particles include a transition metal oxide. At least
some of the nano-sized particles are less than about 10 nm in
diameter. In some embodiments, the transition metal of the
transition metal peroxide is the same as the transition metal of
the transition metal oxide. The transition metal can be selected
from the group consisting of titanium, zinc, and combinations
thereof.
[0028] In some implementations, the composition includes an
additive selected from the group consisting of an organometallic
compound, a wetting agent, an organic compound, a metal, and
combinations thereof. In some cases, the composition includes a
filler. The filler can be substantially inert. The filler can
include, for example, carbon nanotubes. The weight of the filler
can be greater than the weight of the transition metal in the
composition.
[0029] In another aspect, a process for preparing a composition
includes providing a first mixture, and boiling the first mixture
at a pressure greater than atmospheric pressure to form a
composition. The first mixture includes an organofunctional silane,
a transition metal peroxide, and an aqueous carrier. The
composition that is formed includes the aqueous carrier and the
condensation product of the organofunctional silane and the
transition metal peroxide.
[0030] In some implementations, the composition formed by boiling
the first mixture at a pressure greater than atmospheric pressure
further includes crystalline nano-sized particles. The nano-sized
particles include a transition metal oxide. At least some of the
nano-sized particles are less than about 10 nm in diameter. In some
cases, the first mixture includes at least one additive selected
from the group consisting of an organometallic compound, a wetting
agent, an organic compound, a metal, a metal salt, a filler, and
combinations thereof. The first mixture can be in the form of a
colloidal suspension.
[0031] In certain implementations, the process further includes
combining an aqueous solution including a peroxide with a colloidal
suspension including an amorphous metal hydroxide in an aqueous
carrier to form a colloidal suspension. The colloidal suspension
includes the transition metal peroxide. The process can also
include combining a transition metal salt and an acid with an
aqueous carrier to form a second mixture, substantially
neutralizing the second mixture, filtering the second mixture to
form an amorphous metal hydroxide, and suspending the amorphous
metal hydroxide in an aqueous carrier to form the colloidal
suspension.
[0032] In another aspect, a process for preparing an article
includes providing a composition including an aqueous carrier and
the condensation product of an organofunctional silane and a
transition metal peroxide, applying the composition to a surface of
a substrate, and removing the aqueous carrier to form an article
with a coating on the surface of the substrate. In some
embodiments, the coating is removed from the substrate to form
nano-sized particles in powder form.
[0033] In some implementations, the composition includes
crystalline nano-sized particles. The nano-sized particles include
a transition metal oxide. A thickness of the coating can be less
than about 1 nm. The coating may be hydrophilic or hydrophobic. The
contact angle of water on the hydrophilic coating may be less than
about 20.degree., less than about 10.degree., or less than about
5.degree.. The coating is covalently bonded to the surface of the
substrate. In some embodiments, the substrate is porous. In certain
embodiments, the substrate is particulate.
[0034] Implementations can include compositions and articles
prepared according to the above-described processes, as well as any
combination of the above features.
[0035] Other features will be apparent from the description, the
drawings, and the claims.
DESCRIPTION OF DRAWINGS
[0036] FIG. 1 is a flow chart of a procedure for forming aqueous
polymeric molecular hybrid nanocrystals.
[0037] FIG. 2 depicts a hydrolysis reaction of a metal
alkoxide.
[0038] FIG. 3 depicts condensation of peroxy metal hydroxy silanes
to form a crosslinked oligomer.
[0039] FIG. 4 depicts a first coating and a second coating on a
substrate.
[0040] FIG. 5 depicts a first coating and a second coating on a
particle.
[0041] FIG. 6 depicts a model of a silicon peroxide in
solution.
[0042] FIG. 7 depicts a model of sub-mesoporous metal peroxide
interactions in solution.
[0043] FIG. 8 is graph showing stain remediation provided by a
hybrid metal oxide coating.
[0044] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0045] A solution or aqueous dispersion of polymeric molecular
hybrid nanocrystals can be prepared following a sequence of steps
combining selected reactants and additives under certain reaction
conditions. Compositions including a solution or aqueous dispersion
of polymeric molecular hybrid nanocrystals can be applied to macro
or micro surfaces (such as microparticle powders) to form a
protective and/or functional coating with metal oxides, metals, and
other optional components. The coatings can include nanofilms and
composite films formed from vehicle systems having nanohybrid
crystals that can also be used as an inorganic vehicle system for
dispersion of nanoparticles. The compositions can be used to
prepare nanopowders and nanocomposite powders, as well as vaporized
nanoparticles, in addition to coatings.
[0046] As used herein, "substrate" generally refers to a solid
object of any size. For instance, a substrate can be a window, a
microchip, or a plurality of particles, such as nanoparticles or
micron-sized particles. In some cases, compositions described
herein are mixed with a substrate rather than, or in addition to,
applying the composition to a surface of the substrate to alter
bulk properties of the substrate. Mixing a composition with a
substrate includes dispersing the composition in the substrate such
that the composition is distributed substantially homogeneously
throughout the substrate. For example, if the substrate is cement,
a composition or components of a composition can be mixed into dry
cement or into prepared (wet) cement. As another example, a
composition can be mixed into a molten material that will form a
glass prior to cooling so that components of the composition are
dispersed within the glass.
[0047] Polymeric molecular hybrid nanocrystal (PMHNC) compositions
can include additives such as transition metal salts,
organofunctional silanes, organometallic compounds, wetting agents
(including non-reactive silanes), other reactive and/or
non-reactive (or substantially inert) organic and/or inorganic
compounds, and any combination thereof. These aqueous compositions
include at least about 90%, at least about 95%, or at least about
98% water. Temperature, pressure, and pH of the aqueous reaction
mixture are selectively controlled throughout the preparation of a
PMHNC composition.
[0048] Components of the aqueous inorganic PMHNCs described herein
can be chosen to form coatings that have catalytic, photocatalytic,
anti-microbial, anti-viral, anti-fungal, anti-corrosive,
anti-fouling, semi-conductive, conductive, insulative,
electromagnetic, transparent, optical, emissive, flame retardant,
piezoelectric, and other selected properties. Coatings formed from
the compositions; described herein can be instrumental in air/water
remediation, bio-medical applications, thermoset-thermoplastic
reinforcement, pigment dispersion, hydrogen storage, dye sensitized
solar cells, and super capacitor thin films, with uses in
electrical applications, surface studies optics, increased
refractive index coatings, electro-optics, acousto-optics, laser
optics, etc.
[0049] Referring to FIG. 1, a procedure 100 depicts preparation of
an aqueous PMHNC composition. Initially, an amorphous metal
hydroxide mixture is prepared. In step 102, an acidic aqueous
mixture of one or more metal salts (including, for example, metal
M.sup.1) is formed. The metal salts can be transition metal
chloride or halide salts of one or more metals such as silicon,
titanium, vanadium, gallium, germanium, zirconium, tin, tellurium,
hafnium, rhenium, iridium, and platinum. In some embodiments, the
metal salts are metal tetrachlorides.
[0050] A pH of the mixture is less than about 1. Acids used to
acidify the mixture may be strong acids such as, for example,
hydrochloric acid, hydrofluoric acid, nitric acid, and sulfuric
acid, or any combination thereof. Other acids that may be used
include, but are not limited to, acetic acid, arginine, azelaic
acid, behenic acid, benzenesulfonic acid, boric acid, butyric acid,
capric acid, castor oil acid, chromic acid, docosanic acid,
dodecylbenesulfonic acid, fluohydric acid, fluosilicaten, formic
acid, fumaric acid, glutamine, glycine, hydrocyanic acid,
hydroxyproline, hydroxystearic acid, isophthalic acid, lauric acid,
linoleic acid, lysine, malonic acid, metat-phthalic acid,
methionine, myristic acid, oleic acid, ortho-phthalic acid,
orthophosphoric acid, oxalic acid, palmitic acid, para-phthalic
acid, para-toluenesulfonic acid, phenylanaline, phosphoric acid,
phosphorus acid, phthalic acid, pimelic acid, polyphosphoric acid,
propionic acid, ricinoleic acid, sodium formate, stearic acid,
succinic acid, sulfanilic acid, sulfamic acid, tartaric acid,
terephthalic acid, toluenesulfonic acid, and other amino acids,
carboxylic acids, carboxylic chlorides, chloride acids,
dicarboxylic acids, fatty acids, halide acids, organic acids,
organic diacids, polycarboxylic acids, and any combination
thereof.
[0051] Step 104 includes the optional addition of one or more
additional metal salts (including, for example, metal M.sup.2,
which can be a transition metal), organometallic compounds
(including, for example, M.sup.3, which can be a transition metal),
an organofunctional silane, or combinations thereof, to the mixture
formed in step 102. Any of M.sup.1, M.sup.2, and M.sup.3 can be the
same or different.
[0052] The metal salts are chosen to impart desirable properties to
the PMHNC composition. For example, a zinc salt such as ZnCl.sub.2
can be added to impart anti-corrosion properties. In some cases,
metals are chosen for a desired solubility at a given pH in the
process depicted in FIG. 1. Alternatively, the pH of a composition
in the process can be adjusted to achieve a desired solubility of a
selected metal salt.
[0053] In some embodiments, the second metal salt is a metal
chloride. The metal chloride can be a tetrachloride salt such as,
for example, SiCl.sub.4, TiCl.sub.4, GeCl.sub.4, VCl.sub.4,
GaCl.sub.4, ZrCl.sub.4, SnCl.sub.4, TeCl.sub.4, HfCl.sub.4,
ReCl.sub.4, IrCl.sub.4, PtCl.sub.4, or other chloride salts such
as, for example, Na.sub.2PtCl.sub.6, CCl.sub.3CO.sub.2Na,
Na.sub.2PdCl.sub.4, NaAuCl.sub.4, NaAlC.sub.4, ClNaO.sub.3,
MgCl.sub.2, AlCl.sub.3, POCl.sub.3, PCl.sub.5, PCCl.sub.3, KCl,
MgKCl.sub.3, LiCl.KCl, CaCl.sub.2, FeCl.sub.2 MnCl.sub.2,
Co(ClO.sub.4).sub.2, NiCl.sub.2, Cl.sub.2Cu, ZnCl.sub.2,
GaCl.sub.3, SrCl.sub.2, YCl.sub.3, MoCl.sub.3, MoCl.sub.5,
RuCl.sub.3, RhCl.sub.3, PdCl.sub.2, AsCl.sub.3, AgClO.sub.4,
CdCl.sub.2, SbCl.sub.5, SbCl.sub.3, BaCl.sub.2, CsCl, LaCl.sub.3,
CeCl.sub.3, PrCl.sub.3, SmCl.sub.3, GdCl.sub.3, TbCl.sub.3,
HoCl.sub.3, ErCl.sub.3, TmCl.sub.3, YbCl.sub.3, LuCl.sub.3,
WCl.sub.6, ReCl.sub.5, ReCl.sub.3, OsCl.sub.3, IrCl.sub.3,
PtCl.sub.2, AuCl, AuCl.sub.3, Hg.sub.2Cl.sub.2, HgCl.sub.2,
HgClO.sub.4, Hg(ClO.sub.4).sub.2, TICl.sub.3, PbCl.sub.2,
BiCl.sub.3, GeCl.sub.3, HfCl.sub.2O, Al.sub.2Cl.sub.6, BiOCl,
[Cr(H.sub.2O).sub.4Cl.sub.2]Cl.sub.2.2H.sub.2O, CoCl.sub.2,
DyCl.sub.3.6H.sub.2O, EuCl.sub.2, EuCl.sub.3.6H.sub.2O,
NH.sub.4AuCl.sub.4.xH.sub.2O, HAuCl.sub.4.xH.sub.2O, KAuCl.sub.4,
NaAuCl.sub.4.xH.sub.2O, InCl.sub.3, (NH.sub.4).sub.3IrCl.sub.6,
K.sub.2IrCl.sub.6, MgCl.sub.2.6H.sub.2O, NdCl.sub.3,
(NH.sub.4).sub.2OsCl.sub.6, (NH.sub.4).sub.2PdCl.sub.6,
Pd(NH.sub.3).sub.2Cl.sub.2, [Pd(NH.sub.3)].sub.4Cl.sub.2.H.sub.2O,
(NH.sub.4).sub.2PtCl.sub.6, Pt(NH.sub.3).sub.2Cl.sub.2,
Pt(NH.sub.3).sub.2Cl.sub.2, [Pt(NH.sub.3).sub.4]Cl.sub.2.xH.sub.2O,
[Pt(NH.sub.3).sub.4][PtCl.sub.4], K.sub.2PtCl.sub.4, KClO.sub.4,
K.sub.2ReCl.sub.6, (NH.sub.4).sub.3RhCl.sub.6,
[RhCl(CO)((C.sub.6H.sub.5).sub.3P).sub.2],
[RhCl(C.sub.6H.sub.5)3P).sub.3], [Rh(NH.sub.3).sub.5Cl]Cl.sub.2,
K.sub.3RhCl.sub.6, RbCl, RbClO.sub.4, (NH.sub.4).sub.2RuCl.sub.6,
[RuCl.sub.2((C.sub.6H.sub.5).sub.3P).sub.3],
{Ru(NH.sub.3).sub.6}Cl.sub.2, K.sub.2RuCl.sub.6,
ScCl.sub.3.xH.sub.2O, AgCl, NaCl, TlCl, SnCl.sub.2, and additional
water adducts thereof.
[0054] In some cases, PMHNC compositions are used to chemically
bind other organometallic compounds (for example, in a
monomeric/oligomeric/polymeric network or matrix), providing an
inorganic vehicle system that allows inclusion of organometallic
compounds. Desired properties of a film or coating are enhanced by
adding selected organometallic compounds to impart or enhance
properties such as mechanical strength, electrical conductivity,
corrosion resistance, anti-fouling characteristics, etc.
