U.S. patent application number 11/101760 was filed with the patent office on 2005-08-25 for forming thin films on substrates using a porous carrier.
This patent application is currently assigned to Innovation Chemical Technologies, Ltd.. Invention is credited to Arora, Pramod K..
Application Number | 20050186412 11/101760 |
Document ID | / |
Family ID | 26767762 |
Filed Date | 2005-08-25 |
United States Patent
Application |
20050186412 |
Kind Code |
A1 |
Arora, Pramod K. |
August 25, 2005 |
Forming thin films on substrates using a porous carrier
Abstract
The invention relates to a composite containing a porous carrier
and an amphiphilic material. The composite may be employed in
methods and systems for forming thin films on substrates.
Inventors: |
Arora, Pramod K.; (North
Royalton, OH) |
Correspondence
Address: |
AMIN & TUROCY, LLP
1900 EAST 9TH STREET, NATIONAL CITY CENTER
24TH FLOOR,
CLEVELAND
OH
44114
US
|
Assignee: |
Innovation Chemical Technologies,
Ltd.
|
Family ID: |
26767762 |
Appl. No.: |
11/101760 |
Filed: |
April 8, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11101760 |
Apr 8, 2005 |
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10082712 |
Feb 25, 2002 |
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6881445 |
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60350096 |
Oct 29, 2001 |
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Current U.S.
Class: |
428/312.8 ;
427/11 |
Current CPC
Class: |
B05D 1/60 20130101; C03C
25/22 20130101; C03C 17/001 20130101; C23C 14/243 20130101; C23C
14/12 20130101; Y10T 428/24997 20150401 |
Class at
Publication: |
428/312.8 ;
427/011 |
International
Class: |
B32B 009/04; B05D
001/00 |
Claims
What is claimed is:
1. A method of forming a thin film on a substrate, comprising:
providing the substrate in a chamber; inserting a composite
comprising a metallic porous carrier and an amphiphilic material
into the chamber, wherein the amphiphilic material is represented
by Formula I: R.sub.mSiZ.sub.n (I) where each R is individually
fluorinated alkyl or fluorinated alkyl ether containing from about
1 to about 30 carbon atoms; each Z is individually one of hydrogen,
halogens, hydroxy, alkoxy and acetoxy; and m is from about 1 to
about 3, n is from about 1 to about 3, and m+n equal 4; in the
chamber, setting at least one of a temperature of the composite
from about 20 to about 400.degree. C. and a pressure from about
0.000001 to about 760 torr to induce vaporization of the
amphiphilic material; and recovering the substrate having the thin
film thereon.
2. The method of claim 1, wherein the substrate comprises at least
one of a glass, a glass having an antireflection coating thereon,
silica, germanium oxide, a ceramic, porcelain, fiberglass, a metal,
a thermoset, and a thermoplastic.
3. The method of claim 1, wherein the metallic porous carrier
comprises pores having an average pore size from about 1 micron to
about 1,000 microns.
4. The method of claim 1, wherein the metallic porous carrier has a
porosity so that it absorbs from about 0.001 g to about 5 g of
amphiphilic material per cm.sup.3 of metallic porous carrier.
5. The method of claim 1, wherein the metallic porous carrier
comprises at least one of aluminum, brass, bronze, chromium,
copper, gold, iron, nickel, palladium, platinum, silver, stainless
steel, tin, titanium, tungsten, zinc, and zirconium.
6. The method of claim 1, after setting at least one of the
temperature and the pressure, keeping the substrate in the chamber
for a time from about 10 seconds to about 24 hours.
7. The method of claim 1, wherein where each R is fluorinated alkyl
ether containing from about 1 to about 30 carbon atoms.
8. The method of claim 1, wherein the pressure is set prior to
setting the temperature.
9. The method of claim 1, wherein the temperature is set from about
40 to about 350.degree. C. and the pressure is set from about
0.00001 to about 200 torr.
10. The method of claim 1, wherein the thin film is formed at a
rate of about 0.01 nm/sec or more and about 1 nm/sec or less.
11. The method of claim 1, wherein the thin film has a thickness
from about 1 nm to about 250 nm.
12. A system for forming a thin film, comprising: a film forming
chamber in communication with at least one of a heat source and a
vacuum system; a composite comprising a metallic porous carrier and
an amphiphilic material positionable within the film forming
chamber, the amphiphilic material comprising at least one of a
polyhedral oligomeric silsesquioxane and a compound represented by
Formula I: R.sub.mSiZ.sub.n (I) where each R is individually
fluorinated alkyl or fluorinated alkyl ether containing from about
1 to about 30 carbon atoms; each Z is individually one of hydrogen,
halogens, hydroxy, alkoxy and acetoxy; and m is from about 1 to
about 3, n is from about 1 to about 3, and m+n equal 4; and a
substrate on which the thin film is formed positionable within the
film forming chamber.
13. The system of claim 12, wherein the film forming chamber is in
communication with a heat source and a vacuum system.
14. The system of claim 12, wherein the metallic porous carrier
comprises pores having an average pore size from about 5 microns to
about 500 microns.
15. The system of claim 12, wherein the composite comprises from
about 0.01 g to about 2 g of the amphiphilic material per cm.sup.3
of metallic porous carrier.
16. The system of claim 12, wherein the composite further comprises
at least one of a non-polar organic solvent, a film forming
catalyst, and a quencher.
17. A film forming composite, comprising: a metallic porous carrier
comprising pores having an average pore size from about 1 micron to
about 1,000 microns; and an amphiphilic material, the amphiphilic
material comprising at least one of a polyhedral oligomeric
silsesquioxane and a compound represented by Formula I:
R.sub.mSiZ.sub.n (I) where each R is individually fluorinated alkyl
or fluorinated alkyl ether containing from about 1 to about 30
carbon atoms; each Z is individually one of hydrogen, halogens,
hydroxy, alkoxy and acetoxy; and m is from about 1 to about 3, n is
from about 1 to about 3, and m+n equal 4, wherein the metallic
porous carrier has a porosity so that it absorbs from about 0.001 g
to about 5 g of amphiphilic material per cm.sup.3 of metallic
porous carrier.
18. The film forming composite of claims 17, wherein the metallic
porous carrier comprises at least one of aluminum, brass, bronze,
chromium, copper, gold, iron, nickel, palladium, platinum, silver,
stainless steel, tin, titanium, tungsten, zinc, and zirconium.
