U.S. patent application number 12/545101 was filed with the patent office on 2009-12-17 for polyhedral oligomeric silsesquioxane and carborane containing network.
This patent application is currently assigned to The Government of the United States of America, as represented by the secretary of the Navy. Invention is credited to Teddy M. Keller, Manoj K. Kolel-Veetil.
Application Number | 20090312568 12/545101 |
Document ID | / |
Family ID | 40253691 |
Filed Date | 2009-12-17 |
United States Patent
Application |
20090312568 |
Kind Code |
A1 |
Keller; Teddy M. ; et
al. |
December 17, 2009 |
POLYHEDRAL OLIGOMERIC SILSESQUIOXANE AND CARBORANE CONTAINING
NETWORK
Abstract
A thermoset and method of making such by crosslinking a mixture
of a polyhedral oligomeric silsesquioxane having pendent siloxane
groups or unsaturated carbon bonds and a siloxylcarborane compound
having unsaturated carbon bonds.
Inventors: |
Keller; Teddy M.; (Fairfax
Station, VA) ; Kolel-Veetil; Manoj K.; (Alexandria,
VA) |
Correspondence
Address: |
NAVAL RESEARCH LABORATORY;ASSOCIATE COUNSEL (PATENTS)
CODE 1008.2, 4555 OVERLOOK AVENUE, S.W.
WASHINGTON
DC
20375-5320
US
|
Assignee: |
The Government of the United States
of America, as represented by the secretary of the Navy
Washington
DC
|
Family ID: |
40253691 |
Appl. No.: |
12/545101 |
Filed: |
August 21, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11834741 |
Aug 7, 2007 |
|
|
|
12545101 |
|
|
|
|
60948721 |
Jul 10, 2007 |
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Current U.S.
Class: |
556/450 |
Current CPC
Class: |
C08F 283/12 20130101;
C08G 77/20 20130101; C08L 83/14 20130101; C08G 77/12 20130101; C08G
77/50 20130101; C08G 77/04 20130101; C08F 283/00 20130101; C08G
77/56 20130101 |
Class at
Publication: |
556/450 |
International
Class: |
C07F 7/02 20060101
C07F007/02 |
Claims
1. A thermoset made by crosslinking a mixture comprising: a
polyhedral oligomeric silsesquioxane having pendent unsaturated
carbon bonds; and a siloxylcarborane compound having unsaturated
carbon bonds; wherein the crosslinking occurs between the
unsaturated carbon bonds of the polyhedral oligomeric
silsesquioxane and unsaturated carbon bonds of the siloxylcarborane
compound.
2. The thermoset of claim 1, wherein the siloxylcarborane compound
is bis(vinyltetramethyldisiloxyl)m-carborane.
3. The thermoset of claim 1, wherein the polyhedral oligomeric
silsesquioxane is: ##STR00012##
4. The thermoset of claim 1, wherein a siloxane curing agent having
silyl hydrogens is used as a curing agent.
5. The thermoset of claim 4; wherein the polyhedral oligomeric
silsesquioxane is ((CH.sub.2.dbd.CH)SiO.sub.1.5).sub.8; and wherein
the siloxane curing agent is tetrakis(dimethylsiloxyl)silane,
methyltris(dimethylsiloxyl)silane, or phenyltris(dimethylsiloxyl)
silane.
6. A method comprising: crosslinking a mixture comprising: a
polyhedral oligomeric silsesquioxane having pendent unsaturated
carbon bonds; and a siloxylcarborane compound having unsaturated
carbon bonds; wherein the crosslinking occurs between the
unsaturated carbon bonds of the polyhedral oligomeric
silsesquioxane and unsaturated carbon bonds of the siloxylcarborane
compound.
7. The method of claim 6, wherein the siloxylcarborane compound is
bis(vinyltetramethyldisiloxyl)m-carborane.
8. The method of claim 6, wherein the polyhedral oligomeric
silsesquioxane is: ##STR00013##
9. The method of claim 6, wherein a siloxane curing agent having
silyl hydrogens is used as a curing agent.
10. The thermoset of claim 9; wherein the polyhedral oligomeric
silsesquioxane is ((CH.sub.2.dbd.CH)SiO.sub.1.5).sub.8; and wherein
the siloxane curing agent is tetrakis(dimethylsiloxyl)silane,
methyltris(dimethylsiloxyl)silane, or phenyltris(dimethylsiloxyl)
silane.