[0055] Organometallic compounds added in optional step 104 can be
chosen such that one or more organic substituents undergo
hydrolytic cleavage in the acidic mixture in step 102, as shown in
FIG. 2. Organometallic compounds added in optional step 104 can
include, for instance, metal alkoxides such as methoxides,
ethoxides, methoxyethoxides, butoxides, isopropoxides, pentoxides,
etc., as well as pentadionates, proprionates, acetates, hydroxides,
hydrates, stearates, oxalates, sulfates, carbonates, and/or
acetylacetonates, etc., of metals such as zinc, tungsten, titanium,
tantalum, tin, molybdenum, magnesium, lithium, lanthanum, indium,
hafnium, gallium, iron, copper, boron, bismuth, antimony, barium,
zirconium, zinc, yttrium, vanadium, tin, silver, platinum,
palladium, samarium, praseodymium, nickel, neodymium, manganese,
magnesium, lithium, lanthanum, indium, holmium, hafnium, gallium,
gadolinium, iron, europium, erbium, dysprosium, copper, cobalt,
chromium, cesium, cerium, aluminum, barium, beryllium, cadmium,
calcium, iridium, arsenic, germanium, gold, lutetium, niobium,
potassium, rhenium, rhodium, rubidium, ruthenium, scandium,
selenium, silicon, strontium, tellurium, terbium, thulium, thorium,
ytterbium, and yttrium.
[0056] Organofunctional silanes added in step 104 promote adhesion
between organic polymers and inorganic substrates and act as
crosslinkers and hardeners for binder systems. Bonding strength and
hardness (or abrasion resistance) of a film or coating formed on a
substrate are increased by the addition of organofunctional silanes
in step 104 during preparation of a composition to form peroxy
metal hydroxy si lane (PMHS) monomers, which polymerize to form an
inorganic polymeric PMHNC composition. As used herein, "PMHS
monomers" generally refers to monomers including a metal peroxide
species covalently bonded to a metal silanol species to form a
structure such as a silicate matrix
(--Si(OH).sub.y--O-M.sup.1(OOH).sub.x--O--Si(OH).sub.y--). As used
herein, "organofunctional silane" generally refers to a
silicon-containing compound with one or more hydrolyzable
substituents. Organofunctional silanes are typically bifunctional
molecules, depicted in some cases as Y--Si(OR).sub.3, with
hydrolyzable alkoxy groups R. In the presence of water, the alkoxy
groups R hydrolyze to form reactive silanol (Si--OH) groups, as
shown in FIG. 2, with the loss of alcohol (R--OH). The choice of
alkoxy groups affects the rate and extent of the hydrolysis
reaction.
[0057] The reaction of the silanol groups and the nature of Y
determine how the silane functions in a composition. Y can be
organic or inorganic, hydrophobic or hydrophilic, ionic, cationic,
zwitterionic, or nonionic. In some cases, Y is halogenated (for
instance, chlorinated or fluorinated). Y can act as a surface
modifier in a coating of a substrate such as a particle (for
instance, a pigment), colloid (for instance, latex), etc.
[0058] If Y is a nonreactive group, such as an alkyl group, the
organofunctional silane is generally referred to as a nonreactive
silane. If Y is a reactive organic group, such as an alkoxy group,
the organofunctional silane is generally referred to as a reactive
silane. In some cases, Y is a reactive organic group that binds to
reactive groups of a polymer, and the organofunctional silane
behaves as a co-monomer in a polymerization reaction.
[0059] Organofunctional silanes suitable for PMHNC compositions
resulting in the formation of inorganic polymeric vehicle systems
include, but are not limited to, alkoxysilanes such as
tetramethoxysilane and tetraethoxysilane, dipodal silanes such as
bis(trimethoxysilylpropyl)-amine, bis(triethoxysilyl)methane,
silsesquioxanes, siloxane, disiloxane, polydimethylsiloxanes,
disilylmethylene, disilylethylene, silphenylene, metal silanolates,
silazanes, (RO).sub.3Si--CH.sub.2CH.sub.2CH.sub.2X where X is --Cl,
C.ident.N, --NH.sub.2, --SH, hybrid acetate-alkene, epoxide, or any
combination thereof. Other suitable silanes can have particular
functionality, including substituents such as allyl, alkynyl,
phenyl, hydroxyl, phenoxy, and acetoxy groups, cyclic trimers,
tetramers and pentamers, halogens, ketones, azides, and
isocyanates. Some organofunctional silanes, such as
amino-functional silanes, are self-catalyzing, while other
organofunctional silanes require a small amount of acid to initiate
hydrolysis. An organofunctional silane can be chosen based on
properties such as desirable reaction kinetics. For example,
methoxysilanes are known to hydrolyze more quickly than
ethoxysilanes.
[0060] Bis(trimethoxysilylpropyl)amine, shown below, is an example
of an organofunctional silane (amine difunctional dipodal silane)
with non-polar alkyl segments. Condensation of
bis(trimethoxysilylpropyl)amine with the polar metal hydroxide
colloidal suspension in step 110 yields a film-forming molecular
hybrid inorganic vehicle system with non-polar, segments, capable
of improving, dispersion of additives, such as pigments, in an
aqueous composition.
##STR00001##
[0061] 1,2-bis(trimethoxysilyl)decane, shown below, is another
example of a reactive organofunctional silane with a non-polar
segment. Condensation of 1,2-bis(trimethoxysilyl)-decane with the
polar metal hydroxide colloidal suspension in step 110 component
also yields a film-forming molecular hybrid inorganic vehicle
system with non-polar segments, capable of improving dispersion of
additives, such as pigments, in an aqueous composition.
##STR00002##
[0062] In some implementations, nonreactive organofunctional
silanes that impart dispersibility in a variety of resins, and
solvents are used to provide steric stabilization and wetting
properties to PMHNC compositions. Polar, non-ionic water-soluble
wetting agents (neutral pH) with a chemically bonded ethylene
glycol functionality are particularly suitable. These ethylene
glycol functional silanes allow tailoring of surface energy to
substrate surfaces within a wide pH range. Since these ethylene
glycol functional silanes are hydrophilic but nonreactive, their
addition promotes even application of compositions as well as
substantially homogeneous dispersion of particles, such as
nanoparticle composites, in aqueous compositions. The hydrophilic
surface of most mineral fillers and pigments can be, made
hydrophobic to be more compatible with hydrophobic organic resins.
The hydrophobation that occurs when the PMHNC composite alkylsilane
binds to the filler particle surfaces allows for improved
dispersion of the filler particles into the resin, as well as
improved mechanical strength of the composition. Ethylene glycol
functional silanes and/or other nonreactive organofunctional
silanes can be added under boiling and/or pressure greater than
atmospheric pressure to a PMHNC composition, along with an
organofunctional silane, to improve particle dispersibility and
enhance mechanical performance of a composition.
[0063] Organofunctional silanes are effective adhesion promoters
when the substrate possesses chemically active sites on the
surface, such as hydroxyl or oxide groups. PMHNC vehicle systems
can be formulated to further enhance adhesion to substrates
(including particulate substrates) with chemically active sites
including, but not limited to, glasses, metals, and metal
alloys.
[0064] Metal substrates can include aluminum, antimony, arsenic,
beryllium, bismuth, cadmium, calcium, cerium, chromium, cobalt,
copper, dysprosium, erbium, europium, gallium, gadolinium,
germanium, gold, holmium, indium, iridium, iron, lanthanum,
lithium, lutetium, magnesium, manganese, molybdenum, neodymium,
nickel, niobium, palladium, platinum, praseodymium, rhenium,
rhodium, ruthenium, samarium, scandium, selenium, silicon,
tantalum, tellurium, terbium, thorium, thulium, tin, titanium,
tungsten, ytterbium, yttrium, and zinc.
[0065] Metal alloy substrates can include any combination of
metals, including scandium-aluminum, yttrium-aluminum,
beryllium-copper, calcium-magnesium, calcium-aluminum,
calcium-silicon, chromium-silicon, samarium-cobalt,
scandium-aluminum, titanium-nickel, alloys of aluminum (including
one or more of lithium, copper, silicon, magnesium, palladium,
manganese, etc.), alloys of bismuth (including one or more of lead,
tin, cadmium, etc.), alloys of cobalt (including one or more of
chromium, tungsten, carbon, etc.), alloys of copper (including one
or more of beryllium, silver, zinc, tin, aluminum, nickel, gold,
silver, iron, zinc, tin, manganese, lead, etc.), alloys of gold
(including one or more of copper, silver, etc.), alloys of gallium
including gallinstan, alloys of indium (including one or more of
bismuth, tin, etc.), alloys of iron (such as steel, carbon steel,
stainless steel, surgical stainless steel, and/or including one or
more of carbon, chromium, nickel, molybdenum, silicon, tungsten,
manganese, cobalt, nickel, cobalt, ferroboron, ferrochrome,
ferromanganese, ferromolybdenum, ferronickel, ferrophosphorus,
ferrotitanium, ferrovanadium, ferrosilicon, ferrotungsten, etc.),
alloys including lead, copper, tin, and (optionally) antimony,
alloys including magnesium, aluminum, and (optionally) zinc, alloys
of mercury-amalgam, alloys, of nickel (including one or more of
copper, zinc; chromium, molybdenum, iron, nickel, manganese,
silicon, magnesium, silicon, bronze, copper, etc.), titanium-shape
memory alloy, alloys of silver (including one or more of copper,
gold, etc.), alloys of fin (including one or more of copper,
antimony, lead, etc.), alloys of zirconium such as zircaloy, and
alloys of uranium or depleted uranium with other metals such as
titanium or molybdenum.
[0066] Polymeric substrates can include thermoplastics such as
acrylonitrile-butadiene-styrene (ABS), acetals or polyoxymethylenes
(POM, DELRIN.RTM.), acrylate-styrene-acrylonitrile (ASA),
cellulosic polymer, cyclic olefin copolymer (COC), acrylics,
(poly)acrylics, polymethyl-methacrylate (PMMA), polylactic acid
(PLA), butyls or polyisobutylenes (polybutenes), ethylene
copolymers (polyethylene acrylate acid (EAA), polyethylene methyl
acrylate (EMAC), polyethylene ethyl acrylate (EEA), polyethylene
vinyl acetate (EVA), polyethylene butyl acrylate (EBAC),
polyethylene vinyl acetate (EVA or EVAC), polyethylene vinyl
alcohol (EVAL or EVOH), polyethylene propylene terpolymer (EPM),
polyethylene (PE, functionalized PE, high density PE (HDPE), low
density PE (LDPE), linear low density PE (LLDPE), medium density
(MDPE), fluoropolymers such as polytetrafluoroethylenes (PTFE) or
polyvinylidene fluorides (PVDF), ionomers, liquid crystal polymers
(LCP), ketones, polyaryletherketones, or polyetheretherketones
(PEEK), polyketone, polyurethane (PUR), polyether sulfone (PES),
polyethylenes, polyamides (PA, PAII, P112, PA4,6, PA6, PA6,6,
PA6-10, semi-aromatic-PA), polyamidimide (PAI), polycarbonates,
thermoplastic polyesters or terphthalates (PET, PBT, PETG),
polyethylenes (PEN, PTT), thermoplastic elastomers (TPE, TPE-E,
TPE-S), methacrylated butadiene styrene copolymer (MBS), polyether
block amides (PEBA), copolyester elastomers (COPE), thermoplastic
olefins (TPE-O) styrene-butadiene-styrene (SBS),
styrene-ethylene-butadiene-styrene (SEBS), thermoplastic urethane
(TPE-U), thermoplastic vulcanite (TPV), polyetherimides (PEI),
polyimides, polyolefins, polyphenylene oxides (PPO), polyphenylene
sulfides (PPS), polypropylenes (PP), polysulphones,
polyphthalamides (aramids), polyvinylidene chloride (PVDC), styrene
or polystyrene, expanded polystyrene (EPS), general purpose crystal
(GPPS), high impact polystyrene (HIPS), styrene acrylonitrile
copolymers (SAN, ASA, AES), styrene butadiene rubber (SBR), styrene
maleic anhydride (SMA), vinyl or polyvinyl chlorides (PVC),
polysulfone (PSU), polylactides (PLA), and ethylene-vinyl
acetates.
[0067] Other substrates include thermoset resins such as diallyl
phthalate (DAP), epoxy, fluoropolymers, furan, melamine, phenolic,
polybutadiene, polyester, alkyd, vinyl ester, polyamide, polyurea,
polyisocyanate, polyurethane, silicone, thermoset elastomers
(isoprene), resorcinol or resorcin, vulcanized fiber, and specialty
resins, such as thermosets, epoxy resin (EP), melamine formaldehyde
resin (MF), phenolic/phenol formaldehyde resin (P/PF), urea
formaldehyde resin (UF), unsaturated polyester (UPR), and (UV)
curable (meth-)acrylate.
[0068] Still other substrates include textiles, building materials
such as concrete, ceramics, pigments (organic and inorganic),
fillers, fiber materials, electronics, carbon, graphite, inorganic
materials, organic materials, wood, paper, waste, skin, hair, and
in particular, substrates and surfaces such as surgical steel,
stainless steel, untreated steel, medical devices, fiberglass,
cement, and fiber optics.