19. The film forming composite of claims 17, wherein the metallic
porous carrier comprises pores having an average pore size from
about 5 microns to about 500 microns and the porous carrier has a
porosity so that it absorbs from about 0.01 g to about 1 g of
amphiphilic material per cm.sup.3 of metallic porous carrier.
20. The film forming composite of claims 17, wherein the composite
has one of a cylindrical shape, a spherical shape, an oval shape, a
tablet shape, a disc shape, a plug shape, a pellet shape, a cubical
shape, a rectangular shape, and a conical shape.
21-23. (canceled)
Description
RELATED APPLICATIONS
[0001] This application claims priority to provisional application
Ser. No. 60/350,096 filed Oct. 29, 2001, the contents of which are
incorporated herein.
FIELD OF THE INVENTION
[0002] The present invention generally relates to thin films. In
particular, the present invention relates to forming a high quality
thin film on substrate using a porous carrier.
BACKGROUND OF THE INVENTION
[0003] Polymerizable amphiphilic molecules and hydrolysable alkyl
silanes are employed to form thin films on various surfaces. Thin
films have numerous and diverse useful purposes. For example, a
thin film may be formed on a lens for scratch resistance or on a
metal for corrosion protection.
[0004] It is difficult to form a thin film of amphiphilic molecules
directly on a lens, so a silicon dioxide layer is initially formed
on the lens in an anhydrous environment in a first chamber. The
silica coated lens is then transferred to a second chamber for
deposition of the film of amphiphilic molecules. During the
transfer, the silica coated lens is exposed to water vapor in the
air which hydrolyzes the surface and permits subsequent strong
adhesion between the amphiphilic molecules and the lens. Forming
the amphiphilic thin film in the same chamber as the silica layer
leads to corrosion of the interior of the chamber, the
contamination of the chamber preventing repeated use of the chamber
for the two step process without thorough cleaning, and the
undesirable formation of a messy, difficult to clean film on the
interior of the chamber. Nevertheless, in some instances, the
requirement of two chambers can be cumbersome.
[0005] When forming a thin film on a substrate, a film forming
material is typically dissolved in a solvent. The solvent/film
forming material mixture is then contacted with the substrate. One
problem with forming a thin film in this manner is that the solvent
is typically toxic, and may be hazardous due to flammability. In
other words, the use of solvents that can dissolve film forming
materials may undesirably raise serious health and environmental
concerns. Disposal of the solvents is a serious environmental
concern particularly in the case of oil base and halocarbon
solvents.
[0006] Furthermore, the use of such solvents leads to the
generation of hydrogen chloride gas as a by-product, which creates
additional serious health hazards, unless a neutralizer trap is
used and properly disposed according to EPA and OSHA regulations.
Proper use and disposal is very difficult in a working environment,
especially since an operator must track such use. Hence, each
operator and lab may require having toxic gas monitors or employ
the use of vapor masks, which are uncomfortable to operator.
[0007] One recent development in the field of thin film formation
is the use of an ampuole to deliver a film forming material to a
substrate. Using a vapor phase coating process, an ampuole
containing a film forming material is placed in a vacuum chamber
with the substrate. After a vacuum is established, the ampuole
breaks releasing the film forming material which vaporizes and
proceeds to form a film on the substrate. The ampuole is an easy to
handle, convenient vehicle to charge the chamber with a film
forming material. However, there are several concerns when using an
ampuole in this manner.
[0008] First, when the ampuole breaks releasing the film forming
material, broken glass may damage the substrate. Due to pressure
differences between the inside of the ampuole and the vacuum
chamber, the ampuole breaks with undesirably high force, projecting
glass pieces throughout the chamber. A related problem is that the
film forming material then undesirably forms a film over the broken
glass pieces in addition to the substrate, thereby lowering the
amount of film forming material destined for the substrate.
[0009] Second, when the ampuole breaks with high force, the film
forming material tends to spurt out, leading to a non-uniform film
on the substrate. The inability to control the release of the film
forming material raises the need to inspection and often cleaning
of coated substrates.
SUMMARY OF THE INVENTION
[0010] One aspect of the invention relates to a composite
containing a porous carrier and an amphiphilic material. The
amphiphilic material is useful for forming thin films on
substrates. The composite may thus be employed in methods and
systems for forming thin films on substrates. Since the porous
carrier is used to deliver the amphiphilic material to the chamber,
damage to substrates is mitigated while uniform distribution of
amphiphilic material vapor is facilitated. Moreover, the porous
carrier mitigates splashing as the amphiphilic material is
vaporized. Less splashing leads to less waste.
[0011] As a result, the thin film formed on the substrate using the
composite of a porous carrier impregnated with the amphiphilic
molecules is continuous in nature. Pinholes and other film defects
commonly observed in conventionally made thin films are minimized
and/or eliminated.
[0012] Another aspect of the invention relates to a composite
containing a porous carrier and a polyhedral oligomeric
silsesquioxane amphiphilic material. When using the polyhedral
oligomeric silsesquioxane amphiphilic material, it is unnecessary
to expose the substrate to water vapor in the event a silica (or
other metal oxide type coating) coating is employed to improve
adhesion. As a result, the formation of silica and the amphiphilic
thin film can be conducted in one chamber, simplifying the coating
process.
BRIEF SUMMARY OF THE DRAWINGS
[0013] FIG. 1 is an illustration of a composite for forming thin
films in accordance with one aspect of the present invention.
[0014] FIG. 2 is an illustration of a composite for forming thin
films in accordance with another aspect of the present
invention.
[0015] FIG. 3 is an illustration of a composite for forming thin
films in accordance with yet another aspect of the present
invention.
[0016] FIG. 4 is a schematic view of a system for forming thin
films in accordance with one aspect of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] Using a composite containing a porous carrier and amphiphlic
material, uniform and continuous thin films can be efficiently
formed on substrates without damaging the substrates. The porous
carrier, akin to a metal sponge in certain instances, constitutes
an advantageous vehicle for facilitating the vapor deposition of a
thin film made of an amphiphlic material.
[0018] Amphiphilic molecules have the intrisic ability to self
assemble and/or self-polymerize in a thin film. Amphiphilic
molecules typically have head and tail groups (tail being a
nonreactive, non-polar group and head being reactive, polar group).