Description
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/834,741, pending and filed on Aug.
7, 2007, which claims the benefit if U.S. Provisional Application
No. 60/948,721 filed on Jul. 10, 2007. This application and all
other referenced patent documents and publications throughout this
application are incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The invention is generally related to polymers containing
polyhedral oligomeric silsesquioxane (POSS) groups and carborane
groups.
DESCRIPTION OF RELATED ART
[0003] POSS systems have found use in hybrid inorganic/organic
polymers. Ladder-like silsequioxane polymers have found
applications in photoresist coatings for electronic and optical
devices, interlayer dielectrics and protective coating films for
semiconductor devices, liquid crystal display elements, magnetic
recording media, optical fiber coatings, gas separation membranes,
binders for ceramics and as carcinostatic drugs (Li et al., J.
Inorg. Organomet. Polym. 2002, 11(3), 123-154). In the area of
surface modification and corrosion prevention, POSS systems have
been used as surface modifiers, dispersion agents, coupling agents,
crosslinking agents, adhesion promoters, co-monomers, moisture
scavengers and corrosion protection agents. In biomedical science,
POSS has been used in place of fumed-silica which is typically used
as a filler for improving the chemical, physical and biological
properties of membranes used in immunoisolatory applications
(Pittman et al., J. Macromol. Symp. 2003, 196, 301-325).
[0004] Carborane-containing polymers have found applications as
conducting polymers (Masalles et al., Adv. Mater. 2002, 14,
826-837), cancer treatment agents in medicine (Thomas et al., Chem.
Comm. 2001, 1884-1885), precursors for high performance fibers (Wei
et al., Chem. Mater. 2006, 18, 1113-1122), supported organic
catalysts (Yinghuai et al., J. Organomet. Chem. 2005, 690,
2802-2835), and in supramolecular assembly geared towards the
production of nanomaterials (Wedge et al., Coord. Chem. Rev. 2003,
240, 111-162). In particular, polymers containing siloxane and
carborane groups can exhibit exceptional thermal and
thermo-oxidative properties (Dvornic et al., High Temperature
Siloxane Elastomers, Huthig & Wepf, Heidelberg (1990)).
Carborane groups improve the thermal and thermo-oxidative
properties of siloxane polymers due to their chemical inertness
arising from their low nucleophilicity, high hydrophobicity, and
electron-withdrawing properties since they possess a highly
polarizable .sigma.-aromatic character (Williams, "Carboranes",
(Chapter 2) in "Progress in Boron Chemistry", Vol. 2, Pergamon
Press, New York (1970); Dunks et al., Acc. Chem. Res. 6 (1973)
124-142). Siloxane polymers containing carboranes, hence, can be
used as high-temperature plastic, elastomeric, and ceramic
materials especially in the aerospace and defense industries for
applications in sealing assemblies of landing gears, flight control
and fuel systems, and for cable insulations. The demand for such
materials also exists for resist layers in the manufacture of
computer chips.
[0005] Hydrosilation reactions of the carboranylenesiloxane monomer
2 with branched siloxane crosslinkers can produce high temperature
elastomeric carboranylenesiloxane network polymers with exceptional
thermal, thermo-oxidative and optical properties (Kolel-Veetil et
al., J. Polym. Sci. Part A: Polym. Chem., 2006, 44, 147-156). The
reactions involved ambient condition hydrosilation reactions of the
reactants in the presence of the heterogeneous hydrosilation
catalyst known as the Karstedt catalyst (platinum-divinyl siloxane
catalyst). The reactions were performed in hexane. These facile
reactions can produce flexible and transparent network films of the
anticipated product.
[0006] The base-catalyzed hydrolysis of Si--H to Si--OH and the
ensuing condensation of Si--OH and Si--H groups to Si--O--Si
bridges has been the subject of detailed investigations (Null,
Chemistry and Technology of Silicones, Academic Press (1968)).