[0069] Addition of organofunctional silanes in step 104, before
neutralization in step 106, allows incorporation of siloxy groups
at a molecular level into the vehicle system, resulting in a
siloxy-peroxy hybrid (mixed metal oxide) film former. "Siloxy" is
used herein to refer to any compound including --Si--R--, where R
is an aliphatic or aromatic group that may include heteroatoms such
as oxygen, nitrogen, sulfur, etc. In some cases, the acid sol
formed in steps 102 and 104 is heated or boiled (e.g., refluxed) in
step 105 prior to neutralization in step 106. The pH of the mixture
is less than 1, or substantially less than 1. This additional
heating step increases the solubility of components in the mixture
(e.g., organometallics, metal chlorides, silanes), yielding a more
homogeneous solution with smaller particles, thus promoting more
effective and homogeneous neutralization. The resulting hybrid
siloxy-peroxy hybrid metal oxide film, formers and PMHNCs
demonstrate desirable properties such as, for example, increased
photocatalytic efficacy, enhanced hydrophobic characteristics, more
robust anti-corrosion capabilities etc.
[0070] In step 106 of FIG. 1, a strong base, such as NH.sub.4OH or
NaOH, is added to the mixture to form a metal hydroxide colloidal
suspension. The base substantially neutralizes the aqueous mixture.
Slow addition of the base and agitation of the mixture allow
components of the mixture to remain suspended during, as well as
after, the neutralization process. The pH after neutralization may
be at least 7, or at least 8. The supernatant can be discarded.
[0071] In step 108, the amorphous metal hydroxide mixture is washed
(for example, by various forms of decantation or filtration) to
remove ions, such as chloride and other ions, from the mixture.
Washing can include adding distilled or deionized water (DIW) to
the mixture, agitating the mixture, allowing the mixture to stand,
and decanting. Washing is repeated until ions are substantially
undetectable in the supernatant. Testing for chloride ions may be
achieved, for example, by using silver nitrate to measure levels of
chloride ions in the supernatant or by using a chloride ion probe.
In some implementations, washing can be repeated until the
concentration of unwanted ions in the supernatant is less than
about 50 parts per million (ppm). In some cases, the mixture can be
subjected to centrifugal dehydration. After sufficient removal of
ions, an amorphous metal hydroxide can be collected through
filtration or other suitable means. The final supernatant is
slightly to moderately basic (for example, having a pH of about
8-10).
[0072] In step 110, the amorphous metal hydroxide is dispersed in
water to form a colloidal suspension. The water can be deionized or
distilled. The amorphous metal hydroxide colloidal suspension can
be slightly basic to moderately basic (for example, having a pH of
about 8-10). In step 110, or in one or more later steps, water
added is added in an amount needed to form a composition of a
desired density. The density of the composition can be adjusted
depending on the surface or substrate to which the solution is to
be applied. For example, for porous or absorbent surfaces or
substrates such as concrete, the density of the mixture can be
relatively high, and for non-porous or non-absorbent surfaces or
substrates such as glass, the density of the mixture can be
relatively low. The thickness of the applied film increases with
the density of the mixture.
[0073] In optional step 112, one or more organofunctional silanes,
organometallics, wetting agents, and/or other reactive or inert
components can be added to the aqueous metal hydroxide colloidal
suspension. Suitable organofunctional silanes, and organometallics
were described above as optional additions in step 104.
[0074] One or more wetting agents can be added in optional step 112
to improve hydrophobicity or wettability of the composition on some
substrates, such that a thinner film of the composition can be
applied to a substrate. Thinner films have advantageously reduced
yellow appearance, reduced moire patterns, and reduced cure times.
Suitable wetting agents include, but are not limited to,
polyethylene oxide silane, isopropyl alcohol, polar (hydrophilic)
nonionic ethylene glycol functional silanes, non-polar
(hydrophobic) PMHNC compositions created from condensation of
1,2-bis(trimethoxysilyl)decane with polar metal hydroxide as
described above, etc.
[0075] The amount of wetting agent added to the mixture can be
adjusted depending on other additives in the composition, the type
of substrate or surface to which the composition will be applied,
etc. In some embodiments, compositions intended for highly water
absorbent substrates or surfaces, such as concrete, do not require
the addition of a wetting agent. In other embodiments, as much as
0.03 vol % of a wetting agent can be added to a composition
intended for low surface tension or highly water repellant
substrates or surfaces, such as glass, polished metals, or certain
silicon wafers.
[0076] Other components that can be added in optional step 112 to
impart selected physical and chemical characteristics to a
composition include reactive and/or inert (substantially
unreactive) organic and/or inorganic compounds. Inorganic compounds
added in optional step 112 can include, for example, metal oxides,
such as oxides of zirconium, zinc, yttrium, tungsten, titanium,
tellurium, tantalum, tin, silver, silicon, scandium, samarium,
praseodymium, niobium, nickel, neodymium, molybdenum, iron,
manganese, magnesium, lutetium, lithium, lanthanum, indium,
holmium, hafnium, germanium, gallium, gadolinium, europium,
terbium, dysprosium, copper, cobalt, chromium, cesium, cerium,
boron, aluminum, bismuth, antimony, ruthenium, beryllium, cadmium,
calcium, indium, etc., and titanates, such as titanates of
strontium, lead, barium, etc.
[0077] Organic compounds added in optional step 112 can include
monomers such as methylmethacrylate, pentaerythritol, TMP, TME,
diacids, carboxylic acids, olefins, dienes, acetylenes, styrenes,
acrylic acids, ring monomers (such as cyclic ethers, lactones,
lactams, cyclic amines, cyclic sulfides, cyclic carbonates, cyclic
acid anhydrides, cyclic iminoethers, amino acid N-carboxy
anhydrides, cyclic imides, phosphorus containing cyclic compounds,
silicon containing compounds, cyclic olefins), and any combination
thereof. As with the organometallic compounds, the additives can
bond with the PMHS species (monomers, oligomers, etc.) to form
oligomers dispersed in the composition. Composite PMHNC nanopowders
designed to exhibit partial non-reactive, non-polar functionality
and partial reactive silane and organometallic functionality can be
incorporated into hydrophobic monomers. As an example, condensation
of a reactive silane such as 1,2-bis(trimethoxysilyl)decane added
in step 124 can provide increasing non-polar functionality to the
PMHS species. Increasing the added amount of the
1,2-bis(trimethoxysilyl)decane to the PMHS will eventually exhaust
the metal peroxide, thus optimizing-hydrophobicity throughout the
PMHNC. The PMHNC nanocomposites can be dehydrated as described
herein and incorporated into the nonpolar monomers.
[0078] Other substantially nonreactive or inert additives added in
optional step 112 include, for example, fillers, pigments, metals,
carbon nanotubes (single-walled and/or multi-walled), nanographite
platelets, silica aerogels; carbon aerogels, glass flakes, quantum
dots, nanoparticles, etc. Nanoparticles can include, for example,
nanoparticles of aluminum, aluminum nitride, aluminum oxide,
antimony, antimony oxide, antimony tin oxide, barium titanate;
beryllium, bismuth oxide, boron carbide, boron nitride, calcium
carbonate, calcium chloride, calcium oxide, calcium phosphate,
cobalt, cobalt oxide, copper, dysprosium, dysprosium oxide, erbium,
erbium oxide, europium, europium oxide, gadolinium, gadolinium
oxide, gold, hafnium oxide, holmium, indium, indium oxide, iridium,
iron cobalt, iron, iron nickel, iron oxide, lanthanum, lanthanum
oxide, lead oxide, lithium manganese oxide, lithium, lithium
titanate, lithium vanadate, lutetium, magnesium, magnesium oxide,
molybdenum, molybdenum oxide, neodymium, neodymium oxide, nickel,
nickel oxide, nickel titanium, niobium, niobium oxide, palladium,
platinum, praseodymium, praseodymium oxide, rhenium, ruthenium,
samarium, samarium oxide, silicon carbide, silicon nanoparticles,
silicon nanotubes, silicon nitride, silicon oxide, silver,
strontium carbonate, strontium titanate, tantalum, tantalum oxide,
terbium, terbium oxide, thulium, tin, tin oxide, titanium carbide,
titanium, titanium nitride, titanium oxide, tungsten carbide,
tungsten, tungsten oxide, vanadium oxide, ytterbium, yttria
stabilized zirconia, yttrium, zinc oxide, zirconium, zirconium
oxide, and any combination thereof.
[0079] Other particles ranging in size from nanometers to microns,
such as polycrystalline, single crystal, or shaped charge
microparticles and/or nanoparticles can be added in optional step
112 or coated with PMHNC compositions. These particles include
antimony selenide, antimony telluride, bismuth selenide, bismuth
telluride, boron carbide, silicon carbide, tungsten carbide,
gallium antimonide, gallium arsenide, gallium indium antimonide,
gallium indium arsenide, gallium phosphide, gallium(II) telluride,
gallium(III) telluride, germanium telluride, indium antimonide,
indium arsenide, indium phosphides, indium phosphide arsenide,
indium selenide, indium sulfide, indium telluride, silicon
arsenide, silicon phosphides, tin arsenide, tin selenide, tin
telluride, zinc telluride, etc.
[0080] In some implementations, the amorphous metal hydroxide
colloidal suspension composition formed in step 110 is applied
directly to a surface to form a coating on the surface, as depicted
by step 114. In other implementations, the amorphous metal
hydroxide colloidal suspension composition formed in step 110 is
dehydrated (for instance, spray dried) and collected as a powder to
be used in nanopowder or nanocomposite powder form.
[0081] In step 116, a peroxide-based solution is added to the
amorphous metal hydroxide colloidal suspension, lowering a pH of
the composition to about 1 or below. The peroxide-based solution
can include, for example, hydrogen peroxide, benzoyl peroxide,
tert-butyl hydroperoxide, 3-chloroperoxybenzoic peroxide,
di-tert-butyl peroxide, dicumyl peroxide, methylethyl ketone
peroxide, [dioxybis(1-methylpropylidene)]bishydroperoxide,
(1-methylpropylidene)bishydroperoxide, peracetic acid, and
combinations thereof. The mixture is cooled and allowed to react
for a period of time to form a stabilized amorphous
(non-crystalline) metal peroxide colloidal suspension. The
stabilized amorphous metal peroxide colloidal suspension can
include metal peroxides such as M(OOH).sub.x, M(OOH).sub.yOM,
M(OOH).sub.yOM, M(OOH).sub.yOSi, etc., where M can be any
combination of M.sup.1, M.sup.2, or M.sup.3, and various
condensation products of these and other species, depending on the
components in the composition, where x and y are determined by the
oxidation state of M and the number of other substituents.
[0082] In some implementations, cooling is achieved in a sealed
reaction vessel by reducing the pressure in the vessel to less than
atmospheric pressure. The pressure in the vessel can be adjusted to
achieve a desired temperature. In some cases, the mixture is cooled
by a reduction in pressure of the system together with optional
external thermal cooling of the system. The formulation of the
mixture can determine the extent of vacuum needed to reduce the
temperature of the system by a desired amount, or to a desired
threshold.
[0083] The composition can be, agitated during cooling. The level
of agitation is chosen to achieve dissociation of ions, such that
an amorphous metal peroxide colloidal suspension is formed without
agglomeration of the particles. For example, the level of agitation
can be between about 500 and about 10,000 rotations per minute
(rpm) depending on the volume of the mixture. In some
implementations, the level of agitation is between about 2500 and
about 7000 rpm. If a wetting agent is added, for example, in step
112, the need for shaking or agitation is reduced or eliminated.
The presence of a wetting agent can reduce a thickness of the
coating or film and enhance film-forming characteristics.
[0084] When the reaction in step 116 is substantially complete, the
resulting amorphous metal peroxide colloidal suspension is allowed
to equilibrate at room temperature and pressure, as depicted in
step 118. The suspension, which includes amorphous metal hydroxide
M.sup.1(OH).sub.4 and metal peroxides M.sup.1(OOH).sub.4 and other
species such as, M.sup.1(Si--OH) and some condensation products of
these and other species, is stable, and can be stored at room
temperature for later use, dried to form a powder, vaporized to
form a vapor, or applied to a surface, as depicted in step 120.
[0085] A coating formed in step 120 can be treated later as desired
to change the chemistry or functionality of the coating. For
example, a coating formed in step 120 can be treated later to
enhance or impart catalytic, photocatalytic, anti-microbial,
anti-viral, anti-fungal, anti-corrosive, anti-fouling,
semi-conductive, conductive, insulative, electromagnetic,
transparent, optical, emissive, flame retardant, piezoelectric
properties, etc., or any combination thereof, to the coating.
Treatment can include, for example, incorporating additives (such
as nanoparticles) to a PMHNC composition, applying an additional
PMHNC composite coating, depositing an additional layer with
chemical vapor deposition (CVD) or atomic layer deposition (ALD),
employing soft lithography techniques, etc.
[0086] In step 122, the amorphous metal peroxide colloidal
suspension is, heated to boiling at a pressure greater than
atmospheric pressure for a suitable period of time. The composition
can be agitated during heating. The temperature at which the
suspension is heated can depend on several factors, including the
components present, in the mixture, the pressure, inside the
reaction vessel, and constraints associated with manufacturing. In
an example, an amorphous metal peroxide colloidal suspension having
a volume of about 2 liters can be heated to between about
45.degree. C. to about 250.degree. C. for about 11/2 to 2 hours at
a pressure of 10 to 100 pounds per square inch (psi). For larger
volumes of the mixture, for example, as used in manufacturing, the
pressure can be suitably higher, for example, up to 2500 psi.
During the heating and pressure application step, the properties of
the mixture (for instance, temperature, pH, etc.) can be monitored
to ensure that a substantially homogeneous solution is being
formed.
[0087] The amorphous metal peroxide/metal oxide composition formed
in step 122 may have a pH of about 7. Light transmissiveness of the
solution is about 92-98%; thus, it appears clear to the human eye.
Moreover, the density of the solution (that is, the amount of solid
dispersed in solution) can range from about 0.125% to about 2.0% or
higher, depending on intended use of the composition.