Amphiphilic molecules generally include polymerizable amphiphilic
molecules, hydrolyzable alkyl silanes, hydrolyzable perhaloalkyl
silanes, chlorosilanes, polysiloxanes, alkyl silazanes,
perfluoroalkyl silazanes, disilazanes, and silsesquioxanes.
[0019] The polar group or moiety of the amphiphile can be a
carboxylic acid, alcohol, thiol, primary, secondary and tertiary
amine, cyanide, silane derivative, phosphonate, and sulfonate and
the like. The non-polar group or moiety mainly includes alkyl
groups, per fluorinated alkyl groups, alkyl ether groups, and
per-fluorinated alkyl ether groups. These non-polar groups may
include diacetylene, vinyl-unsaturated or fused linear or branched
aromatic rings.
[0020] In one embodiment, the amphiphilic molecule is represented
by Formula I:
R.sub.mSiZ.sub.n (I)
[0021] where each R is individually an alkyl, fluorinated alkyl,
alkyl ether or fluorinated alkyl ether containing from about 1 to
about 30 carbon atoms, substituted silane, or siloxane; each Z is
individually one of halogens, hydroxy, alkoxy and acetoxy; and m is
from about 1 to about 3, n is from about 1 to about 3, and m+n
equal 4. In another embodiment, R is an alkyl, fluorinated alkyl,
an alkyl ether or a fluorinated alkyl ether containing from about 6
to about 20 carbon atoms. The alkyl group may contain the
diacetylene, vinyl-unsaturated, single aromatic and fused linear or
branched aromatic rings.
[0022] In another embodiment, the amphiphilic molecule is
represented by Formula II:
R.sub.mSH.sub.n (II)
[0023] where R is an alkyl, fluorinated alkyl, an alkyl ether or a
fluorinated alkyl ether containing from about 1 to about 30 carbon
atoms; S is sulfur; H is hydrogen; m is from about 1 to about 2 and
n is from 0 to 1. In another embodiment, R is an alkyl, fluorinated
alkyl, an alkyl ether or a fluorinated alkyl ether containing from
about 6 to about 20 carbon atoms. The alkyl chain may contain
diacetylene, vinyl, single aromatics, or fused linear or branched
aromatic moieties.
[0024] In yet another embodiment, the amphiphilic molecule is
represented by RY, where R is an alkyl, fluorinated alkyl, an alkyl
ether or a fluorinated alkyl ether containing from about 1 to about
30 carbon atoms and Y is one of the following functional groups:
--COOH, --SO.sub.3H, --PO.sub.3, --OH, and --NH.sub.2. In another
embodiment, R is an alkyl, fluorinated alkyl, an alkyl ether or a
fluorinated alkyl ether containing from about 6 to about 20 carbon
atoms. The alkyl chain may contain diacetylene, vinyl-unsaturated,
single aromatic, or fused linear or branched aromatic moieties.
[0025] In still yet another embodiment, the amphiphilic molecule
may include one or more of the following Formulae (III) and
(IV):
CF.sub.3(CF.sub.2).sub.7CH.sub.2CH.sub.2--Si(CH.sub.3).sub.2Cl
(III)
CF.sub.3(CF.sub.2).sub.7CH.sub.2CH.sub.2--Si(OEt).sub.3 (IV)
[0026] In another embodiment, the amphiphilic molecule is a
disilazane represented by Formula V:
RSiNSiR (V)
[0027] where R is an alkyl, fluorinated alkyl, an alkyl ether or a
fluorinated alkyl ether containing from about 1 to about 30 carbon
atoms. In another embodiment, R is an alkyl, fluorinated alkyl, an
alkyl ether or a fluorinated alkyl ether containing from about 6 to
about 20 carbon atoms.
[0028] In another embodiment, the amphiphilic molecule is
represented by Formula VI:
R(CH.sub.2CH.sub.2O).sub.qP(O).sub.x(OH).sub.y (VI)
[0029] where R is an alkyl, fluorinated alkyl, an alkyl ether or a
fluorinated alkyl ether containing from about 1 to about 30 carbon
atoms, q is from about 1 to about 10, and x and y are independently
from about 1 to about 4.
[0030] In still yet another embodiment, the amphiphilic molecule is
formed by polymerizing a silicon containing compound, such as
tetraethylorthosilicate (TEOS), tetramethoxysilane, and/or
tetraethoxysilane.
[0031] Amphiphilic molecules (and in some instances compositions
containing amphiphilic molecules) are described in U.S. Pat. Nos.
6,238,781; 6,206,191; 6,183,872; 6,171,652; 6,166,855 (overcoat
layer); 5,897,918; 5,851,674; 5,822,170; 5,800,918; 5,776,603;
5,766,698; 5,759,618; 5,645,939; 5,552,476; and 5,081,192; Hoffmann
et al., and "Vapor Phase Self-Assembly of Fluorinated Monlayers on
Silicon and German Oxide," Langmuir, 13, 1877-1880, 1997; which are
hereby incorporated by reference for their teachings of amphiphilic
materials.