Pt-based catalysts such as the Karstedt catalyst can promote such
hydrolysis and condensation of Si--OH and Si--H groups in the
presence of a base such as triethylamine (Et.sub.3N) and water
(Kurian et al., J. Polym. Sci. Part A: Polym. Chem., 2002, 40,
1285-1292). The Karstedt catalyst was proposed to oxidize Si--H to
Si--OH, whereas the Et.sub.3N co-catalyst was proposed to mediate
the condensation of Si--OH to Si--O--Si (Lewis, J. Am. Chem. Soc.,
1990, 112, 5998-6004). Such reactions have been utilized in the
formation of amphiphilic membranes that are crosslinked and
reinforced by POSS (Isayeva et al., J. Polym. Sci. Part A: Polym.
Chem., 2004, 42, 4337-4352).
SUMMARY OF THE INVENTION
[0007] The invention comprises a thermoset made by crosslinking a
mixture comprising: a polyhedral oligomeric silsesquioxane having
pendent siloxane groups or unsaturated carbon bonds; and a
siloxylcarborane compound having unsaturated carbon bonds.
[0008] The invention further comprises a method comprising
crosslinking the above mixture.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] A more complete appreciation of the invention will be
readily obtained by reference to the following Description of the
Example Embodiments and the accompanying drawings.
[0010] FIG. 1 shows char yields in air (dotted line) and in N.sub.2
(solid line) of the POSS-carborane crosslinked network containing
only hydrosilated --Si--CH.sub.2--CH.sub.2--Si-- linkages.
[0011] FIG. 2 shows char yields in air (dotted line) and in N.sub.2
(solid line) of the POSS-carborane crosslinked network containing
both the hydrosilated --Si--CH.sub.2--CH.sub.2--Si-- linkages and
the --Si--O--Si-- linkages.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0012] In the following description, for purposes of explanation
and not limitation, specific details are set forth in order to
provide a thorough understanding of the present invention. However,
it will be apparent to one skilled in the art that the present
invention may be practiced in other embodiments that depart from
these specific details. In other instances, detailed descriptions
of well-known methods and devices are omitted so as to not obscure
the description of the present invention with unnecessary
detail.
[0013] Disclosed herein is a method for the production of
inorganic-organic hybrid network polymers containing the clusters
of POSSs and carboranes that may possess desirable thermal,
thermo-oxidative, electrical, adhesive (coating/surface), and
membrane properties. The method may utilize hydrosilation and
hydrolysis/condensation reactions in unison involving the POSS and
carboranylenesiloxane materials.
[0014] The properties of a carboranylenesiloxane such as 2 and that
of a POSS monomer such as 1 may render them useful for
incorporation into crosslinked networked system by the utilization
of a combination of hydrosilation and hydrolysis/condensation
reactions. In such compounds, there can be at least two types of
crosslinking linkages such as the --Si--C(H)--C(H)--Si-- linkages
(formed from the hydrosilation reaction) and the --Si--O--Si--
linkages (formed from the hydrolysis/condensation reactions). The
vertices of the polyhedron in 2 are --BH groups, except for
vertices labeled as C.
##STR00001##
[0015] POSSs have the general formula
(RSiO.sub.1.5).sub.a(H.sub.2O).sub.0.5b or rearranged to
R.sub.aSi.sub.aO(.sub.1.5a-0.5b)(OH).sub.b, where a is a positive
integer, b is a non-negative integer, a+b is a positive even
integer, and b.ltoreq.a+2. In a completely condensed POSS, b is
zero and all Si--O--Si bridges are complete as in 1, which shows
a=8 and b=0. In an incompletely condensed POSS, some adjacent pairs
of silicon atoms are not bridged, each containing an OH group.
Suitable POSSs include, but are not limited to, completely
condensed POSS, incompletely condensed POSS, (RSiO.sub.1.5).sub.8,
((SiH(CH.sub.3).sub.2O)SiO.sub.1.5).sub.8 1,
((CH.sub.2.dbd.CH)SiO.sub.1.5).sub.8 3, and the incompletely
condensed trisnorbornenylheptaisobutyl-POSS 4. In 4, R is isobutyl,
a is 7, b is 3, the hydrogens in the general POSS formula are
substituted, and the wavy bonds indicate a racemic mixture of cis-
and trans-norbornenyl groups.