[0088] Organofunctional silanes, organometallic compounds, wetting
agents, and/or reactive or inert additives including nanoparticles,
composite PMHNC powders and vapors etc., such as described for
optional step 112 above, can be added as desired in optional step
124, before or during heating of the suspension in step 122.
Organofunctional silanes, organometallic compounds, wetting agents,
and/or reactive or inert additives, as present from optional steps
104, 112, and/or 124, can undergo hydrolysis and subsequent
condensation with metal hydroxide present in the composition to
form covalently bonded structures including, for example,
M(OOH).sub.xOM, and M(OOH).sub.xOM (where M can be M.sup.1,
M.sup.2, M.sup.3, or any combination thereof), along with M(Si--OH)
and oxides of M.sup.1, M.sup.2, and M.sup.3, while substantially
depleting the metal hydroxide present prior to reaction with the
peroxide-based solution. In some cases, similar covalently bonded
structures include reactive additives together with, or in place
of, metals M.sup.1, M.sup.2, and/or M.sup.3. These covalently
bonded structures function as inorganic binders for the creation of
nonporous coatings. In particular, as the composition is heated,
the metal peroxide reacts with the silane to improve crosslinking,
hardness, and abrasion resistant properties of the binder.
[0089] Substrates (or fillers) that are not able to covalently bond
with silanes alone (such as polyolefins and polyethers) or
demonstrate only a weak interaction with silanes alone (such as
CaSO.sub.4, BaSO.sub.4, inorganic pigments, carbon black, calcium
carbonate, and graphite) can be bound by silane-containing PMHNC
vehicle systems. For example, a PMHNC hybrid vehicle system in step
122 has exposed, non-reacted peroxy groups available to react with
additives able to undergo hydrolysis and condensation. The addition
of methacryloxy silane (such as
N-(3-acryloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane) in
step 124 creates a peroxide metal methacrylate composite vehicle
system with dual functionality such as M(OOH).sub.2(OR).sub.2,
(where R is the methacryloxy-silane, hydrolyzed and then condensed
onto the PMHS monomer), and thus forms colloidal-oligomers
dispersed in water. Since the hybrid colloidal oligomers are
dispersed in high percentages of water, such as approximately 98%,
the free peroxy groups on the oligomers thus maintain steric
stabilization.
[0090] When the composite vehicle system is applied to a surface
and the water evaporates, the peroxy groups act as a catalyst to
promote polymerization. In the case of PMHS oligomer formation, the
peroxide is an integral inorganic substituent of the PMHS. Thus,
the peroxide is also involved in the final polymerization through
hydrolysis and condensation as shown in FIG. 3. During
polymerization, one leg of the double bond of the methacryl
functionality breaks and links up with the middle carbon atom of
another methyl methacrylate molecule to start a chain, repeating
until the final hybrid polymer is formed. This type of coating
enhances coupling sites on substrates that demonstrate weak
interaction with silanes, and consequently improves tensile and
flexural properties by up to 50% over silane treatment alone.
Similarly, a PMHNC vehicle system can bind and stably disperse
other additives with weak (or substantially no) silane interaction,
such as carbon nanotubes, carbon black, graphite, calcium
carbonate, calcium sulfate, barium sulfate, inorganic pigments,
etc., in surprisingly high weight ratios.
[0091] When an organofunctional silane has been added in optional
step 112 and/or step 124, silanol groups undergo condensation
reactions with metal peroxides in an aqueous solution to form PMHS
monomers, in which the silicon bonds directly or indirectly (with
one or more intervening atoms, such as oxygen) to the metal atom in
the metal peroxide.
[0092] For organometallic compounds, such as those including zinc,
the reaction of, for example, Ti(OOH).sub.4+Zn(OOH).sub.4 in a
titanium peroxide mixture forms a composite, such as a matrix of
--Ti--O--Zn--O--Ti--O--Ti--O--Ti--O--Zn--O, with the formation of
anatase titanium oxide crystals in a PMHNC composition. In some
cases, depending on the nature of the organometallic compound and
the organofunctional silane, the silane enhances dispersion of the
organometallic compound in the PMHS composition, providing
increased steric stabilization of dispersions such as composite
nanoparticle dispersions.
[0093] In some implementations, metal alkoxides as well as
organofunctional silanes are partially hydrolyzed to form reactive
monomers which undergo polycondensation to form colloid-like
oligomers. Addition of one or more organofunctional silanes in step
104 of FIG. 1 yields a siloxy-peroxy hybrid film former. Hydrolysis
and condensation of the siloxy-peroxy hybrid film former is
depicted in FIG. 3, in which M.sup.1, M.sup.2, and M.sup.3 are
transition metals and R is an aliphatic or aromatic group. In some
embodiments, R includes heteroatoms such as oxygen, nitrogen,
sulfur, etc. The polymerization and crosslinking shown in FIG. 3
yield a hybrid, three-dimensional matrix, and drying promotes
additional crosslinking during film formation to form a
siloxy-peroxy hybrid film.
[0094] The composition from step 122 can be applied to a surface,
as depicted in step 126, to form a protective coating on or seal
the surface. During film formation, reactive silanol groups in the
PMHS monomers undergo condensation reactions with hydroxyl groups
on the surface of a substrate, bonding directly or indirectly (with
one or more intervening atoms, such as oxygen) with atoms on the
surface of the substrate. In some cases, metal atoms in
organometallic compounds incorporated in compositions bind directly
or indirectly to PMHS monomers, and further bind directly or
indirectly to a surface of a substrate to strengthen adhesion of
the coating to the substrate. Thus, the composition described
herein includes random monomeric/oligomeric networks that bind to
each other and to the substrate to form an inorganic polymeric
coating, layer, or film adhered to the substrate through covalent
bonds between metal and substrate (directly or indirectly, with one
or more intervening atoms), between silicon and substrate (directly
or indirectly, with one or more intervening atoms), and between
metal and silicon (directly or indirectly, with one or more
intervening atoms).
[0095] An inorganic vehicle system formed in step 122 can include
PMHNCs formulated for a variety of applications, including sealants
for substrates including metal, wood, plastic, glass, textile, etc.
The coating applied in step 126 can be used alone as a sealant to
protect the substrate from the environment or, in some cases, from
chemical properties of a second coating applied on top of the
sealant. The coating applied in step 126 can be treated (for
example, with electromagnetic radiation, heat, pressure, etc.) at a
later time to alter chemical and/or physical properties of the
coating.
[0096] Step 128 depicts continued boiling under pressure of the
composition formed in step 122. This continued heating under a
pressure greater than atmospheric pressure causes the metal
peroxides to break down and promotes crystal growth of metal oxide
particles, as well as additional oligomer formation and
crosslinking, as depicted in FIG. 3. Thus, the ratio of metal oxide
to metal peroxide in the solution increases. Depending on the metal
oxide present, and other components in the composition, certain
desirable properties of the composition formed in step 128 are
enhanced relative to the same properties of the composition formed
in step 122.
[0097] Boiling at a pressure greater than atmospheric pressure in
steps 122 and 128 effectively reduces the amount of time required
to form the metal oxide crystals from the suspension formed in step
116 and the metal peroxide/metal oxide composition formed in step
122 relative to the amount of time required at atmospheric
pressure. Furthermore, the resulting PMHNC compositions have a
tighter particle size distribution and exhibit a more transparent
coating than PMHNC compositions formed by boiling at atmospheric
pressure.
[0098] Temperature and pressure inside the reaction vessel in step
128 can be adjusted depending on the quantity of solution and the
components in the solution. In an example, 1-5 liters of amorphous
titanium peroxide/titanium oxide composition can be, heated to
between about 45.degree. C. and about 250.degree. C. under 10-100
psi of pressure for about 3 hours until the peroxides are
substantially depleted and metal oxide nanocrystals are the
dominant metal species. The transparent metal oxide composition can
be applied by, for example, coating, spraying, drying, ALD, soft
lithography (including microcontact printing (.mu.CP), replica
molding (REM), microtransfer molding (.mu.TM), micromolding
capillaries (MIMIC), solvent assisted micromolding (SAMIM), self
assembled monolayers (SAM)), or other method, to any suitable
surface.
[0099] For a density of about 1.2-1.5 wt % metal oxide, the
composition formed in step 128 can have a light transmissiveness of
about 87-93%, such that the solution appears clear to the human
eye. In some implementations, the density of the metal oxide
solution (that is, the amount of solid dispersed in solution) can
be anywhere between 0.5 to about 2.0 wt %, depending on the desired
use of the composition. The composition is a homogeneous dispersion
of stabilized metal oxide nanoparticles less than about 10 nm or
less than about 5 nm in diameter (for instance, about 0.3 mm to
about 7 nm in diameter, or about 2 ran to about 5 nm in diameter),
with enhanced film-forming/and or surface treatment capabilities
determined by the silanes, organometallic compounds, and other
components added in steps 104, 112, and/or 124.
[0100] One or more organofunctional silanes may also be added in
step 112 and/or step 124 during the process depicted in FIG. 1. In
some implementations, a first organofunctional silane is mixed with
aqueous amorphous metal hydroxide in step 112. After stabilization
of the resulting metal peroxide colloidal suspension, a second
organofunctional silane is added in step 124 before or during
boiling of the amorphous metal peroxide mixture under increased
pressure. The second organofunctional silane can be the same as or
different than the first organofunctional silane.
[0101] Zeta potentials of compositions depicted in FIG. 1 provide
an indication of stability of these compositions. Particles with a
high zeta potential of the same charge sign, either positive or
negative, will repel each other. Conventionally, a high zeta
potential is considered to be .ltoreq.-30 mV or .gtoreq.+30 mV. For
molecules and particles that are small enough, and of low enough
density to remain in suspension, a high zeta potential indicates
stability, i.e., the solution or dispersion does not tend to
aggregate. Mean zeta potentials of compositions described herein
range from about -25 mV to about -50 mV, for example, about -30 mV
or about -40 mV.
[0102] Compositions formed in steps 122 and 128 can be applied as
described above to any suitable surface and allowed to dry under
ambient conditions or in the presence of heat to form a coating on
the surface, as depicted in steps 126 and 130. A coating can be,
for instance, of monolayer thickness on the order of nanometers. In
some implementations, a thickness of the coating is about 2-10 nm,
about 3-8 nm, or about 4-6 nm. In other applications, a coating can
have a thickness of about 10 nm to about 1 .mu.m. For instance, a
coating can have a thickness of about 10 nm to about 800 nm, about
100 nm to about 600 nm, or about 200 nm to about 500 nm. These
coatings are continuous, covalently bonded, cross-linked, cured
polymeric films, with no visible presence of agglomerated,
non-continuous particles. In some implementations, a viscosity of a
composition formed in steps 122 and 128 is adjusted to form a
thicker layer or coating, for instance, on the order of microns or
thicker. Repeated application of one or more compositions can
result in a coating of a desired thickness and with a desired
number of layers with the same or different functionality.
[0103] Compositions can be vaporized in steps 126 and/or 130 to
allow vapor deposition, such as ALD, CVD, etc. to form a coating or
thin film of a desired thickness. Sequential deposition of
precursors of the same or different PMHNC formulations or
treatments of the films in ALD, allows atomic layer control of film
growth, resulting in conformal, defect-free monolayers chemically
bonded to the substrate, with a thickness ranging, in some cases,
from about 1 nm to about 500 nm. ALD is suitable for forming a
variety of thin films, including conductors, insulators, etc. on
patterned or non-patterned, porous or non-porous substrates.
Composition and thickness of a coating can be selected to achieve
suitable values for properties such as dielectric constant,
conductivity, refractive index, transparency, reactivity, etc. In
particular, pure high dielectric constant coatings essentially free
of carbon (organic) contamination or silicon dioxide contamination
can be achieved with the compositions described herein. The small
particle sizes in the composition prepared in step 128 make these
compositions particularly suitable for vapor deposition
processes.
[0104] In some implementations, PMHNC compositions of 0.005% to 10%
stabilized solids dispersed in water can be used to form
nanocomposite powder particulates less than about 100 nm in
diameter. These nanopowders or nanocomposite powders can be, added
to a PMHNC composition (for example, in steps 112 and/or 124) or
other dispersion to improve mechanical, physical, and/or chemical
properties of, for example, thermosets, thermoplastic extrusions,
organic pigment dispersions, etc. PMHNC composite powders can be
bonded to particulate substrates that are not readily dispersed
into the PMHNC vehicle systems, or to particles not readily
dispersed into, for example, thermoset or thermoplastic
systems.
[0105] In some implementations, as depicted in FIG. 4, more than
one coating is applied to a substrate. A first composition can be
applied to a substrate 400 and allowed to dry to form a first
coating 402 on the substrate. A second composition can then be
applied to the first coating 402 and allowed to dry to form a
second coating 404 adhered to the first coating 402. The second
composition can be the same as or different than the first
composition. The thickness of the first coating 402 can be
approximately the same as, or different than, the thickness of the
second coating 404.
[0106] Similarly, as depicted in FIG. 5, a first composition can be
applied to a particle 500 or plurality of particles and allowed to
dry to form a first coating 502 on the particle. The particle can
be, for instance, a microparticle. A second composition can then be
applied to the first coating 502 and allowed to dry to form a
second coating 504 adhered to the first coating 502. The second
composition can be the same as or different than the first
composition. The thickness of the first coating 502 can be
approximately the same as, or different than, the thickness of the
second coating 504.
[0107] In some embodiments, a coated substrate is treated further
to alter properties of the coating. Treatment of a coated substrate
to alter the properties of the substrate is depicted by step 132 in
FIG. 1. In some implementations, coatings formed in steps 114, 120,
and/or 126 can be treated after formation of the coatings in
addition to, or independently of, treatment of a coated substrate
formed in step 132.