[0032] Specific examples of amphiphilic molecules and compounds
that can be hydrolyzed into amphiphilic materials include
octadecyltrichlorosilane- ; octyltrichlorosilane;
heptadecafluoro-1,1,2,2-tetrahydrodecyl trichlorosilane available
from Shin Etsu under the trade designation KA-7803; hexadecyl
trimethoxysilane available from Degussa under the trade designation
Dynasylan 9116; tridecafluorooctyl triethoxysilane available from
Degussa under the trade designation Dynasylan F 8261;
methyltrimethoxysilane available from Degussa under the trade
designation Dynasylan MTMS; methyltriethoxysilane available from
Degussa under the trade designation Dynasylan MTES;
propyltrimethoxysilane available from Degussa under the trade
designation Dynasylan PTMO; propyltriethoxysilane available from
Degussa under the trade designation Dynasylan PTEO;
butyltrimethoxysilane available from Degussa under the trade
designation Dynasylan IBTMO; butyltriethoxysilane available from
Degussa under the trade designation Dynasylan BTEO;
octyltriethoxysilane available from Degussa under the trade
designation Dynasylan OCTEO; fluoroalkylsilane in ethanol available
from Degussa under Dynasylan 8262; fluoroalkylsilane-formulation in
isopropanol available from Degussa under Dynasylan F 8263; modified
fluoroalkyl-siloxane available from Degussa under Dynasylan.RTM. F
8800; and a water-based modified fluoroalkyl-siloxane available
from Degussa under Dynasylan F 8810. Additional examples of
amphiphilic molecules and compounds that can be hydrolyzed into
amphiphilic materials include fluorocarbon compounds and
hydrolyzates thereof under the trade designation Optool DSX
available from Daikin Industries, Ltd.; silanes under the trade
designations KA-1003 (vinyltrichloro silane), KBM-1003
(vinyltrimethoxy silane), KBE-1003 (vinyltriethoxy silane), KBM-703
(chloropropyltrimethoxy silane), X-12-817H, X-71-101, X-24-7890,
KP801M, KA-12 (methyldichloro silane), KA-13 (methyltrichloro
silane), KA-22 (dimethyldichloro silane), KA-31 (trimethylchloro
silane), KA-103 (phenyltrichloro silane), KA-202 (diphenyldichloro
silane), KA-7103 (trifluoropropyl trichloro silane), KBM-13
(methyltrimethoxy silane), KBM-22 (dimethyldimethoxy silane),
KBM-103 (phenyltrimethoxy silane), KBM-202SS (diphenyldimethoxy
silane), KBE-13 (methyltriethoxy silane), KBE-22 (dimethyldiethoxy
silane), KBE-103 (phenyltriethoxy silane), KBE-202
(diphenyldiethoxy silane), KBM-3063 (hexyltrimethoxy silane),
KBE-3063 (hexyltriethoxy silane), KBM-3103 (decyltrimethoxy
silane), KBM-7103 (trifluoropropyl trimethoxysilane), KBM-7803
(heptadecafluoro-1,1,2,2-tetrahydrodecyl trimethoxysilane), and
KBE-7803 (heptadecafluoro-1,1,2,2-tetrahydrodecyl triethoxysilane)
available from Shin Etsu.
[0033] Additional specific examples of amphiphilic materials
include C.sub.9F.sub.19C.sub.2H.sub.4Si(OCH.sub.3).sub.3;
(CH.sub.3O).sub.3SiC.su-
b.2H.sub.4C.sub.6F.sub.12C.sub.2H.sub.4Si(OCH.sub.3).sub.3;
C.sub.9F.sub.19C.sub.2H.sub.4Si(NCO).sub.3;
(OCN).sub.3SiC.sub.2H.sub.4Si- (NCO).sub.3; Si(NCO).sub.4;
Si(OCH.sub.3).sub.4; CH.sub.3Si(OCH.sub.3).sub- .3;
CH.sub.3Si(NCO).sub.3; C.sub.8H.sub.17Si(NCO).sub.3;
(CH.sub.3).sub.2Si(NCO).sub.2;
C.sub.8F.sub.17CH.sub.2CH.sub.2Si(NCO).sub- .3;
(OCN).sub.3SiC.sub.2H.sub.4C.sub.6F.sub.12C.sub.2H.sub.4Si(NCO).sub.3;
(CH.sub.3).sub.3SiO--[Si(CH.sub.3).sub.2--O-].sub.n--Si(CH.sub.3).sub.3
(viscosity of 50 centistokes);
(CH.sub.3O).sub.2(CH.sub.3)SiC.sub.2H.sub.-
4C.sub.6F.sub.12C.sub.2H.sub.4Si(CH.sub.3)(OCH.sub.3).sub.2;
C.sub.8F.sub.17CH.sub.2CH.sub.2Si(OCH.sub.3).sub.3;
dimethylpolysiloxane having a viscosity of 50 centistokes (KF96,
manufactured by Shin Etsu); modified diemthylpolysiloxane having a
viscosity of 42 centistokes and having hydroxyl groups at both
terminals (KF6001, manufactured by Shin Etsu); and modified
dimethylpolysiloxane having a viscosity of 50 centistokes and
having carboxyl groups (X-22-3710, manufactured by Shin Etsu).
[0034] In another embodiment, the amphlphilic material contains a
repeating unit of a polyorganosiloxane introduced into a
fluoropolymer. The fluoropolymer having the repeating unit of a
polyorganosiloxane can be obtained by a polymerization reaction of
a fluoromonomer and a polyorganosiloxane having a reactive group as
a terminal group. The reactive group is formed by chemically
binding an ethylenically unsaturated monomer (e.g., acrylic acid,
an ester thereof, methacrylic acid, an ester thereof, vinyl ether,
styrene, a derivative thereof) to the end of the
polyorganosiloxane.
[0035] The fluoropolymer can be obtained by a polymerization
reaction of an ethylenically unsaturated monomer containing
fluorine atom (fluoromonomer). Examples of the fluoromonomers
include fluoroolefins (e.g., fluoroethylene, vinylidene fluoride,
tetrafluoroethylene, hexafluoropropylene,
perfluoro-2,2-dimethyl-1,3-diol), fluoroalkyl esters of acrylic or
methacrylic acid and fluorovinyl ethers. Two or more fluoromonomers
can be used to form a copolymer.
[0036] A copolymer of a fluoromonomer and another monomer can also
be used as the amphiphilic material. Examples of the other monomers
include olefins (e.g., ethylene, propylene, isoprene, vinyl
chloride, vinylidene chloride), acrylic esters (e.g., methyl
acrylate, ethyl acrylate, 2-ethylhexyl acrylate), methacrylic
esters (e.g., methyl methacrylate, ethyl methacrylate, butyl
methacrylate, ethylene glycol dimethacrylate), styrenes (e.g.,
styrene, vinyltoluene, alpha.-methylstyrene), vinyl ethers (e.g.,
methyl vinyl ether), vinyl esters (e.g., vinyl acetate, vinyl
propionate, vinyl cinnamate), acrylamides (e.g.,
N-tert-butylacrylamide, N-cyclohexylacrylamide), methacrylamides
and acrylonitriles.
[0037] Amphiphilic molecules further include the hydrolyzation
products of any of the compounds described above. In particular,
treating any of the above described compounds with an acid or base
yields amphiphilic materials ideally suited for forming thin film
on substrates.