##STR00002##
[0016] The carboranylenesiloxane compound contains at least one
carboranyl group and at least one siloxane group. It may contain a
siloxane oligomer, which may terminate in silicon atoms. The
compound may be a small molecule or a polymer. Suitable
carboranylenesiloxane compounds include, but are not limited to, 2
and the polymer 5. Also, any carboranyl group or
carboranylenesiloxane compound disclosed in U.S. Pat. Nos.
6,967,233 and 5,969,072 may be used.
##STR00003##
[0017] The mixture may also comprise curing agents that may
crosslink with the POSS, the carboranylenesiloxane compound, or
both. The curing agent may be a siloxane compound having
unsaturated carbon bonds, including, but are not limited to,
tetrakis(vinyldimethylsiloxy)silane 6, and a
vinyldimethylsiloxy-bisphenol A-benzophenone adduct such as 7. The
curing agent may also be a siloxane curing agent having silyl
hydrogens, including, but are not limited to,
tetrakis(dimethylsiloxyl)silane 8,
methyltris(dimethylsiloxyl)silane 9, or phenyltris(dimethylsiloxyl)
silane 10.
##STR00004##
[0018] As used herein, crosslinking between two groups refers to
direct reaction between the groups as well as to the use of a
curing agent reacting with both groups. Also, there may be
incomplete crosslinking with unreacted groups, or the crosslinking
may be complete.
[0019] In one embodiment, the thermoset is crosslinked between the
pedant siloxane groups of the POSS and the unsaturated carbon bonds
of the siloxylcarborane compound. This may be done, for example, by
a hydrosilation reaction between the Si-Vinyl groups of 2 and the
Si--H groups of 1. The Karstedt catalyst
(Pt.sub.2{[(CH.sub.2.dbd.CH)Me.sub.2Si].sub.2O}.sub.3) may be used
for this reaction. An example of this crosslinking is shown below,
where the cubes represent the POSS cage of 1 and the rectangles
represent the
--Si(CH.sub.3).sub.2OSi(CH.sub.3).sub.2(CB.sub.10H.sub.10C)Si(CH.sub.3).s-
ub.2OSi(CH.sub.3).sub.2-- of 2.
##STR00005##
[0020] In another embodiment, thermoset is crosslinked between the
pedant siloxane groups, in addition to the crosslinks between the
pedant siloxane groups and the unsaturated carbon bonds. This may
be done, for example, by a self hydrolysis/condensation reaction of
1 and 2 in the presence of the Karstedt catalyst, and catalytic
amounts of triethylamine and water. An example of this is shown
below.
##STR00006##
[0021] In another embodiment, the mixture further comprises a
siloxane compound having unsaturated carbon bonds, such as 6 or 7.
The crosslinking further occurs between the pendant siloxane groups
of the POSS and the unsaturated carbon bonds of the siloxane
compound. An example of this crosslinking is shown below, where the
squares represent the [Si(CH.sub.3).sub.2O].sub.4Si portion of
6.
##STR00007##
[0022] In another embodiment, the siloxylcarborane compound is a
siloxylcarborane/diacetylene polymer. The thermoset is an
interpenetrated networked polymer system of the crosslinked POSS
and the crosslinked siloxylcarborane compound. This may be done,
for example, in the presence of the Karstedt catalyst and catalytic
amounts of triethylamine and water. An example of this crosslinking
is shown below.
##STR00008##
[0023] Under appropriate reaction conditions, the above reactants
may crosslink by hydrosilation between the POSS and the polymer as
shown below. Rh.sub.2(1,5-cyclooctadiene).sub.2(.mu.-Cl).sub.2
(Rh.sub.2(COD).sub.2(.mu.-Cl).sub.2) or platinum diacetylacetonate
(Pt(acac).sub.2) may be used as a catalyst.
##STR00009##
[0024] In another embodiment, the crosslinking occurs between the
unsaturated carbon bonds of the POSS and unsaturated carbon bonds
of the siloxylcarborane compound. For example, when the POSS is 4,
this may be done by a ring opening metathesis polymerization in the
presence of
3-methyl-2-butenylidne-bis(tricyclopropylphosphine)dichlororuthenium.
Crosslinking between the unsaturated carbon bonds of the POSS,
specifically between norbornenyl groups, may also occur. An example
of this embodiment is shown below. (The seven vertices of the open
cubes contain isobutyl groups.)