[0108] Organometallics added in steps 104, 112, and/or 124 impart
specific, desirable properties to PMHNC compositions. Some
non-limiting examples are described below.
[0109] Zirconium 2,4-pentanedionate is useful in the formation of
high dielectric constant layers of metal oxides (for example, by
ALD) containing Group 4 metals, including hafnium oxide. Zirconium
oxides resulting from incorporation of zirconium 2,4-pentanedionate
in PMHNC compositions impart hardness and scratch resistance to
PMHNC coatings.
[0110] Zinc 2,4-pentanedionate hydrate and zinc methoxyoxide, when
incorporated in TiO.sub.2 PMHNC compositions, form Ti/Zn composite
films with improved photocatalytic properties relative to
photocatalytic properties of Ti films. These compounds can be used
in the formation of transparent, conductive ZnO--In.sub.2O.sub.3
films and employed in sol-gel production of lead zirconate titanate
films, sol-gel coating of alumina powders in composites, and
preparation of clear monolithic poly(tetramethyleneoxide)ceramers.
These compounds can also be used as catalysts for simultaneous
polymerization and esterification and as components in high
refractive index, abrasion-resistant, and corrosion-resistant
coatings. The resulting zinc oxide is a refractory material.
[0111] Yttrium 2,4-pentanedionate can be added to a PMHNC vehicle
system to facilitate preparation of nanocomposite thin films
including yttrium oxide mixed with other oxide components. In some
cases, yttrium oxides impart superconductor-like properties to
coatings formed from compositions including yttrium.
[0112] Tungsten(V) ethoxide and/or tungsten(VI) ethoxide can be
added to PMHNC compositions to form tungsten nanoparticles and
composites useful in electronic and light-emitting applications.
Tungsten nanoparticles and composites can help achieve a thermal
coefficient of expansion similar to compositions including silicon
and other metals used in microelectronics. Nanomaterial inks and
pastes including tungsten can be useful in preparing improved DRAM
chips, other silicon devices, and liquid crystal display
products.
[0113] Titanium ethoxide can be incorporated into PMHNC
compositions to enhance photocatalytic properties, and serve as a
high-k dielectric gate material for SiO.sub.2 replacement. When
added in step 112 of the process depicted in FIG. 1, titanium
ethoxide increases the concentration of TiO.sub.2 into the crystal
lattice during film formation.
[0114] Titanium dioxide plays a complex role in durability in a
variety of coating compositions, such as paint. TiO.sub.2 is a
photocatalyst that absorbs ultraviolet light, thereby protecting
other components in a coating composition that break down under
exposure to ultraviolet light. Desirable coating compositions
enhance binder protection and reduce photocatalytic activity. PMHNC
compositions with titanium are capable of improving pigment
dispersion loadings, especially for organic pigments such as
phthalocyanine blue in waterborne dispersions. Copper
phthalocyanine is non-polar, like other organic pigments that
exhibit a resonance structure with amine functionality (e.g.,
perylene, quinacridone, etc.). By stabilizing expensive organic
pigment dispersions, lower loadings can be achieved, along with an
improvement in chromaticity (color richness or intensity) at a
significantly lower cost.
[0115] Tantalum(Y) ethoxide can be added to a PMHNC composition to
be used in ALD formation of high-k dielectric layers of metal
oxides containing Group 4 metals, including hafnium oxide, as a
gate material.
[0116] Tin(II) methoxide is useful in preparation of
nano-particulate tin-containing PMHNC compositions. The tin oxide
in the resulting coating provides fire-retardant and catalytic
properties, and is also useful in ion exchange systems and
electroconductive powders and films.
[0117] Silver(I) 2,4-pentanedionate, added in steps 112 and/or 124
of the process depicted in FIG. 1, provides antiseptic properties
and enhances photocatalytic characteristics of coatings formed with
PMHNC vehicle systems. Films formed with a silver(I)
2,4-pentanedionate component are transparent and, in some cases,
conductive. Similarly, gold, platinum, and palladium organics can
also be incorporated to provide conductive properties as needed,
for example, in the case of thin film electrodes, catalyst
supports, etc. Platinum 2,4-pentanedionate can be incorporated in a
composition for a transparent electrode for use in, for example, a
dye-sensitized solar cell. Platinum 2,4-pentanedionate can also be
added to form a composite Ti/Si with bis silane as a mesoporous
nanocoating for a catalytic converter.
[0118] Samarium 2,4-pentanedionate can be used in PMHNC
compositions to form thin films including samarium oxide. Samarium
oxide facilitates dehydration and dehydrogenation of ethanol. A
nano-layer PMHNC coating with samarium oxide, incorporated over a
microporous glass filter, provides increased surface area for
reaction as ethanol passes through the filter.
[0119] Praseodymium 2,4-pentanedionate can be incorporated into a
PMHNC composition to form a titanate nanofilim composite for
electronic devices, with a layer succession of
metal-insulator-metal or metal-insulator-semiconductor used as
memory cells in memory devices such as DRAMs (dynamic random access
memory) or as passive components in high-frequency
applications.
[0120] Nickel(II) 2,4-pentanedionate can be added to a PMHNC
composition to provide properties such as, for example, corrosion
inhibition and catalytic activity. The resulting film can act as a
catalyst for conjugate addition of alkynyl aluminum to enones,
coupling of Grignard reagents to form biaryls, Grignard additions
to silyl enol ethers to form alkenes, and coupling of dialkylzincs
with alkyl iodides. The resulting film can also provide a
thermochromic effect in non-coordinating solvents and act as a UV
stabilizer for polyphenylene sulfide.
[0121] Addition of neodymium (III) 2,4-pentanedionate to a PMHNC
composition forms ferroelectric titanates in a PMHNC film. When
added to a PMHNC composition, molybdenum(V) ethoxide yields
molybdenum oxides in the resulting films, which are useful in
electrochemical devices and displays.
[0122] The structure of ordered porous manganese-based octahedral
molecular sieves (OMS) is governed by the type of aggregation (for
instance, corner-sharing, edge-sharing, or face-sharing) of the
MnO.sub.6 octahedra. The ability of manganese to adopt multiple
oxidation states and of the MnO.sub.6 octahedra to aggregate in
different arrangements allows formation of a large variety of OMS
structures. Addition of manganese(II) 2,4-pentanedionate to PMHNC
compositions can promote incorporation of manganese oxide and
MnO.sub.6 octahedra into films that bond to substrates under
ambient conditions. In some cases, PMHNC films containing manganese
oxide can be used as ion intercalation hosts in lithium ion
batteries.
[0123] Addition of magnesium 2,4-pentanedionate to a PMHNC
composition results in a film with catalytic properties. A PMHNC
film with magnesium oxide can be used as a catalyst for
polymerization of olefins and/or thickening reactions of
polyesters.
[0124] Incorporation of magnesium ethoxide into step 104, 112,
and/or 124 of the process depicted in FIG. 1 results in composite
formation with TiO.sub.2 to create spinels that can be used for
high refractory thin film crucible linings and gas permeable
inorganic membranes.
[0125] Addition of magnesium methoxide to a PMHNC composition
results in the formation of films containing magnesium oxide
(magnesia). Magnesia has a high coefficient of thermal expansion
that makes this oxide especially suitable for a porous structure
for use as a support for an inorganic membrane with a comparable
coefficient of thermal expansion. Magnesia is a substantially pure
phase refractory ceramic with a high coefficient of thermal
expansion, and therefore imparts unique characteristics to a PMHNC
coating. PMHNC coatings with magnesium oxide can be used, for
example, in magnetic core windings and in other applications
including production of fluorophlogopite and applications in which
the dielectric constant of magnesium oxide and optical properties
of sol-gel derived therefrom are desirable. In some cases, a PMHNC
coating with magnesium oxide can be used to deacidify paper.
[0126] Addition of lithium 2,4-pentanedionate in the process
depicted in FIG. 1 yields nano lithium composite films and powders.
The resulting small particle size and narrow size distribution are
advantageous for use as electrodes for lithium ion batteries,
allowing the batteries to retain their charging capacity at high
charging and discharging rates.
[0127] When the process depicted in FIG. 1 includes lanthanum
2,4-pentanedionate, the resulting PMHNC film includes lanthanum
oxide and is suitable as a high-k dielectric gate material. These
films can be intermediates for ferroelectrics and sol-gel derived
superconductors.
[0128] In the presence of selected yttrium compounds, lanthanum
methoxyethoxide forms LaYO.sub.3 in PMHNC films. LaYO.sub.3 can be
used as an exhaust catalyst or, with other components, in the
formation of an oxidation resistant coating.
[0129] Addition of lanthanum isopropoxide to a PMHNC composition
results in low leakage dielectric films. A coating including
lanthanum oxide as a dielectric layer has a relatively high
dielectric constant, a relatively high conduction band offset, and
a high crystallization temperature.
[0130] Addition of indium 2,4-pentanedionate and/or indium
methoxyethoxide in the process depicted in FIG. 1 results in the
formation of clear, electrically conductive films that can be used
in field effect transistors.
[0131] PMHNC compositions including hafnium 2,4-pentanedionate
and/or hafnium ethoxide yield refractory coatings and films with
high-k dielectric layers including hafnium oxide.
[0132] When added to PMHNC compositions, gallium(III)
2,4-pentanedionate and gallium(III) ethoxide yield films including
gallium oxide nanocrystals. Films with gallium oxide nanocrystals
are useful for opto-electronic devices and gas-sensing and
catalytic applications. Cohydrolysis of gallium(III) ethoxide with
tellurium alkoxides in a PMHNC vehicle system yields films that are
useful in heat-mode erasable optical memory.
[0133] PMHNC compositions made with gadolinium 2,4-pentanedionate
trihydrate yields films suitable for controlling or containing
radioactive contamination by providing a neutron absorbing material
to a radioactive contamination site.
[0134] Iron (III) 2,4-pentanedionate and iron (III) ethoxide, when
added in the process depicted in FIG. 1, act as intermediates for
sol-gel formation of ferrites. Coatings with the resulting iron
oxides yields catalytic coatings and coatings with magnetic
properties. Iron (III) ethoxide reacts with other components to
form iron oxide and other products. For example, iron (III)
ethoxide reacts with platinum, to yield FePt nanoparticles. In some
cases, films including iron oxides are useful as intercalation
hosts in lithium ion batteries.
[0135] In some embodiments, addition of europium 2,4-pentanedionate
to a PMHNC composition yields coatings with fluorescent
properties.
[0136] Erbium oxide provides a pink coloration to films produced
from vehicle systems made with the addition of erbium
2,4-pentanedionate.
[0137] PMHNC compositions with dysprosium oxide derived from
dysprosium 2,4-pentane-dionate are suitable for ALD.
[0138] Addition of copper(II) 2,4-pentanedionate and copper(II)
ethoxide to PMHNC compositions yields films useful in
electrochemical and superconducting applications.
[0139] When incorporated into PMHNC compositions, cobalt(III)
2,4-pentanedionate serves as a catalyst in a range of
polymerization reactions that facilitate film formation. This
organometallic compound also has applications in the preparation of
light-sensitive photographic materials.
[0140] Nanoparticles derived from the addition of chromium(III)
2,4-pentanedionate to PMHNC compositions are incorporated into a
crystalline matrix during film formation. In some cases, films with
chromium oxides demonstrate catalytic properties.
[0141] Cesium 2,4-pentanedionate can be used in the preparation of
PMHNC compositions to yield films useful for field emission
displays. Resulting films with cesium oxide are useful as
conductive layers in forming electrodes for electronic devices.
[0142] When added to PMHNC compositions, cerium 2,4-pentanedionate
yields coatings with cerium oxide. Coatings with cerium oxide
absorb UV radiation and can also be used as a high-k dielectric
gate material.
[0143] Boron ethoxide is useful in the formation of boron oxide
nanocomposites for nanofilms and nanopowders. PMHNC compositions
with boron can be used as CVD precursors for boron-modified
SiO.sub.2 in microelectronics.
[0144] Bismuth(III) t-pentoxide can be added to PMHNC compositions
to yield films with bismuth oxide. Films with bismuth oxide are
characterized by x-ray opacity and radiofrequency opacity. Films
with bismuth oxide can also be used in the manufacture of varistors
and in the coating of microparticle plastics for extrusion.
[0145] Aluminum(III) 2,4-pentanedionate can be used in the
formation of high-k dielectrics by ALD.
[0146] In some embodiments, PMHNC films with barium oxide derived
from barium 2,4-pentanedionate, are useful as intermediates for
sol-gel derived superconductors.
[0147] Addition of beryllium 2,4-pentanedionate to a PMHNC
composition, in some cases, yields high, thermal conductivity
ceramic coatings.
[0148] PMHNC films with cadmium oxide, derived from the addition of
cadmium 2,4-pentanedionate, are transparent to infrared radiation,
and exhibit light-emitting and conductive properties.
[0149] Addition of calcium 2,4-pentanedionate to PMHNC compositions
facilitates coating of glass microparticles with thin films to
achieve a desirable melt effect.
[0150] Incorporation of iridium oxide into PMHNC coatings through
the addition of iridium(III) 2,4-pentanedionate yields, films with
catalytic and/or photoreducing properties.
[0151] Other suitable organometallics for addition to PMHNC
compositions include, but are not limited to, lithium ethoxide,
vanadium(III) pentanedionate, tin(II) 2,4-pentanedionate, palladium
2,4-pentanedionate, holmium 2,4-pentanedionate, antimony(III)
ethoxide, and barium(II) methoxypropoxide.