[0038] Amphiphilic molecules specifically include polyhedral
oligomeric silsesquioxanes (POSS), and such compounds are described
in U.S. Patents 6,340,734; 6,284,908; 6,057,042; 5,691,396;
5,589,562; 5,422,223; 5,412,053; J. Am. Chem. Soc.
1992,114,6701-6710; J. Am. Chem. Soc. 1990, 112, 1931-1936; Chem.
Rev. 1995, 95,1409-1430; and Langmuir, 1994, 10, 4367, which are
hereby incorporated by reference. The POSS oligomers/polymers
contain reactive hydroxyl groups. Moreover, the POSS
polymers/oligomers have a relatively rigid, thermally stable
silicon-oxygen framework that contains an oxygen to silicon ratio
of about 1.5. These compounds may be considered as
characteristically intermediate between siloxanes and silica. The
inorganic framework is in turn covered by a
hydrocarbon/fluorocarbon outer layer enabling solubilization and
derivatization of these systems, which impart
hydrophobic/oleophobic properties to the substrate surface in a
manner similar as alkyltrichlorosilanes.
[0039] In one embodiment the POSS polymer contains a compound
represented by Formula (VI):
[R(SiO).sub.x(OH).sub.Y] (VII)
[0040] where R is an alkyl, aromatic, fluorinated alkyl, an alkyl
ether or a fluorinated alkyl ether containing from about 1 to about
30 carbon atoms; x is from about 1 to about 4; and y is from about
1 to about 4. In another embodiment, R is an alkyl, aromatic,
fluorinated alkyl, an alkyl ether or a fluorinated alkyl ether
containing from about 6 to about 20 carbon atoms; x is from about 1
to about 3; and y is from about 1 to about 3. Such a compound can
be made by stirring RSiX.sub.3, such as an alkyl trihalosilane, in
water and permitting it to hydrolyze, using an acid or base (such
as HCl or ammonium hydroxide, respectively) to further hydrolyze
the first hydrolization product.
[0041] Examples of POSS polymers include
poly(p-hydroxybenzylsilsesquioxan- e) (PHBS);
poly(p-hydroxybenzylsilsesquioxane-co-methoxybenzylsilsesquioxa-
ne) (PHB/MBS);
poly(p-hydroxybenzylsilsesquioxane-co-t-butylsilsesquioxane- )
(PHB/BS);
poly(p-hydroxybenzylsilsesquioxane-co-cyclohexylsilsesquioxane- )
(PHB/CHS);
poly(p-hydroxybenzylsilsesquioxane-co-phenylsilsesquioxane)
(PHB/PS);
poly(p-hydroxybenzylsilsesquioxane-co-bicycloheptylsilsesquioxa-
ne) (PHB/BHS); poly(p-hydroxyphenylethylsilsesquioxane) (PHPES);
poly(p-hydroxyphenylethylsilsesquioxane-co-p-hydroxy-.alpha.-methylbenzyl-
s ilsesquioxane) (PHPE/HMBS);
poly(p-hydroxyphenylethylsilsesquioxane-co-m-
ethoxybenzylsilsesquioxane) (PHPE/MBS);
poly(p-hydroxyphenylethylsilsesqui- oxane-co-t-butylsilsesquioxane)
(PHPE/BS); poly(p-hydroxyphenylethylsilses-
quioxane-co-cyclohexylsilsesquioxane) (PHPE/CHS);
poly(p-hydroxyphenylethy- lsilsesquioxane-co-phenylsilsesquioxane)
(PHPE/PS);
poly(p-hydroxyphenylethylsilsesquioxane-co-bicycloheptylsilsesquioxane)
(PHPE/BHS); poly(p-hydroxy-a-methylbenzylsilsesquioxane) (PHMBS);
poly(p-hydroxy-a-methylbenzylsilsesquioxane-co-p-hydroxybenzylsilsesquiox-
ane) (PHMB/H BS);
poly(p-hydroxy-a-methylbenzylsilsesquioxane-co-methoxybe-
nzylsilsesqu ioxane) (PHMB/MBS);
poly(p-hydroxy-.alpha.-methylbenzylsilses-
quioxane-co-t-butylsilsesquioxane) (PHMB/BS);
poly(p-hydroxy-a-methylbenzy-
lsilsesquioxane-co-cyclohexylsilsesquioxane) (PHMB/CHS);
poly(p-hydroxy-.alpha.-methylbenzylsilsesquioxane-co-phenylsilsesquioxane-
) (PHMB/PS);
poly(p-hydroxy-.alpha.-methylbenzylsilsesquioxane-co-bicycloh-
eptylsilsesquioxane) (PHMB/BHS); and
poly(p-hydroxybenzylsilsesquioxane-co-
-p-hydroxyphenylethylsilsesquioxane) (PHB/HPES).
[0042] The amphiphilic molecules are incorporated on and/or into a
porous carrier to form a composite that facilitates the film
forming process. The composite may be stored in an air tight or
otherwise protected container. The porous carrier may function
and/or look like a sponge.
[0043] In order to facilitate loading the porous carrier with the
amphiphilic molecules, the amphiphilic molecules may be optionally
combined with a solvent. Either the mixture of solvent and
amphiphilic molecules or the amphiphilic molecules (without
solvent) is then contacted with the porous carrier for a sufficient
time to permit the mixture/amphiphilic molecules to infiltrate the
pores. In this connection, the porous carrier may be dipped in the
mixture/amphiphilic molecules or the mixture/amphiphilic molecules
may be sprayed or poured on the porous carrier. Alternatively, the
amphiphilic molecules may be melted and contacted with the porous
carrier, the amphiphilic molecules may be combined with a solvent,
then contacted the porous carrier, or the amphiphilic molecules may
be injected in the porous carrier using a syringe. Regardless of
how the amphiphilic molecules are incorporated into the porous
carrier, it is desirable that the amphiphilic molecules are
substantially uniformly distributed throughout the porous
carrier.
[0044] Solvents to which the amphiphilic molecules may be combined
are generally non-polar organic solvents. Such solvents typically
include alcohols such as isopropanol; alkanes such as cyclohexane
and methyl cyclohexane; aromatics such as toluene,
trifluorotoluene; alkylhaolsilanes, alkyl or fluoralkyl substituted
cyclohexanes; ethers; perfluorinated liquids such as
perfluorohexanes; and other hydrocarbon containing liquids.