##STR00010##
[0025] In another embodiment, the crosslinking occurs between the
unsaturated carbon bonds of the POSS and unsaturated carbon bonds
of the siloxylcarborane compound using a siloxane curing agent
having silyl hydrogens. This may be done by hydrosilation reactions
between the curing agent and the POSS and siloxylcarborane
compound. Suitable curing agents include, but are not limited to,
8, 9, and 10. An example of this is shown below. The circles
represent the central portion of the curing agent.
##STR00011##
[0026] The inorganic-organic hybrid carborane-POSS network polymers
incorporate two cluster species of carboranes and POSSs. These
clusters, individually, are known for their exceptional chemical
and material properties. The network polymers may have the
cumulative properties of the two cluster systems. Thermo
gravimetric analysis has shown high char yields in air and in
N.sub.2. In addition, the cooperation of the individual properties
of the two cluster species could present hitherto unavailable
properties such as, for example: (i) the thermo-oxidatively
stability of a POSS-containing photoresist due to the cooperative
enhancement in such a property by the carborane clusters, (ii) the
gas permeation ability of a carborane-containing network polymer
due to the presence of the POSS clusters, (iii) the neutron
capturing ability of a POSS-containing carcinostatic treatment
membrane due to the presence of the neutron-capturing boron atoms
in the carborane clusters.
[0027] In addition, the presence of flexible siloxane units may
render these network films more flexible which may not be singly
achieved from either a carborane or POSS networked polymeric
system. This may enhance the usability of the invented systems in
applications with structural constraints.
[0028] Having described the invention, the following examples are
given to illustrate specific applications of the invention. These
specific examples are not intended to limit the scope of the
invention described in this application.
Example 1
[0029] Crosslinked network containing only hydrosilated
--Si--CH.sub.2--CH.sub.2--Si-- linkages--In a typical reaction,
0.25 g of bis(vinyltetramethyldisiloxyl)m-carborane 2 (0.54 mmol;
M.W.=460.36 g/mol) was taken in a reaction vial with 0.138 g of
octasilane-POSS 1 (0.135 mmol; M.W.=1018 g/mol) and was mixed
thoroughly using a mechanical stirrer. This yielded a
Si--H:Si-vinyl ratio of 1:1 in the reaction mixture. To the
mixture, 5 mL of either CH.sub.2Cl.sub.2 or toluene was added and
the solution was thoroughly mixed using the stirrer to yield a
clear solution. At this point, 2 drops of a 2-2.4 wt % Pt Karstedt
catalyst solution in xylenes were added drop wise which was
followed by 2 minutes each of thorough mixing. The solution became
warmer and appeared yellow in color. The solution in the vial was
then placed on a hot plate for 2 hours (The CH.sub.2Cl.sub.2
solution, at 40.degree. C., and the toluene solution, at 70.degree.
C.). Upon heating, gelation occurred and the mixtures (which were
tough) were transferred from the reaction vials to Teflon molds and
were characterized by thermo gravimetric analysis in air and in
N.sub.2. Char yield of the product (formed from the
CH.sub.2Cl.sub.2 reaction) at 1000.degree. C. in N.sub.2=76.65% and
in air=91.23% (FIG. 1).
Example 2
[0030] Crosslinked network containing both the hydrosilated
--Si--CH.sub.2--CH.sub.2--Si-- linkages and the --Si--O--Si--
linkages--In a typical reaction, 0.25 g of
bis(vinyltetramethyldisiloxyl)m-carborane 2 (0.54 mmol; M.W.=460.36
g/mol) was taken in a reaction vial with 0.276 g of octasilane-POSS
1 (0.135 mmol; M.W.=1018 g/mol) and was mixed thoroughly using a
mechanical stirrer. This yielded a Si--H:Si-vinyl ratio of 2:1 in
the reaction mixture. To the mixture, 5 mL of either
CH.sub.2Cl.sub.2 or toluene was added and the solution was
thoroughly mixed using the stirrer to yield a clear solution. At
this point, 2 drops of a 2-2.4 wt % Pt Karstedt catalyst solution
in xylenes were added drop wise that was followed by 2 minutes each
of thorough mixing. The solution became warmer and appeared yellow
in color. The solution in the vial was then placed on a hot plate
for 2 hours (The CH.sub.2Cl.sub.2 solution, at 40.degree. C., and
the toluene solution, at 70.degree. C.). Upon heating, the solution
remained liquidy in consistency. To this solution, 50 .mu.L each of
Et.sub.3N and distilled water were added in succession when the
mixture was seen to turn turbid (milky white in appearance). The
mixtures were then transferred from the reaction vials to Teflon
molds and were heated on a hotplate between 100-125.degree. C. for
30 min during which complete gelation was observed to occur. The
gelated films (which were tough) were characterized by thermo
gravimetric analysis in air and in N.sub.2. Char yield of the
product (formed from the CH.sub.2Cl.sub.2 reaction) at 1000.degree.