[0152] In addition to the metal oxides formed in the process
depicted in FIG. 1, a variety of metal oxides, sulfides,
phosphides, arsenides, etc. can be added in steps 104, 112, and/or
124 to enhance selected properties of a PMHNC composition. Metals
suitable inclusion as oxides, sulfides, phosphides, arsenides, etc.
include, for example, titanium, zirconium, zinc, strontium,
cadmium, calcium, indium, barium, potassium, iron, tantalum,
tungsten, samarium, bismuth, nickel, copper, silicon, molybdenum,
ruthenium, cerium, yttrium, vanadium, tellurium, tantalum, tin,
silver, scandium, praseodymium, niobium, neodymium, manganese,
magnesium, leutium, lithium, lanthanum, holmium, hafnium,
germanium, gallium, gadolinium, europium, erbium, dysprosium,
cobalt, chromium, cesium, boron, aluminum, antimony, lead, barium,
beryllium, iridium, and the like, or any combination thereof.
[0153] The above compounds can be added to a PMHNC composition in a
step in FIG. 1 or formed during the process depicted in FIG. 1.
Advantages, properties, and uses of various oxides and other
compounds in coatings and nanopowders formed from PMHNC
compositions are described below. Macroscopic properties of these
compounds are indicative of the characteristics they demonstrate on
a molecular level when bound in a PMHNC coating or nanopowder.
[0154] Zirconium oxide and yttrium stabilized zirconium oxide are
hard white, amorphous powders, useful in pigments, refractory
materials, and ceramics. Zinc oxides are also useful in refractory
materials, ad demonstrate a thermal expansion less than that of
alumina, magnesia, and zirconia. These oxides provide abrasion
resistance and corrosion resistance to PMHNC coatings.
[0155] In PMHNC films, yttrium oxide is useful as a catalyst, a
colorant, a flux, and a dye, and has fire-retardant properties.
[0156] Tungsten oxide can be added to PMHNC compositions as a
pigment, an opacifying agent, and/or a catalyst. It is desirable in
optical coatings, welding rod fluxes, ceramic finish coats,
plastics, elastomers, coated fabrics, printing inks, roofing
granules, glass, and glazes.
[0157] In PMHNC films, titanium oxide, titanium dioxide, and
tantalum pentoxide provide high index, low absorption material
usable for coatings in near ultraviolet to infrared regions. Dense
layers or multilayers can be used. Titanium oxide/dioxide and
tantalum pentoxide can be used together with silicon dioxide to
form hard, scratch-resistant, adherent coatings. Films with
titanium oxide/dioxide can also be used as dielectrics in film
capacitors and as gate insulators in LSI circuits requiring low
leakage voltage characteristics. Tantalum pentoxide also
demonstrates ferroelectric properties. Tantalum oxides are useful
in PMHNC compositions as opacifiers and pigments and are beneficial
in applications including ceramics, capacitors, and conductive
coatings.
[0158] When added to PMHNC compositions, silicon monoxide powder
can provide anti-reflective and/or interference properties. In some
cases, silicon monoxide powder is used with ZnS and other materials
to form reflective coatings. Films with SiO can be used in
electronics applications, such as thin-film capacitors, hybrid
circuits, and semiconductor components, with a variety of
insulating and dielectric properties determined by film thickness.
Incorporated in PMHNC films, SiO adds corrosion and wear
resistance, and can be used as a filler in a variety of
applications. Silicon dioxide, synthetic silicon dioxide, silicate
powder, silica sand, quartz sand and powder, amorphous silica, and
silica aerogels can also be added to PMHNC compositions (for
instance, compositions including ZrSiO.sub.2/TiO.sub.2) to form
high-k films and enhance heat and thermal shock resistance. These
films are also useful in electronic ceramics.
[0159] Scandium oxide can be added to PMHNC compositions to provide
a yellow coloration or enhance magnetic properties.
[0160] In PMHNC compositions, nickel oxides act as corrosion
inhibitors and/or oxygen donors, and can react with molybdenum
compounds to form nickel molybdate. Films including nickel oxides
are useful in thermistors, varistors, cermets, resistance heating
elements, ceramic glazes, enamels, and pigments.
[0161] When added to PMHNC compositions, niobium oxide enhances
properties related to use in ceramic capacitors, glazes, and
colored glass.
[0162] Addition of micaceous iron oxide to a PMHNC composition
yields coatings with durable, corrosion-resistant properties that
reflect ultraviolet light. A PMHNC nanopowder with micaceous iron
oxide can be dispersed in paints, primers, or other coating
compositions to add increased corrosion- and weather-resistance.
The horizontal layering and overlapping of the lamellar (micaceous)
particles strengthens the coating compositions and acts as a
barrier to the penetration of corrosive elements and ultraviolet
light.
[0163] In some implementations, manganese oxide powder (MnO.sub.2)
is added to PMHNC compositions as a colorant or decolorizer. MnO
provides ferromagnetic and catalytic properties to PMHNC
coatings.
[0164] Magnetite/black iron oxide powder is a natural iron oxide
magnet. When added to PMHNC compositions, the resulting coatings
are useful as refractory materials, absorbent coatings, catalytic
coatings, and catalyst supports. PMHNC nanopowders with iron oxide
can be used in cements, fertilizers, gas-scrubbing applications,
etc.
[0165] When added to PMHNC compositions, specular hematite
(Fe.sub.2O.sub.3) will aid in resistance to corrosion, including
rusting and oxidation, thus allowing flow of a composition through
a metering valve without staining or clogging. Furthermore,
Fe.sub.2O.sub.3 will add non-hygroscopic properties to a PMHNC
film, and is useful in steel manufacture or as a colorant and/or
coating for rubber, adhesives, plastics, concrete, and iron.
[0166] PMHNC compositions with lutetium oxide powder and/or
lanthanum oxide powder exhibit desirable optical properties.
Applications include X-ray image intensifying screens, phosphors,
dielectric ceramics, conductive ceramics, and barium titanate
capacitors.
[0167] Indium tin oxide powder is a transparent, conducting
material with a variety of applications in display devices,
photovoltaic devices and heat reflecting mirrors. PMHNC
compositions with indium tin oxide can be used in flat panel
display applications, glass manufacturing techniques,
electroluminescent display applications, plasma display panel
applications, electrochromic display applications, field emission
display applications, and transparent coatings. PMHNC compositions
with indium oxide enhance resistive elements in integrated
circuits, sputtering targets, and conductive inks.
[0168] In PMHNC compositions, hafnium oxide powder adds properties
desirable for refractory material and gate oxides.
[0169] In some embodiments, addition of germanium oxide powder to
PMHNC compositions yields coatings for optical glass.
[0170] Gallium oxide powder can be used in PMHNC coatings as a
chemical intermediate or as an enhancement for compositions or
coatings used in semiconductor electronics, such as piezoelectric
resonators and transducers.
[0171] Gadolinium oxide powder is used as a raw material for
various fluorescent compounds, absorption material in atomic
reactions, magnetic bubble material, screen-sensitivity increasing
material, as well as in many other applications in the chemical,
glass, and electronics industries. Similar benefits are apparent
upon incorporation of gadolinium oxide powder in PMHNC coatings and
nanopowders.
[0172] Addition of copper oxide powder to a PMHNC composition
provides, a red pigment to PMHNC films and nanopowders, and imparts
anti-fouling properties.
[0173] A PMHNC with chromium dioxide powder can be used as an
additive to bricks, pigments and mortars to increase the life of
the these materials.
[0174] When present, in PMHNC coatings and nanopowders, boric oxide
powder acts as a flame retardant and corrosion inhibitor. Boron
oxide powder acts as a acid catalyst or chemical intermediate in
production of different boron compounds.
[0175] Boehmite alumina powder (AlO(OH)) and alumina powder
(Al.sub.2O.sub.3) are used in refractories, abrasives, cement, slag
adjusters, ceramics, aluminum chemicals, flame retardants, fillers,
welding fluxes, adsorbents, adhesives, coatings, and detergent
zeolites. Addition of boehmite alumina powder to PMHNC compositions
imparts desirable properties on a nano scale to PMHNC coatings and
nanopowders for similar uses.
[0176] Similarly, bismuth oxide powder is used in optical glasses,
fluxes, varistor formulations, ceramic capacitor formulations, and
as a replacement for lead oxide in whitewares (bone china, etc.).
Addition of bismuth oxide powder to PMHNC compositions imparts
desirable properties on a nano scale to PMHNC coatings and
nanopowders for similar uses.
[0177] When added to PMHNC compositions, antimony tin oxide adds
properties favorable for use in optics and electronics,
particularly in display panels, due to antistatic properties,
infrared absorbance, transparency, and conductivity.
[0178] Antimony oxide powder imparts flame retardant properties to
PMHNC compositions.
[0179] Coatings from PMHNC compositions that include fused aluminum
oxide powder demonstrate increased abrasion resistance. These
compositions are also useful as refractory coatings.
[0180] Other oxides useful in PMHNC compositions include, but are
not limited to, ruthenium oxide, beryllium oxide, cadmium oxide,
calcium oxide, vanadium oxide, samarium oxide, neodymium oxide,
molybdenum oxide, praseodymium oxide, ferric iron hydroxide,
lithium oxide, holmium oxide, europium oxide, cerium oxide, and
aluminum oxide.
[0181] Various titanites can be added to PMHNC compositions to
impart desired properties to coatings and nanopowders formed from
the compositions. For example, crystalline strontium titanite is a
high dielectric constant material that can be incorporated into a
PMHNC film for uses a dielectric gate material for SiO.sub.2
replacement. PMHNC compositions with lead zirconate titanate can be
useful in the field of transducers, both for loudspeakers and
microphones. When added to PMHNC compositions, barium titanate
enhances coatings for use with ferroelectric ceramics, single
crystals, storage devices, and dielectric amplifiers.
[0182] The following non-limiting examples describe various stages
of preparation of PMHNC compositions.
[0183] Hybrid metal oxides including silicon can be formed with one
or more additional metal salts in other embodiments as well. For
example, when a silicon halide and one or more additional metal
salts are added in step 102, or step 102 and step 104, the
resulting vehicle systems include hybrid metal oxides of silicon
and any of M.sup.1, M.sup.2, or any combination thereof. Exemplary
hybrid metal oxides include [SiO.sub.x:TiO.sub.y],
[TiO.sub.y:SiO.sub.x], [SiO.sub.x:ZrO.sub.z],
[SiO.sub.x:ZrO.sub.z:TiO.sub.y], [SiO.sub.x:ZrO.sub.z:TiO.sub.y],
and [TiO.sub.y:ZrO.sub.z:SiO.sub.x]. As used herein, hybrid metal
oxides are expressed as wt % ratios in descending order, with 100
wt % representing the total weight of the metal oxides in the
composition to be applied to a substrate. Thus, a vehicle system
that includes 19 wt % zirconium oxide, 1 wt % titanium oxide, and
80 wt % silicon oxide, is expressed as a
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] hybrid, and a system that includes
98 wt % titanium oxide and 2 wt % silicon oxide is expressed as a
[TiO.sub.y:SiO.sub.x] hybrid. SiO.sub.x, TiO.sub.y, and ZrO.sub.z
are referred to herein as "metal oxides," and can represent various
molar ratios of metal to oxygen. In some embodiments, an oxide may
be a dioxide.
[0184] The characteristics of these vehicle systems allow for
hybrid metal oxide coatings to be applied to a wide array of
substrates at room temperature to form inorganic, polymeric thin
films on the substrate. Depending on the composition of the vehicle
system, hybrid metal oxide coatings may be hydrophilic or
hydrophobic without further treatment following film formation.
That is, once the coating is dry, additional treatment such as, for
example, irradiation with UV light, is not required to achieve the
desired hydrophobic/hydrophilic characteristics. As used herein, a
"hydrophilic" surface has a contact angle with water of less than
about 20.degree., less than about 10.degree., or less than about
5.degree.. As used herein, a "hydrophobic" surface has a contact
angle with water of at least about 90.degree..
[0185] In an example, an aqueous hybrid metal oxide composition
with more than 50 wt % of titanium oxide (expressed herein as
[TiO.sub.y:SiO.sub.x], [TiO.sub.y:SiO.sub.x:MO.sub.z],
[TiO.sub.y:MO.sub.z:SiO.sub.x], etc.), forms a hydrophilic coating
that will absorb water and repel non-polar solvents such as
toluene. For an aqueous hybrid metal oxide composition including
greater than 50 wt % of silicon oxide (expressed herein as
[SiO.sub.x:TiO.sub.y], [SiO.sub.x:TiO.sub.y:MO.sub.z],
[SiO.sub.x:TiO.sub.y:MO.sub.z], etc.), the vehicle system forms a
hydrophobic coating that will repel hydrophilic polar solvents such
as water.
[0186] A hydrophobic coating imparts anti-corrosive properties to a
substrate, repelling water and causing water droplets to bead up on
the surface of the coating rather than allowing the coating to
absorb the water. Thus, a hydrophobic coating can form an
anti-corrosive coating for metal substrates, while a hydrophilic
coating allows water to contact the substrate and contribute to
electrochemical corrosion.
[0187] Hydrophobic coatings formed from silicon-titanium hybrid
metal oxide vehicle systems can include, for example, greater than
50 wt % silicon oxide and less than 50 wt % titanium oxide.
Examples include SiO.sub.x:TiO.sub.y of about 80:20, about 95:5,
about 98:2, about 99:1, and about 99.99:0.01. Hydrophobic coatings
formed from a hybrid metal oxide vehicle system including silicon,
titanium, and zirconium can include greater than 50 wt % silicon
oxide, with the sum of titanium and zirconium oxides less than 50
wt %. As an example, a ratio of [SiO.sub.x:ZrO.sub.z:TiO.sub.y] can
be about 80:19:1 for a non-photocatalytic coating. In some cases,
titanium is absent, resulting in a [SiO.sub.x:ZrO.sub.z] vehicle
system.