Examples of perfluorinated liquids include those under the trade
designation Fluorinert T and Novec.TM. available from 3M. When
combining the amphiphilic molecules with one or more solvents, heat
may be optionally applied to facilitate formation of a uniform
mixture.
[0045] A film forming catalyst and/or a quencher may be combined
with the amphiphilic material or mixture of amphiphilic material
and solvent to facilitate the film formation process. Film forming
catalysts include metal chlorides such as zinc chloride and
aluminum chloride, and mineral acids while quenchers include zinc
powders and amines. Each is present in the amphiphilic material or
mixture of amphiphilic material and solvent in an amount from about
0.01% to about 1% by weight.
[0046] The porous carrier impregnated with the mixture of
amphiphilic material and solvent is treated to remove the solvent
or substantially all of the solvent by any suitable means. For
example, evaporation or vacuum distillation may be employed. After
solvent is removed, or in the event the porous carrier is
impregnated with amphiphilic material without the use of solvent,
heat is applied until a constant weight is achieved. In this
instance, heating at a temperature from about 40 to about
100.degree. C. is useful. In most instances, the amphiphilic
material solidifies, becomes semi-solid, or becomes a low viscosity
liquid and is retained in the pores of the porous carrier.
[0047] The porous carrier may be made of any material inert to the
amphiphilic molecules, such as metals, metal oxides, and ceramics.
When a metal is employed as the porous carrier material, the porous
carrier may be referred to as a metal sponge. Examples of materials
that may form the porous carrier include one or more of alumina,
aluminum silicate, aluminum, brass, bronze, chromium, copper, gold,
iron, magnesium, nickel, palladium, platinum, silicon carbide,
silver, stainless steel, tin, titanium, tungsten, zinc, zirconium,
Hastelloy.RTM., Kovar.RTM., Invar, Monel.RTM., lnconel.RTM., and
various other alloys.
[0048] Such materials in powder, granuole, and/or fiber form are
compressed to provide the porous carrier, or compressed and
sintered. Any resultant shape may be employed. Shapes of the
compressed porous carrier materials include cylindrical, spherical,
oval, tablet, disc, plugs, pellets, cubes, rectangles, conical, of
any size consistent with a particular application. Referring to
FIGS. 1 to 3, various shapes/sizes of a porous carrier are
illustrated. In each figure, a porous material 10 contains pores 12
which holds the amphiphilic molecules.
[0049] In one embodiment, the porous carrier contains pores having
an average pore size from about 1 micron to about 1,000 microns. In
another embodiment, the porous carrier contains pores having an
average pore size from about 5 microns to about 500 microns. In yet
another embodiment, the porous carrier contains pores having an
average pore size from about 10 microns to about 200 microns. In
still yet another embodiment, the porous carrier contains pores
having an average pore size from about 20 microns to about 100
microns. The size of the pores may be controlled by adjusting the
size of the particulates initially compressed together.
[0050] Examples of porous carriers include those under the trade
designation Mott Porous Metal, available from Mott Corporation;
those under the trade designation Kellundite available from Filtros
Ltd.; and those under the trade designations Metal Foam, Porous
Metal Media and Sinterflo.RTM., available from Provair Advanced
Materials Inc.
[0051] In one embodiment, the porous carrier has a porosity so that
it can absorb from about 0.001 g to about 5 g of amphiphilic
material per cm.sup.3 of porous carrier. In another embodiment, the
porous carrier has a porosity so that it can absorb from about 0.01
g to about 2 g of amphiphilic material per cm.sup.3 of porous
carrier. In yet another embodiment, the porous carrier has a
porosity so that it can absorb from about 0.05 g to about 1 g of
amphiphilic material per cm.sup.3 of porous carrier. In one
embodiment in these porosity amounts, the amphiphilic material
includes the amphiphilic molecules and solvent. In another
embodiment in these porosity amounts, the amphiphilic material
includes the amphiphilic molecules without solvent.
[0052] The methods and composites of the present invention are
advantageous for providing thin films on substrates. Substrates
include those with porous and non-porous surfaces such as glasses,
glass having an antireflection coating such as magnesium fluoride,
silica (other metal oxides), germanium oxide, ceramics, porcelains,
fiberglass, metals, and organic materials including thermosets such
as polycarbonate, and thermoplastics. Additional organic materials
include polystyrene and its mixed polymers, polyolefins, in
particular polyethylene and polypropylene, polyacrylic compounds,
polyvinyl compounds, for example polyvinyl chloride and polyvinyl
acetate, polyesters and rubber, and also filaments made of viscose
and cellulose ethers, cellulose esters, polyamides, polyurethanes,
polyesters, for example polyglycol terephthalates, and
polyacrylonitrile.
[0053] Glasses specifically include lenses, such as eyewear lenses,
microscope slides, binocular lenses, microscope lenses, telescope
lenses, camera lenses, video lenses, televison screens, computer
screens, LCDs, mirrors, prisms, and the like. Substrates may have a
primer layer of a material desired to improve adhesion between the
substrate surface and the amphiphilic molecules.
[0054] Employing the porous carrier of the present invention, the
amphiphilic molecules are applied as a thin film to a substrate
surface using any suitable thin film forming technique. The porous
carrier contributes to the efficient delivery of amphiphilic
molecules to the substrate surface, while minimizing or eliminating
damage to the substrate and minimizing waste of the amphiphilic
molecules.
[0055] Film forming techniques involve exposing the substrate to
the amphiphilic molecules incorporated on the porous carrier in a
chamber or closed environment under at least one of reduced
pressure, elevated temperature, irradiation, and power. Preferably,
reduced pressure and/or elevated temperatures are employed. The
reduced pressure, elevated temperatures, irradiation, and/or power
imposed induce vaporization or sublimation of the amphiphilic
molecules into the chamber atmosphere and subsequent self assembly
and/or self-polymerization on the substrate surface in a uniform
and continuous fashion thereby forming the thin film.
[0056] In one embodiment, the substrate is exposed to the
amphiphilic molecules under a pressure from about 0.000001 to about
760 torr. In another embodiment, the substrate is exposed to the
amphiphilic molecules under a pressure from about 0.00001 to about
200 torr. In yet another embodiment, the substrate is exposed to
the amphiphilic molecules under a pressure from about 0.0001 to
about 100 torr.