C. in N.sub.2=81.24% and in air=99.28% (FIG. 2).
Example 3
[0031] Crosslinked network from hydrosilation reaction of octavinyl
POSS 3 and bis(vinyltetramethyldisiloxyl)m-carborane 2 with the
crosslinking siloxane 8, 9, or 10--In a typical reaction, 0.182 g
of bis(vinyltetramethyldisiloxyl)m-carborane 2 (0.395 mmol;
M.W.=460.36 g/mol) was taken in a reaction vial with 0.250 g of
octavinyl-POSS 3 (0.395 mmol; M.W.=633.05 g/mol) and was mixed
thoroughly using a mechanical stirrer. To this mixture was taken
0.405 g or 0.458 mL of tetrakis(dimethylsiloxyl)silane 8 (0.989
mmol; M.W.=328.73 g/mol, d=0.886), 0.354 g or 0.410 mL of
methyltris(dimethylsiloxyl)silane 9 (1.319 mmol; M.W.=268.61 g/mol,
d=0.861), or 0.436 g or 0.462 mL of phenyltris(dimethylsiloxyl)
silane 10 (1.319 mmol; M.W.=330.68 g/mol, d=0.942). This yielded a
Si--H:Si-vinyl ratio of 1:1 in the reaction mixture. To the
mixture, 5 mL of either CH.sub.2Cl.sub.2 or toluene was added and
the solution was thoroughly mixed using the stirrer to yield a
clear solution. At this point, 2 drops of a 2-2.4 wt % Pt Karstedt
catalyst solution in xylenes were added drop wise which was
followed by 2 minutes each of thorough mixing. The solution became
warmer and appeared yellow in color. The solution in the vial was
then placed on a hot plate for 2 hours (The CH.sub.2Cl.sub.2
solution, at 40.degree. C., and the toluene solution, at 70.degree.
C.). Upon heating, gelation occurred and the mixtures (which were
tough) were transferred from the reaction vials to Teflon molds and
were characterized by thermo gravimetric analysis in air and in
N.sub.2. Char yield of the product (formed from the
CH.sub.2Cl.sub.2 reaction) at 1000.degree. C. in N.sub.2=74.34%
(8), 71.28% (9) or 73.55% (10) and in air=90.86% (8), 88.53% (9) or
90.01% (10).
Example 4
[0032] Crosslinked network from ring opening metathesis
polymerization of trisnorbornenylisobutyl-POSS 4 and
bis(vinyltetramethyldisiloxyl)m-carborane 2 catalyzed by
3-methyl-2-butylidene-bis(tricyclopropylphosphine)-dichlororuthenium--In
a typical reaction, 0.250 g of
bis(vinyltetramethyldisiloxyl)m-carborane 2 (0.543 mmol;
M.W.=460.36 g/mol) was taken in a reaction vial under argon with
0.720 g of trisnorbornenylisobutyl-POSS 4 (0.543 mmol; M.W.=1326.45
g/mol) and was dissolved in 15 mL of THF. To this mixture was added
25 mg of the
3-methyl-2-butylidene-bis(tricyclopropylphosphine)dichlororuthenium
catalyst. The mixture was heated at 80.degree. C. for 10 hours and
after which the product was recovered by removing the THF solvent
under vacuum. Char yield of the product at 1000.degree. C. in
N.sub.2=71.34% and in air=83.02%.
