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US4820783A
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Method for forming new preceramic polymers for SiC and Si3 N4/SiC
Assignee: Massachusetts Institute of Technology
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Filing: 1986-10-03
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Granted: 1989-04-11
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Expires: 2006-10-03
Abstract
Abstract A method of forming preceramic polymers using a organopolysilane of the formula [(RSiH) x (RSi) y ] n , where R is a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbons atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group and n is an integer greater than 1, and reacting it with alkali metal amides or silylamides in catalytic quantities is disclosed. Preferably, the alkali metal amide is a polymeric alkali metal silylamide of the formula [(R 1 SiHNH) a (R 1 SiN) b (R 1 SiHNM) c ] m where a+b+c=I; R 1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group; M is an alkali metal or one-half equivalent of an alkaline earth metal; and n and m are integers greater than I. Novel preceramic polymers formed by this method are also disclosed.
Inventors
- 👤 Dietmar Seyferth
- 👤 Timothy G. Wood
- 👤 Yuan-Fu Yu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:56
CPC Classifications
C; C08; C08L; C08L83/00; C08L83/16; C08G; C08G77/00; C08G77/60
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
196 words
A ceramic material formed by pyrolyzing a physical mixture of polymers of the formulas [(RSiH) x (RSi) y ] n and [(R 1 SiHNH) a (R 1 SiN) b (R 1 SiHNE) c ] m , where x +y=1, n is an integer greater than 1, R is a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkenyl group having 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms; R 1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group, n and m are integers greater than 1, and E is a moiety introduced by reaction of an electrophile, E-X, where X is a halogen, sulfate or sulfonate, with [(R 1 SiNH) a (R 1 SiN) b (R 1 SiNM) c ] m where M is an alkali metal or one-half equivalent of an alkaline earth metal.
Claim 2
Dependent Claim
196 words
A ceramic material formed by pyrolyzing a physical mixture of polymers of the formulas [(RSiH) x (RSi) y ] n and [(R 1 SiHNH) a (R 1 SiN) b (R 1 SiHNE) c ] m , where x +y=1, n is an integer greater than 1, R is a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkenyl group having 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms; R 1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, a tri(lower)alkyl- or di(lower)alkylsilyl group or a di(lower)alkylamino group, n and m are integers greater than 1, and E is a moiety introduced by reaction of an electrophile, E-X, where X is a halogen, sulfate or sulfonate, with [(R 1 SiNH) a (R 1 SiN) b (R 1 SiNM) c ] m where M is an alkali metal or one-half equivalent of an alkaline earth metal.
Claim 3
Independent Claim
239 words
A method for preparing an organosilicon preceramic polymer, wherein the method comprises: (a) generating a polysilylamide in the presence of a organopolysilane of the formula: [(RSiH) x (RSi) y ] n , where x+y=1; R is a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, and n is an integer greater than 1; wherein the polysilylamide is generated by reacting the ammonolysis product of a R 1 SiHX 2 , where R 1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 crbon atoms, a tri(lower)alkyl or di(lower) alkylsilyl group or a di(lower)alkylamino group and X is a halogen, in solution in the presence of a basic catalyst, wherein the basic catalyst is capable of deprotonating the hydrogen from a nitrogen atom adjacent to a silicon atom, to generate the polysilylamide in situ, referred to as the in situ generated polysilylamide: (b) allowing the in situ generated polysilylamide and the organopolysilane sufficient time to react with each other at room temperature; and (c) quenching the mixture with an organic halide or halosilane to produce the organosilicon preceramic polymer.
Claim 4
Independent Claim
239 words
A method for preparing an organosilicon preceramic polymer, wherein the method comprises: (a) generating a polysilylamide in the presence of a organopolysilane of the formula: [(RSiH) x (RSi) y ] n , where x+y=1; R is a lower alkyl group having from 1 to about 6 carbon atoms, a lower alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, and n is an integer greater than 1; wherein the polysilylamide is generated by reacting the ammonolysis product of a R 1 SiHX 2 , where R 1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted alkenyl group having from 2 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 crbon atoms, a tri(lower)alkyl or di(lower) alkylsilyl group or a di(lower)alkylamino group and X is a halogen, in solution in the presence of a basic catalyst, wherein the basic catalyst is capable of deprotonating the hydrogen from a nitrogen atom adjacent to a silicon atom, to generate the polysilylamide in situ, referred to as the in situ generated polysilylamide: (b) allowing the in situ generated polysilylamide and the organopolysilane sufficient time to react with each other at room temperature; and (c) quenching the mixture with an organic halide or halosilane to produce the organosilicon preceramic polymer.
Claim 5
Dependent Claim
24 words
The method of claim 2 wherein the mixture of in situ generated polysilylamide and the organopolysilane of step (b) is then heated at reflux.
Claim 6
Dependent Claim
30 words
The method of claim 1 wherein the organosilicon preceramic polymer is pyrolyzed in an inert atmosphere for a sufficient time and at a sufficient temperature to form a ceramic product.
Claim 7
Dependent Claim
12 words
The method of claim 1 wherein R is the lower alkyl group.
Claim 8
Dependent Claim
11 words
The method of claim 5, wherein R is CH 3 .
Claim 9
Dependent Claim
30 words
The method of claim 5 wherein the organosilicon preceramic polymer is pyrolyzed in an inert atmosphere for a sufficient time and at a sufficient temperature to form a ceramic product.
Claim 10
Dependent Claim
16 words
The method of claim 6 wherein R 1 SiHX 2 is CH 3 SiHCl 2 .
Claim 11
Dependent Claim
21 words
The method of claim 7 wherein the polymer is pyrolyzed in an inert gas to about 1000° C. to 1300° C.
Claim 12
Dependent Claim
14 words
The method of claim 1 wherein the organic halide is a lower alkyl halide.
Claim 13
Dependent Claim
14 words
The method of claim 10 wherein the lower alkyl halide is CH 3 I.
Claim 14
Dependent Claim
10 words
A preceramic polymer formed by the method of claim 1.
Claim 15
Dependent Claim
10 words
A preceramic polymer formed by the method of claim 10.
Claim 16
Dependent Claim
10 words
A preceramic polymer formed by the method of claim 12.
Claim 17
Dependent Claim
24 words
The ceramic material of claim 1 wherein E is introduced by an electophile selected from the group consisting of lower alkyl halides and halosilanes.
Claim 18
Dependent Claim
13 words
The ceramic material of claim 15 where the electrophile is CH 3 I.
Claim 19
Dependent Claim
18 words
The ceramic polymer of claim 1 where R and R 1 are each independently a lower alkyl group.
Claim 20
Dependent Claim
15 words
The ceramic polymer of claim 17 where R and R 1 are CH 3 .
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