[0057] In one embodiment, the composite/porous carrier is heated to
a temperature from about 20 to about 400.degree. C. In another
embodiment, the composite/porous carrier is heated to a temperature
from about 40 to about 3500 C. In yet another embodiment, the
composite/porous carrier is heated to a temperature from about 50
to about 300.degree. C. Only the composite/porous carrier needs to
be at the temperature described above to induce film formation. The
substrate is at about the same or at a different temperature as the
composite/porous carrier in the chamber. The composite/porous
carrier is at about the same or at a different temperature as the
atmosphere of the chamber. The substrate is at about the same or at
a different temperature as the atmosphere of the chamber. In one
embodiment, each of the substrate, composite, and atmosphere is at
a temperature from about 20 to about 400.degree. C.
[0058] In one embodiment, the amount of amphiphilic material used
is from about 1.times.10.sup.-3 mmole/ft.sup.3 to about 10
mmole/ft.sup.3 of chamber volume. In another embodiment, the amount
of amphiphilic material used is from about 1.times.10.sup.-2
mmole/ft.sup.3 to about 1 mmole/ft.sup.3 of chamber volume.
[0059] In one embodiment, the substrate and the amphiphilic
material remains in contact for a time from about 10 seconds to
about 24 hours (under specified temperature and pressure). In
another embodiment, the substrate and the amphiphilic material
remains in contact for a time from about 30 seconds to about 1
hour. Alternatively, time limitations can be ignored so long as the
film thickness is monitored so that the process may be terminated
after the desired thickness is achieved.
[0060] The film formation rate is primarily dependent upon one or
more of the identity of the amphiphilic material, the identity of
the porous carrier, and the film formation conditions (temperature,
pressure, and the like). In one embodiment, the film formation rate
is about 0.01 nm/sec or more and about 1 nm/sec or less (nm in film
thickness). In another embodiment, the film formation rate is about
0.05 nm/sec or more and about 0.5 nm/sec or less.
[0061] General examples of film forming techniques include vacuum
deposition; vacuum coating; box coating; sputter coating; vapor
deposition or chemical vapor deposition (CVD) such as low pressure
chemical vapor deposition (LPCVD), plasma enhanced chemical vapor
deposition (PECVD), high temperature chemical vapor deposition
(HTCVD); and sputtering. Such techniques are known in the art and
not described for brevity sake.
[0062] Vapor deposition/chemical vapor deposition techniques and
processes have been widely disclosed in literature, for example:
Thin Solid Films, 1994, 252, 32-37; Vacuum technology by Ruth A.
3.sup.rd edition, Elsevier Publication, 1990, 311-319; Appl. Phys.
Left. 1992, 60, 1866-1868; Polymer Preprints, 1993, 34,427-428;
U.S. Pat. Nos. 6,265,026; 6,171,652; 6,051,321; 5,372,851; and
5,084,302, which are hereby incorporated by reference for their
teachings in forming films or depositing organic compounds on
substrates.
[0063] Referring to FIG. 4, a method and system for forming thin
films is described. Generally speaking, a chamber 20 such as a
vacuum chamber is employed for use in the present invention. The
chamber may be an insulated rectangular metal box having a door
which is sealed by a gasket when closed and allows insertion and
removal of items. The box can have an inside chamber that is
optionally attached to a high vacuum pump 22 capable of drawing a
vacuum of, for example, 0.0001 torr. Examples of chambers include
those under the trade designation Satis, such as MC LAB 260, MC LAB
360, 900 DLS, 1200 TLS, and 150 available from Satis Vacuum AG;
those under the trade designation Univex, such as 300, 350, and 400
available from Leybold Vacuum; those under the trade designation
Integritye 36, 39, 44, and 50 available from Denton Vacuum; and
those under the trade designation Balinit.RTM. available from
Balzers.
[0064] The chamber can be equipped with separate heating devices
for at least one of heating the chamber 24, heating/vaporizing the
amphiphilic material 26 and heating the substrates 28. A number of
different devices such as resistance electrodes, a resistance
heater, an induction coil, or an electron or laser beam can be used
for rapidly heating the amphiphilic materials to a high temperature
for vaporization. An electric heater block may be used for this
purpose. The heater may heat a crucible 30 in which the composite
32 is placed.
[0065] The substrates 34 to be coated with a thin, hydrophobic film
in accordance with the invention are placed inside the chamber, in
any suitable position. The composite 32 of a porous carrier and
amphiphilic material is also placed in contact with a heating
device 26 inside the chamber 20 and the door is closed. Although a
cone arrangement is shown, the composite 32 of a porous carrier and
amphiphilic material and substrates 34 may be positioned in any
manner. A strong vacuum from about 2.times.10.sup.+2 to about
5.times.10.sup.-4 torr is optionally applied to the chamber 20. A
valve 36 connecting the pump 22 to the chamber 20 is closed to keep
the chamber 20 at constant high vacuum. The amphiphilic material is
heated quickly to vaporize the material. The gas phase amphiphilic
molecules spread uniformly and very quickly throughout the chamber
20. As the amphiphilic molecules vaporize, the vacuum inside the
chamber may rise slightly but remains within the range from about
2.times.10.sup.+2 to about 5.times.10.sup.-4 torr. The chamber 20
is kept in this condition for a time from about 10 seconds to about
60 minutes or the thickness is monitored by a quartz crystal that
can be mounted in the chamber (to obtain a desired thickness).
During this time the amphiphilic molecules self-assemble and attach
themselves to the surface of the substrates 34 and form a
continuous, uniform thin film. The substrate 34 may be rotated to
promote uniform application of the amphiphilic material over the
substrates 34.
[0066] After the selected time, the vacuum pump valve 36 is opened
to evacuate the excess gas phase amphiphilic material from the
chamber 20. A cold trap or condenser may be optionally employed
between the chamber and the pump to condense and trap the excess
amphiphilic material vapor so that it does not escape to the
atmosphere. Clean air is let into the chamber 20 through another
valve 38 thereby bringing it up to atmospheric pressure and the
chamber 20 is opened to remove the coated substrates 34.
[0067] The film forming composition may be characterized by FTIR
and/or NMR using known methods in the art. Other chemical
properties such as % of hydroxyl groups may be determined by
methods known in the art such as U.S. Pat. No. 4,745,169. Still
other physical properties and spectroscopic characterization
methods may be employed and are known in the art.