Example 5
[0033] Interpenetrating crosslinked network simultaneous thermal
crosslinking of poly(carboranylenesiloxane) 5 and self
hydrolysis/condensation reaction of octasilane-POSS 1 in presence
of the Karstedt catalyst--In a typical reaction, 0.250 g of the
poly(carboranylenesiloxane) 5 (0.550 mmol; M.W.=454.87 g/mol) and
0.560 g of octasilane-POSS 4 (0.550 mmol; M.W.=1018.00 g/mol) were
taken together in a vial and were mixed thoroughly using a
mechanical stirrer. To the mixture, 5 mL of either CH.sub.2Cl.sub.2
was added and the solution was thoroughly mixed using the stirrer
to yield a clear solution. At this point, 2 drops of a 2-2.4 wt %
Pt Karstedt catalyst solution in xylenes were added drop wise that
was followed by 2 minutes each of thorough mixing. The solution in
the vial was then placed on a hot plate for 2 hours at 40.degree.
C. To this solution, 50 .mu.L each of Et.sub.3N and distilled water
were added in succession. The mixtures were then transferred from
the reaction vials to Teflon molds and were heated on a hotplate
under argon between 100-125.degree. C. for 30 min during which
gelation was observed to occur. The films were further heated at
250.degree. C. for two hours to initiate the thermal crosslinking
of 5. The film was removed from the Teflon mold and was placed in
an oven on a copper bar and was heated at 400.degree. C. for 2
hours. The interpenetrated networked film was characterized by
thermo gravimetric analysis in air and in N.sub.2. Char yield of
the product at 1000.degree. C. in N.sub.2=88.24% and in
air=99.88%.
Example 6
[0034] Crosslinked network from hydrosilation reaction of
bis(vinyltetramethyldisiloxyl)m-carborane 2 and
tetrakis(vinyldimethylsiloxy)silane 6 with octasilane-POSS 1--In a
typical reaction, 0.182 g of
bis(vinyltetramethyldisiloxyl)m-carborane 2 (0.395 mmol;
M.W.=460.36 g/mol) was taken in a reaction vial with 0.171 g of
tetrakis(vinyldimethylsiloxy)silane 6 (0.395 mmol; M.W.=432.88
g/mol) and was mixed thoroughly using a mechanical stirrer. To this
mixture was taken 0.301 g of octasilane-POSS 1 (0.296 mmol;
M.W.=1018.00 g/mol). This yielded a Si--H:Si-vinyl ratio of 1:1 in
the reaction mixture. To the mixture, 5 mL of either
CH.sub.2Cl.sub.2 or toluene was added and the solution was
thoroughly mixed using the stirrer to yield a clear solution. At
this point, 2 drops of a 2-2.4 wt % Pt Karstedt catalyst solution
in xylenes were added drop wise which was followed by 2 minutes
each of thorough mixing. The solution became warmer and appeared
yellow in color. The solution in the vial was then placed on a hot
plate for 2 hours (The CH.sub.2Cl.sub.2 solution, at 40.degree. C.,
and the toluene solution, at 70.degree. C.). Upon heating, gelation
occurred and the mixtures (which were tough) were transferred from
the reaction vials to Teflon molds and were characterized by thermo
gravimetric analysis in air and in N.sub.2. Char yield of the
product (formed from the CH.sub.2Cl.sub.2 reaction) at 1000.degree.
C. in N.sub.2=79.39% and in air=88.52%.
Example 7
[0035] Crosslinked network from hydrosilation reaction of
bis(vinyltetramethyldisiloxyl)m-carborane 2 and bisphenol
A/benzophenone vinylsilane 7 with octasilane-POSS 1 catalyzed by
platinum cyclovinylmethylsiloxane complex in
cyclicmethylvinylsiloxanes 2.0-2.5 wt %--In a typical reaction,
0.600 g of bisphenol A/benzophenone vinylsilane 7 (0.747 mmol;
M.W.=803.12 g/mol) was taken in a reaction vial with 0.060 g of
bis(vinyltetramethyldisiloxyl)m-carborane 2 (0.130 mmol;
M.W.=460.36 g/mol) (10% by weight of 7) and was mixed thoroughly
using a mechanical stirrer. To this mixture was taken 0.230 g of
octasilane-POSS 1 (0.219 mmol; M.W.=1018.00 g/mol). This yielded a
Si--H:Si-vinyl ratio of 1:1 in the reaction mixture. To the
mixture, 5 mL of either CH.sub.2Cl.sub.2 or toluene was added and
the solution was thoroughly mixed using the stirrer to yield a
clear solution. At this point, 2 drops of a 2-2.5 wt % platinum
cyclovinylmethylsiloxane complex in cyclicmethylvinylsiloxanes were
added drop wise which was followed by 2 minutes each of thorough
mixing. The solution became warmer and appeared yellow in color.