[0188] Hydrophilic coatings formed from titanium-silicon hybrid
metal oxide vehicle systems can include, for example, greater than
50 wt % titanium oxide and less than 50 wt % silicon oxide.
Examples include TiO.sub.y:SiO.sub.x of about 80:20, about 95:5,
about 98:2, about 99:1, and about 99.99:0.01. Hydrophilic coatings
formed from a hybrid metal oxide vehicle system including titanium,
silicon, and zirconium can include greater than 50 wt % titanium
oxide, with the sum of silicon oxide and zirconium oxide less than
50 wt %. In some cases, silicon is absent, resulting in a
[TiO.sub.y:ZrO.sub.z] vehicle system.
[0189] Optimal solids content and film forming, binding, and
stability properties of the vehicle systems are achieved by careful
attention to factors such as chloride and ammonium ion
concentration, amount of peroxide added, pH at various stages,
pressurization during heating, and heating and cooling
temperatures, described above with reference to FIG. 1. The
resulting vehicle systems function as binders and film formers for
hybrid metal oxide nanoparticles stabilized in solution. The
nanoparticles are advantageously formed to have very small particle
size and exhibit a high zeta potential.
[0190] In particular, the ammonium ion concentration is related to
the pH of the mixtures formed during the process. Chloride ion
removal to less than about 2 ppm, or less than about 1 ppm,
together with an effective ammonium ion concentration, promotes
formation of stable vehicle systems. The weight ratio of peroxide
added to the solids of the colloidal suspension following chloride
ion removal can be about 30.+-.20%, for example about 28-33%. The
pH values vary throughout the process from below 1 in step 102 of
FIG. 1, up to 9 or up to 11.5 prior to chloride ion removal in step
108, and down to 4 or below following peroxide addition in step
116. In step 118, the mixture is slightly acidic, with a pH between
about 5 and 7. The vehicle system resulting from step 128 is nearly
neutral, ranging from about 7.0 to about 7.5 or from about 7.0 to
about 10, depending upon the pH of neutralization in step 106. FIG.
1 is described below in detail for [TiO.sub.y:SiO.sub.x:MO.sub.z]
vehicle systems in which the weight ratio of titanium oxide exceeds
the sum of the weight ratios of silicon oxide and other metal
oxide. MO.sub.z (e.g., ZrO.sub.z) can be present or absent. For the
sake of simplicity, MO.sub.z is not considered to be present in
this exemplary illustration. Measured indicators such as pH, heat
evolved, etc. for [TiO.sub.y:SiO.sub.x] vehicle systems differ from
the indicators for [SiO.sub.x:TiO.sub.y] vehicle systems based upon
the resulting reactions through similar processing steps.
[0191] An acidic, aqueous mixture of titanium tetrachloride and
silicon tetrachloride is formed in step 102. The pH of the mixture
starts out below 1 and increases steadily toward a neutral pH of
about 7.5 to about 11.5, depending upon molar ratio of titanium and
silicon present in solution. During neutralization with ammonium
hydroxide in step 106, hydroxides of titanium and silicon float out
of the colloidal suspension and readily disperse back into
suspension with mild agitation. The flakes appear sparsely
throughout the neutralization process. The heat released in the
neutralization reaction evolves steadily as the reaction proceeds.
After neutralization, the metal hydroxide mixture is an opaque
white with a seaglass greenish tint.
[0192] Once neutralized, the mixture stabilizes in about 24 hours
or less (e.g., about 12 hours or less, about 8 hours or less, or
about 4 hours or less). The suspended particles form light, fluffy
agglomerates thought to be held together by van der Waals forces.
The flocculated particles settle rapidly, forming a loosely
adhering mass. At this point in the process, the colloidal
suspension can be packaged in a container and transported. The
particles may settle out during transportation, and can be
re-suspended with gentle agitation.
[0193] Steps 108-116 may be followed as described above. After the
last filtration/decantation in step 108, one or more of a variety
of ion exchange resins can be added to the suspension to facilitate
removal of chloride ions. The chloride ions are effectively
replaced by ammonium ions (e.g., including some from the ion
exchange resin), raising the pH and preparing the colloidal
suspension in step 110 for addition of peroxide in step 116. The
suspension is cooled to a temperature below about 10.degree. C.
prior to peroxide addition. During peroxide addition, cooling is
used to control and stabilize the rate of the exothermic reaction
of metal hydroxides with peroxide to form metal peroxides. Addition
of about 30.+-.20 wt %, for example about 25-35 wt % or about 30-33
wt % peroxide, based on colloidal solids, causes a decrease in pH
of the mixture to about 2 or below. Steps 118-128 may be followed
to form a sterically stabilized [TiO.sub.y:SiO.sub.x] vehicle
system.
[0194] The sterically stabilized [TiO.sub.y:SiO.sub.x] vehicle
system can be applied to a substrate and allowed to dry under
ambient conditions. Hydrolysis and condensation reactions occur
during drying, resulting in formation of a hybrid metal oxide
coating or film on the substrate. The condensation reactions
include, for example, binding of a peroxide to a surface hydroxyl
group with the elimination of water, binding of one peroxide to
another peroxide, etc. The hybrid metal oxide coating is polymeric,
hydrophilic, and may be photocatalytic, depending on the presence
of photocatalytic species such as anatase titanium dioxide.
[0195] FIG. 1 is described below in detail for
[SiO.sub.x:TiO.sub.y:MO.sub.z] vehicle systems in which the weight
percentage of silicon oxide (SiO.sub.x) exceeds the weight percent
of TiO.sub.y in the composition to be applied to a substrate.
MO.sub.z (e.g., ZrO.sub.z) can be present or absent. For the sake
of simplicity, MO.sub.z is not considered to be present in this
example.
[0196] An acidic, aqueous mixture of titanium tetrachloride and
silicon tetrachloride is formed in step 102. A pH of the mixture is
less than about 1. The amount of base required for neutralization
and the shape of the titration curve are dependent upon the weight
ratio of silicon oxide to titanium oxide (i.e.,
[SiO.sub.x:TiO.sub.y]). A [SiO.sub.x:TiO.sub.y] vehicle system,
which results in a hydrophobic coating, requires less base (e.g.,
about 1/3 less) and results in a higher pH when neutralized than a
[TiO.sub.x:SiO.sub.y] vehicle system, which results in a
hydrophilic coating. During neutralization with ammonium hydroxide
in step 106, hydroxides of titanium and silicon float out of the
colloidal suspension and readily disperse back, in suspension with
mild agitation. The flakes appear sparsely throughout the
neutralization process. Heat evolves non-linearly during
neutralization with more heat released as the pH approaches 7 than
is observed for a [TiO.sub.x:SiO.sub.y] vehicle system. Base is
added until the pH of the mixture is between about 7.0 and 8.0
(e.g., about 7.5 or about 7.65) or between about 7.0 and 11.5. The
silicon hydroxide is more soluble at higher pH. Thus, a higher pH
may be desirable for systems with a higher percentage of silicon.
After neutralization, the metal hydroxide suspension in which the
molar ratio of silicon is higher than the molar ratio of titanium
is opaque and white with a translucent aqua green tint, indicating
a smaller colloidal mean particle size distribution than the
greenish metal hydroxide mixture in which the molar ratio of
titanium is higher than the molar ratio of silicon.
[0197] Upon standing at room temperature for about 12 hours, the pH
of the mixture is between about 7.0 and 8.5 (e.g., about 7.6 or
about 8.2) or between about 7.0 and 11.5, and may vary from the
bottom of the vessel to the top of the vessel containing the
mixture. A single pH value can be obtained following sufficient
agitation to form a homogeneous suspension. The suspended particles
form light, fluffy agglomerates thought to be held together by van
der Waals forces. The flocculated particles settle rapidly to form
a loosely adhering mass. The particles can be re-suspended with
gentle agitation.
[0198] Effective chloride ion removal is achieved during filtration
or decantation, followed by reconstitution or resuspension in step
108. Filtration, such as with a Nutsche filter, may allow for
quantitative separation, as well as incorporation of additives such
as silanes, organometallics, monomers, nanoparticles etc., in a
solid, liquid, or gaseous phase to react with the gelatinous clay,
while decantation is advantageously rapid. The advantages of
decantation may be less apparent in the filtration of a hydrophobic
metal hydroxide clay than in the filtration of a hydrophilic metal
hydroxide clay, since the hydrophobic clay absorbs less water and
thus can be filtered more quickly.
[0199] As the amorphous hydroxide clay becomes increasingly more
dense with successive reconstitution, more agitation may be
required for sufficient removal of chloride ions. Ammonium ions
present in the mixture have a strong affinity for the chloride
ions, and facilitate removal of chloride from the metal chlorides
to allow formation of metal hydroxides. If the suspended particles
are not reduced in size enough, for example, through wetting and
agitation, the chloride ions may not be removed sufficiently. In
some cases, aqueous ammonium ions, as well as one or more
additives, fillers, etc. described herein, are added during
reconsititution (e.g., to the reconstitution water) as a way of
introduction to the suspension. Ammonium ions from the ion exchange
resin may also enter the suspension.
[0200] After the first filtration, the majority of the amorphous
metal hydroxides are retained in the clay from a filter (e.g., a
multi-layer filter). The clay is a translucent, glassy, opalescent
gel with a slight green tint, and the filtrate, which includes
chloride and ammonium ions, is clear. The filter can be, for
example, a 0.75 micron (GF/F) or 1 micron or 20 micron Whatman
Grade GF/B Glass Microfiber Filter (Whatman plc, UK). Silicon
hydroxide is retained in the gelatinous clay.
[0201] After a third filtration or decantation, chloride ion
concentration is between about 100 and 20.0 ppm, and pH is between
about 8.0 and 8.5, between about 8.0 and 11.5, or greater than
11.5. The gelatinous clay and the filtrate can be visually
inspected to assess, chloride ion removal. A clear filtrate
indicates the presence of an undesirably high amount of chloride
ion, while cloudiness indicates that the chloride ion is being
appropriately decimated.
[0202] After a fourth filtration or decantation, which may be the
final filtration or decantation, the chloride ion concentration
following reconstitution is lowered to about 10 to about 1100 ppm
or about 10 to about 20 ppm, and a pH of the solution is between
about 8.5 and about 9.5 (e.g., about 8.8), or between about 8.5 and
about 11.5. In some cases, one or more additional flirtations or
decantations may be required to lower the chloride ion
concentration to an acceptable level. One or more of a variety of
ion exchange resins, can be added based upon the reconstituted clay
solids from the final filtration in incremental amounts over a
period of about 30-40 minutes to 2.5 hrs to achieve a chloride ion
concentration of about 2 ppm or lower, and a pH of about 7.0 to
about 8.0, or about 7.0 to about 11.5. As the chloride ions are
removed, in contrast to the hydrophilic vehicle systems, ammonium
ions are inhibited from entering the colloidal suspension. Sulfonic
acid from the ion exchange resin can enter the suspension and lower
the pH. Factors such as chloride ion concentration can be used to
determine how much ion exchange resin is needed and how long is
needed to effect substantially complete removal of the chloride
ions. If chloride ions remain after the filtration and ion exchange
process due to, for example, insufficient filtration and or
molecular interference from contamination sources, steric
stabilization required to achieve the stable vehicle system may not
be achieved. Desired chemical and physical attributes such as
hydrophobicity, film formation, binder capabilities, flexibility,
stability, and durability can be realized when the chloride ion
concentration is reduced to about 2 ppm or less, more preferably
about 1 ppm or less, and the pH of the suspension is in a range
from about 8.3 to about 9.3 (e.g., about 8.8 to about 9.2) or from
about 8.3 to about 11.5.
[0203] Chloride ion removal must be substantial while obtaining the
desired pH prior to peroxide addition to the metal hydroxide
reconstituted colloidal suspension. The peroxide is added along
with cooling of the colloidal mixture to below 10.degree. C. About
30.+-.20% (e.g., about 25-35 wt % or about 3.0-33 wt %) peroxide,
based on colloidal solids, is added to the cooled colloidal clay
suspension, causing a decrease in pH of the mixture to about 4 or
below or to about 2 or below. This metal hydroxide reacts with the
peroxide at a reduced temperature, effectively controlling the rate
of the exothermic reaction. If the suspension is not cooled
sufficiently, the particles may fall out of solution. In some
cases, homolytic cleavage of the peroxide occurs. An excess of
peroxide may result in an overly yellow appearance to the film. Any
instability will enhance propensity for precipitation and settling
put of solution. Insufficient peroxide will leave non-reacted
hydroxyl groups on the metal (e.g., silicon, titanium, zirconium)
in the clay and remain re-dispersed in the colloidal suspension,
resulting in reduced film and binding capabilities and thus
contributing to instability. Instability may also be caused by
disadvantageous variations in composition that lead to
precipitation of the colloidal suspension.
[0204] The reaction of metal hydroxide with peroxide may be shown
as:
M(OH).sub.4+3H.sub.2O.sub.2+4NH.sub.4.sup.+(aq).fwdarw.M(OO).sub.4.sup.+-
+5H.sub.2+3O.sub.2+4NH.sub.4.sup.+.
FIG. 6 depicts a model of silicon peroxide formed in this reaction
and stabilized in solution, with ammonium ions proximate the
peroxide groups. Hydrogen bonding with water in the aqueous
solution is thought to stabilize the arrangement of the silicon
peroxide and ammonium ions. After addition of peroxide and cooling
(e.g., for about 24 hours), the mixture, with a pH between about 5
and about 6 (e.g., about 5.6), is brought to room temperature. The
pH rises and stabilizes between about 6.5 and about 7.5 (e.g.,
between about 7.0 and about 7.3) or between about 6.5 and about
11.5. The mixture may be filtered through a GF/B (1 micron filter)
into a flask. After about 50-80% of mixture has been filtered, a
silaceous mesoporous nanogelatinous membrane is formed on the top
of the filter. A secondary reaction occurs in the filtrate as
peroxo groups are stabilized on the metal by ammonium ions,
evidenced by evolution of gas bubbles (e.g., hydrogen and oxygen
gas) from the filtrate.