[0068] The amphiphilic material and/or film formed therefrom has
reactive hydroxyl groups, which become involved in chemical bonding
(hydrogen and/or covalent) to the substrate. As the substrate
surface reacts with moisture (airborne water molecules), making
covalent bonds to the surface, similar to self-assembley of layers,
thus providing permanent transparent uniform thin film, which is
resistant to many drastic conditions; that is, retaining its
excellent hydrophobic/oleophobic properties.
[0069] The film provides several advantages on these surfaces
including scratch resistance, protection of anti-reflective
coatings on eyewear lenses, protect surfaces from corrosion,
moisture barrier, friction reduction, anti-static, stain
resistance, fringerprint resistance, and the like. The film is
typically hydrophobic in nature.
[0070] The thin film formed on the substrate using the composite of
a porous carrier impregnated with the amphiphilic molecules has a
uniform thickness over the substrate. In one embodiment, the
thickness of the resultant thin film is from about 1 nm to about
250 nm. In another embodiment, the thickness of the resultant thin
film is from about 2 nm to about 200 nm. In yet another embodiment,
the thickness of the resultant thin film is from about 5 nm to
about 100 nm. In still yet another embodiment, the thickness of the
resultant thin film is from about 8 nm to about 20 nm. The
thickness of the thin film may be controlled by adjusting the
deposition parameters, for example, the length of time the
substrate and the composite remain in the chamber under at least of
reduced pressure, elevated temperature, irradiation, and/or
power.
[0071] In one embodiment, the thin film is relatively uniform in
that, assuming the substrate has a planar surface, the thickness of
the thin film does not vary by more than about 25 nm over the
surface of the planar portion of the substrate. In another
embodiment, the thin film is relatively uniform in that the
thickness of the thin film does not vary by more than about 15 nm
over the surface of the planar portion of the substrate.
[0072] The thin film formed on the substrate using the composite of
a porous carrier impregnated with the amphiphilic molecules is
continuous in nature. In other words, pinholes and other film
defects in thin films made in accordance with the present invention
are minimized and/or eliminated.
[0073] In one embodiment, when using a POSS polymer as the
amphiphilic material and a glass as the substrate, formation of a
layer of silica (or other metal oxide) and amphiphilic material
thin film may be conducted in a single chamber. This is because it
is not necessary to expose the silica layer to water vapor when
forming POSS polymer amphiphilic material layer thereover.
Moreover, the formation of any POSS polymer amphiphilic material
layer on the interior of the chamber is not harmful, and does not
prevent subsequent and repeated use of the chamber for the
aforementioned two step process.
[0074] The following examples illustrate the present invention.
Unless otherwise indicated in the following examples and elsewhere
in the specification and claims, all parts and percentages are by
weight, all temperatures are in degrees Centigrade, and pressure is
at or near atmospheric pressure.
Example 1
[0075] Three liters of distilled water is placed in a 5 l beaker.
The beaker is then chilled to about 5.degree. C. and the
temperature is maintained by circulation through a chiller to
maintain the temperature, however any method known in the art for
maintaining temperature, such as adding ice may be employed.
Octadecyltrichlorosilane (300 g) is added dropwise while stirring
and maintaining the temperature. The solution is then hydrolyzed to
yield a fine crystalline material. The reaction mixture is further
stirred for approximately 30 minutes while continuing to maintain
temperature. The reaction mixture is then allowed to return to room
temperature while being stirred. After returning to room
temperature, the reaction mixture is stirred for approximately 10
hours. The reaction mixture is then filtered and washed with water
to remove all acid, and then dried. While the mixture is air dried
and then oven dried at 95.degree. C. for 2 hours, other methods of
drying as are known in the art may alternatively be utilized. After
drying the mixture, a white powder having a melting point of 70-
72.degree. C. is provided.
Example 2
[0076] The procedure of Example 1 is repeated except that
heptadecafluoro-1,1,2,2-tetrahydrodecyl trichlorosilane is used in
place of octadecyltrichlorosilane. After drying the mixture, a
white powder having a melting point of 67.degree. C. is
provided.
Example 3
[0077] The procedure of Example 1 is repeated except that octyl
trichlorosilane is used in place of octadecyltrichlorosilane. After
drying the mixture, a very thick clear oil is provided.
Example 4
[0078] Hexadecyl trimethoxysilane (25 g), 15 ml of distilled water,
40 ml of 2-propanol and 2 ml of concentrated HCl are stirred in a
250 ml flask. The mixture becames a white thick precipitate in a
few minutes and becomes difficult to stir. An additional 100 ml of
a 50:50 water-2 propanol mixture is added and the reaction mixture
is stirred at room temperature for 10 hours and later heated to
70.degree. C. for 2 hours to fully hydrolyze and yield a fine
powder. Isolation and filtration are carried out as per Example 1.
The reaction mixture is then dried in an oven at 98.degree. C. for
2 hours. The mixture becames oily and solidified on standing at
room temperature, and yielded a white, waxy solid, having a melting
point of 65.degree. C.
Example 5
[0079] The procedure of Example 4 is repeated except that a 1:1
molar ratio of tridecafluorooctyl triethoxysilane and hexadecyl
trimethoxysilane is used in place of hexadecyl trimethoxysilane. A
semi-solid is provided.
Example 6
[0080] Tridecafluorooctyl triethoxysilane and hexadecyl
trimethoxysilane having varying weight ratios are mixed together.
In addition, tetraethoxysilane is added so as to comprise about 5%
to about 10% of total weight of the mixture. The mixture is then
and hydrolyzed under the experimental conditions of Examples 4 and
5, however zinc 2-ethylhexoate (zinc octoate) is added as catalyst
for cross-linking agent to the hydrolyzed tetraethoxysilane to
increase the number of reactive sites. Alcohol and water are
removed using a rotavap at reduced pressure. The mixture yielded a
white paste semi-solid.
[0081] While the invention has been explained in relation to
certain embodiments, it is to be understood that various
modifications thereof will become apparent to those skilled in the
art upon reading the specification. Therefore, it is to be
understood that the invention disclosed herein is intended to cover
such modifications as fall within the scope of the appended
claims.
* * * * *