The solution in the vial was then placed on a hot plate for 2 hours
(The CH.sub.2Cl.sub.2 solution, at 40.degree. C., and the toluene
solution, at 70.degree. C.). Upon heating, gelation occurred and
the mixtures (which were tough) were transferred from the reaction
vials to Teflon molds and were characterized by thermo gravimetric
analysis in air and in N.sub.2. Char yield of the product (formed
from the CH.sub.2Cl.sub.2 reaction) at 1000.degree. C. in
N.sub.2=81.39% and in air=93.52%.
Example 8
[0036] Crosslinked network from hydrosilation reaction of
octasilane-POSS 1 with poly(carboranylenesiloxane) 5 in presence of
Rh.sub.2(COD).sub.2(.mu.-Cl).sub.2 catalyst--A flame-dried 50 mL
Schlenk flask was charged with 10 mg (0.0201 mmol) of
Rh.sub.2(COD).sub.2(.mu.-Cl).sub.2 under argon in a dry box. A 2 mL
solution of 0.230 g of octasilane-POSS 1(0.219 mmol; M.W.=1018.00
g/mol) in anhydrous toluene was prepared in another flame-dried
flask. This solution was transferred via cannula into the flask
containing the catalyst. A 5 mL solution of 0.100 g (0.219 mmol;
M.W.=454.87 g/mol) of poly(carboranylenesiloxane) 5 in toluene,
prepared in a third flame-dried flask, was syringed into the
mixture to yield a mixture with a Si--H:--C.dbd.C-- ratio of 2:1.
The mixture was introduced into an oil bath at 70.degree. C. The
reaction was instantaneous as evidenced by the darkening of the
color of the mixture. The mixture was stirred for 30 min at this
temperature and then the volatiles were removed with vacuum. A
cured gel resulted. Thermal properties: char yield at 1000.degree.
C. (in N.sub.2): 82.52%, char yield at 1000.degree. C. (in air):
95.23%.
Example 9
[0037] Crosslinked network from hydrosilation reaction of
octasilane-POSS 1 with poly(carboranylenesiloxane) 5 in presence of
the photochemical catalyst, Pt(acac).sub.2--A flame-dried quartz
photochemical reaction tube was charged with 10 mg (0.0254 mmol) of
Pt(acac).sub.2 under Ar in a dry box. 1 mL of CH.sub.2Cl.sub.2 was
added to it to yield a pale yellow catalyst solution. In a separate
vial, a 2 mL solution of 0.230 g of octasilane-POSS 1 (0.219 mmol;
M.W.=1018.00 g/mol) was prepared in CH.sub.2Cl.sub.2. This solution
was transferred into the reaction tube containing the catalyst. A 5
mL solution of 0.100 g (0.219 mmol; M.W.=454.87 g/mol) of
poly(carboranylenesiloxane) 5, in CH.sub.2Cl.sub.2, prepared in
another vial, was syringed into the mixture to yield a mixture with
a Si--H:--C.dbd.C-- ratio of 2:1. The reaction tube was inserted
into a Rayonet Photochemical reaction instrument. The sample was
irradiated for 30 min using a >300 nm (Pyrex filtered) radiation
while being constantly agitated by a stream of argon which was
passed via needle. After this period, the irradiation was stopped
and the quartz tube was taken out of the reactor. The formation of
a cured gel was observed. Thermal properties: char yield at
1000.degree. C. (in N.sub.2): 80.12%, char yield at 1000.degree. C.
(in air): 92.84%.
[0038] Obviously, many modifications and variations of the present
invention are possible in light of the above teachings. It is
therefore to be understood that the claimed invention may be
practiced otherwise than as specifically described. Any reference
to claim elements in the singular, e.g., using the articles "a,"
"an," "the," or "said" is not construed as limiting the element to
the singular.
* * * * *