[0205] The mesoporous gelatinous membrane allows sub-nanometer- to
nanometer-sized particles through the gel, and a stable suspension
of sub-nanometer- and nanometer-sized particles is formed at a pH
in a range from about 7.3 to about 7.6, or from about 7.3 to about
11.5. These nanoparticles are sterically stabilized and may be
thought of as a type of ionic salt in a nearly neutral aqueous
phase solution. These ions are further stabilized by hydrogen
bonding interactions. The metal peroxides are characterized by a
high zeta potential. The siliceous nanogelatinous membrane formed
as a side reaction in the filtrand exhibits mesoporosity attributes
(pore sizes between about 2 nm and about 50 nm or between about 2
nm n and about 300 nm) that allow the nanoparticles of the metal
peroxides to stabilize in the aqueous phase. As these stabilized
nanoparticles are applied on substrates, hydrolysis and
condensation reactions result in polymeric film formation. The gel,
a nanocomposite of hybrid metal oxides, can be reconstituted and
re-filtered to yield more of the vehicle system or for use in a
variety of other applications, such as heterogeneous catalyst
supports.
[0206] Metal peroxide aggregates of nanoparticles in the clear
metal peroxide solution (light transmission up to about 99.9%)
appear to have a size distribution of aggregates ranging from about
10 nm or less to about 15 nm. Solids content of the solution ranges
from about 0.1% to 1%. FIG. 7 (not to scale) depicts metal peroxide
aggregates in solution, and the submesoporous interactions that are
believed to be present. The ammonium-stabilized metal peroxides 700
are thought to be on the order of a few tenths of nanometers. These
stabilized metal peroxides aggregate to form particles on the order
of nanometers. The particles can aggregate in swaths 702, which may
interact, with other swaths of particles in solution. The swaths
may be on the order of tens of nanometers long. When the solution
is applied to a substrate, hydrolysis and condensation reactions
result in a glassy, polymeric film bound to the surface of the
substrate. These films have a thickness ranging from less than 1 nm
to about 5 nm, or in some cases from about 1 nm to about 10 nm,
indicating that the metal peroxide aggregates are loosely
bound.
[0207] Metal salts added in steps 102 or 104 can be selected to
enhance the process of forming a vehicle system, to enhance the
resulting vehicle system, or both. For example, a
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] vehicle system can include about 80
wt % SiO.sub.x, about 15 wt % ZrO.sub.z, and about 5 wt %
TiO.sub.y. During step 102, ZrCl.sub.4 reacts with concentrated HCl
to form ZrOCl.sub.4. This exothermic reaction increases the
solubility of the SiO.sub.x in a [SiO.sub.x:ZrO.sub.z:TiO.sub.y]
formulation relative to the solubility of SiO.sub.x in a
[SiO.sub.x:TiO.sub.y] formulation. Additionally, zirconium oxide in
the polymeric film formed by a [SiO.sub.x:ZrO.sub.z:TiO.sub.y]
vehicle system yields harder and more crack-resistant films.
[0208] [SiO.sub.x:ZrO.sub.z:TiO.sub.y] formulations are scratch
resistant, transparent optical coatings that can be used in a
variety of applications, such as catalyst supports, for which
strength, adhesion, chemical and physical (e.g., thermal)
durability are desired. As catalyst supports, the vehicle systems
can be, applied as a protective layer to organic substrates that
would otherwise be damaged by photocatalytic [TiO.sub.y:SiO.sub.x]
compositions. In some embodiments, a photocatalytic coating is
applied over a protective [SiO.sub.x:ZrO.sub.z:TiO.sub.y] coating.
The [SiO.sub.x:ZrO.sub.z:TiO.sub.y] coating can also enhance
adhesion strength of the photocatalytic coating. In some cases, a
[TiO.sub.y:SiO.sub.x] formulation is dispersed in a
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] formulation to achieve a desired
distribution of metal oxides. In other cases, a protective
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] coating is applied over a
photocatalytic [TiO.sub.y:SiO.sub.x].
[0209] In some embodiments, a silaceous, nanogelatinous membrane
with a composition of [SiO.sub.x:TiO.sub.y] or
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] can be reconstituted to form a
vehicle system with a solids content between, about 0.1 and 0.25 wt
% or between about 0.1 and 1 wt % of the total system. The vehicle
system can be spray dried as a heterogeneous mesoporous silica
pigment. The surface area of the dispersed nanoparticles is thought
to be several hundred square meters per gram. The applied
composition forms a thin, durable film of [SiO.sub.x:TiO.sub.y]
"glass." Utilizing a foam brush, a 25 micron wet film application
of a composition with a solids content of about 0.25% after
filtration yields a firm build of about 63.+-.6 nm. Similarly,
utilizing a foam brush, a 25 micron wet film application of a
composition with a solids content of about 0.1% after filtration
yields a film build of about 25 mm.
[0210] [SiO.sub.x:ZrO.sub.z:TiO.sub.y] vehicle systems can be used
to form high .kappa. dielectrics for use in semiconductor chips. In
some embodiments, the weight ratios of
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] are formulated to obtain a desired
dielectric constant while achieving a film thickness targeted by
the industry of about 4-6 nm, or even 1 nm or less for future
advances. Percentage composition of the vehicle system can be
tailored to achieve a high .kappa. dielectric by adding a selected
amount of silicon (dielectric constant of silicon dioxide=2 to
3.8), zirconium (dielectric constant of zirconium oxide=12.5),
titanium (dielectric constant of titanium oxide=110), or any
combination thereof. Thus, hybrid metal oxides described herein can
easily provide an appropriately thin film with a dielectric
constant adjustably higher than that of pure silicon dioxide.
Moreover, these layers can be formed by simple (e.g, spray or
brush) application of purely inorganic, aqueous film formers, and
film formation can occur by drying at ambient temperature,
eliminating the need for organometallics and volatile hazardous air
pollutant solvents. Additionally, problems associated with carbon
soot and electrically charged gate leakage are avoided.
[0211] The high water content (at least about 98 wt %) and the low
solids content (less than about 2%, or between about 0.1% and 1%)
of the vehicle systems described herein make them suitable for
coating transparent substrates. With an effective percentage of
anatase titanium oxide, [SiO.sub.x:TiO.sub.y] systems can be made
increasingly photocatalytic. These systems can bond to transparent
substrates such as glass and other substrates with hydroxide groups
on the surface. Since the silicon oxide has a lower refractive
index than the titanium oxide, a higher percentage of silicon oxide
allows the light to remain in the film longer, resulting in
improved photocatalytic efficacy of the coating. Thus, the
[SiO.sub.x:TiO.sub.y] system can form a catalytic support matrix
for a variety of catalytic reactions that benefit from high surface
areas. In some embodiments, [SiO.sub.x:TiO.sub.y] formulations are
applied over elastomeric, thermoset, or thermoplastic substrates
and coated with a photocatalytic coating to protect organic
polymeric substrates from photocatalytic degradation.
[0212] For a corrosion resistant film to be applied over a metal
substrate, a [SiO.sub.x:TiO.sub.y] composition can include
SiO.sub.x:TiO.sub.y in a weight ratio of about 9:1 to about
9.99:0.01. In some cases, the vehicle system includes 100 wt %
SiO.sub.x. Hybrid [SiO.sub.x:ZrO.sub.z:TiO.sub.y] formulations are
also suitable for corrosion resistant coatings and can protect a
substrate with hard, substantially impermeable, scratch-resistant
film. Free radical degradation through exterior exposure is
inhibited at the interface between the coating and the metal. These
inorganic, polymeric coatings can protect a variety of metal
substrates from anodic and cathodic electrochemical transport, thus
inhibiting the electrochemical circuit required for corrosion,
including galvanic corrosion, concentration cell corrosion, oxygen
concentration cell corrosion, filiform corrosion, metal ion
concentration cell corrosion, active/passive corrosion cells,
intergranular corrosion, exfoliation corrosion, and metallic
mercury corrosion.
[0213] The small particles in vehicle systems described herein
yield thin, flexible glass coatings that can be used to seal
exposed surfaces at the nanometer to mesoporous and macro film
build levels, and thus cover substantially all exposed areas on a
substrate. In some cases, organic monomers can be polymerized
through hydrolysis and condensation reactions to form a polymer
upon subsequent application of thin films. The incorporation of,
for example, urethane or polyester functionality, together with
silanes, can provide flexibility. More than one coating of the same
or different composition and thickness can be applied to a surface
to achieve desired results.
[0214] In some embodiments, a low percentage of photocatalytic
anatase particles can be essentially locked in an inorganic glass
film or matrix formed by a [SiO.sub.x:TiO.sub.y] vehicle system.
These vehicle systems include, for example, at least about 90 wt %
or at least about 99.9 wt % of SiO.sub.x. In one embodiment,
vehicle systems with about 98 wt % SiO.sub.x and about 2 wt %
TiO.sub.y yield glass films with a thickness of about 1 nm to about
5 nm. In these hydrophobic embodiments, a low level of the anatase
particles can function effectively as a UV absorber without
degrading the coating.
[0215] In certain embodiments, a [SiO.sub.x:ZrO.sub.z:TiO.sub.y]
vehicle system includes addition of dipodal silanes such as, but
not limited to, bis(trimethoxysilyl)methane or bis(triethoxysilyl
ethane silanes. The affinity of silane is greater for a vehicle
system that is predominantly SiO.sub.x than for a vehicle system
that is predominantly TiO.sub.y. Thus, incorporating
bis(trimethoxysilyl)methane or (triethoxysilyl ethane into a
[SiO.sub.x:ZrO.sub.z:TiO.sub.y] vehicle system yields a coating
with hardness, adhesion, and scratch resistance superior to that of
coatings formed from a [TiO.sub.y:SiO.sub.x] vehicle system with
the same additive.
Example 1
[0216] SiCl.sub.4 was incorporated to an aqueous mixture of
titanium-based solution, including an acid and another metal
chloride. A metal organic was incorporated into the vehicle system
through the process depicted in FIG. 1, including neutralization of
the acidic mixture with an ammonia-based solution, after which the
solution had the appearance of a water-glass or a liquid silica.
After filtration, reconstitution of the metal hydroxide, and
addition of a peroxide-based solution, bis(triethoxysilyl)ethane
was added to the amorphous metal peroxide solution.
Bis(triethoxysilyl)ethane is a dipodal silane with the ability to
form six bonds to a substrate. Once these bonds are formed, the
resistance to hydrolysis is estimated to be about 100,000 times
greater than that of conventional coupling agents with the ability
to form only three bonds to a substrate, or about 75,000 times
greater than a silane (such as tetraethoxysilane) able to form 4
bonds to a substrate.
[0217] The solution was boiled under pressure greater than
atmospheric pressure. Continued boiling under pressure to increase
the nanocrystalline metal oxide ratio resulted in an adhesive,
transparent, photocatalytic film believed to provide corrosion
inhibition when bonded to untreated steel substrates. The resulting
PMHNC coating is believed to be a hybrid crystal of silicon,
anatase, and zinc oxide, thought to include linear species such as
Si--O--Ti--O--Ti--O--Ti--O--Zn--O.
Example 2
[0218] Non-porous ceramic tiles were coated with Composition A made
as described herein with respect to the process in FIG. 1, with
relative, Si:Ti:Zr:Sn oxide percentages in the hybrid metal oxide
of 0.63:90.68:3.31:4.48.
[0219] Two tiles were coated with Composition A and two tiles
coated with a competing product were allowed to cure at ambient
temperature for 24 hrs. 5 drops of deionized water:methylene blue,
solution (water:methylene blue ratio of 1000:1) were deposited with
a 3 mL pipette on one tile with a Composition A coating and one
tile with the competing product coating. The drops were spread in a
circle with a diameter of 2 cm. Tiles without methylene blue (one
tile with a coating formed from Composition A and one tile with a
coating formed from the competing product) were kept in the dark
(dark control tiles).
[0220] The tiles with methylene blue drops were exposed to the
south Florida sun during the day. Overnight, the tiles were placed
33 cm from UV lamps (F15T8BL 15W T8 18'' BLACK LIGHT LITE F15W/BL
emitting 365 nm manufactured by General Electric). Color readings
of the methylene blue spots on each of the four tiles were taken at
8 hr intervals using an X-Rite 918 Tristimulus. Reflection
Colorimeter 0.degree./45.degree.. Delta E of the methylene blue
spots on the dark control tiles and the light-exposed tiles were
recorded. As the stains on the two light-exposed treated tiles were
remediated, the stained areas became lighter in total color and
thus closer to the color of the dark control tiles.
[0221] FIG. 8 shows % stain remediation of the dark control (no
stains) and light-exposed tiles coated with Composition A and the
competing product. The light-exposed tile coated with Composition A
(plot 800) exhibited dramatic and surprising increasing
photocatalytic efficacy as compared to the light-exposed tile
coated with the competing product (plot 802). The dark controls are
indistinguishable (plot 806). After approximately 100 hrs exposure,
the tile coated with Composition A remediated the methylene blue
with a 48% more effective photocatalytic efficacy than the tile
coated with the competing product.
[0222] A number of embodiments of the invention have been
described. Nevertheless, it will be understood that various
modifications may be made without departing from the spirit and
scope of the invention. Accordingly, other embodiments are within
the scope of the following claims.
* * * * *