Massachusetts Institute of Technology

Yuan-Fu Yu

Dietmar Seyferth

Timothy Grant Wood

Joanne M Schwark

Tom S Targos

Gudrun E Koppetsch

A method of forming preceramic polymers using a organopolysilane of the formula [(RSiH).sub.x (RSi).sub.y ].sub.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.sup.1 SiHNH).sub.a (R.sup.1 SiN).sub.b (R.sup.1 SiHNM).sub.c ].sub.m where a+b+c=I; R.sup.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.

Method for forming new preceramic polymers for SiC and Si.sub.3 N4/SiC

A method of forming preceramic polymers using an organosilicon polymer containing Si--H repeat units by reacting it with alkali metal amide or silylamide is disclosed. Preferably, the silylamide is a polymeric silylamide formed by reacting in solution anhydrous ammonia with a mixture of R.sup.1 SiHX.sub.2 (where R.sup.1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms; and X is a halogen) and R.sup.2 SiX.sub.3 (where R.sup.2 is H, a lower alkenyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower alkenyl group having from 2 to about 6 carbon atoms or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms). The Si--H containing organosilicon polymer is preferably selected from the group consisting of organopolysilanes of the formula [(RSiH).sub.x (RSi).sub.y ].sub.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, or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, and n is greater than 1), a polycarbosilane having repeat units of the formula [R.sup.a Si(H)--(CH.sub.2).sub.q ] (where R.sup.a is H, a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 to about 6 carbon atoms, or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, q is an integer 1 or greater), and a polysiloxane having repeat units of the formula [R.sup.b Si(H)O].sub.n (where R.sup.b is a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 to about 6 carbon atoms, or a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, and n is an integer greater than 1). Novel preceramic polymers formed by this method are also disclosed.

Method for converting organosilicon polymers containing SIH repeat units

A method of forming preceramic polymers by mixing (A) an organic polysilane, preferably either a methylpolysilane of the formula [(RSiH).sub.x (RSi).sub.y ].sub.n, (where R is a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 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 x+y=1, (x and y are each &gt;0 and also x=1, y=0), and n is an integer greater than 1) or a polycarbosilane having repeat units of the formula [R.sup.a Si(H)--(CH.sub.2).sub.q ], [R.sup.a Si(H)--CH.dbd.CH], and [R.sup.a Si(H)--C.tbd.C] (where R.sup.a is H, a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, q is an integer 1 or greater), with (B) an organic or organisilicon compound having at least two alkenyl groups and allowing the mixture to react is disclosed. Preferably, the alkenyl group is a vinyl group. The reaction is preferably initiated by the generation of reactive free radicals. Novel preceramic polymers formed by this method are also disclosed.

Method for forming new preceramic polymers containing silicon

A method of forming preceramic polymers using a polysiloxane having repeat units of the formula [RSi(H)O].sub.n (where R is a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbon atoms, n is an integer 1 or greater), by reacting it with a (poly)silylamide is disclosed. Preferably, the poly(silylamide) is a polymeric alkali metal silylamide of the formula [(R.sup.1 SiHNH).sub.a (R.sup.1 SiN).sub.b (R.sup.1 SiHNM).sub.c ].sub.m where a+b+c=1; R.sup.1 is a lower alkyl group having from 1 to about 6 carbon atoms, a substituted or unsubstituted cycloalkyl group having from 2 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 m is an integer greater than 1. Preferably, a weight ratio of polysiloxane:silylamide of 15:1 to 1:15 is used. Novel preceramic polymers formed by this method are also disclosed.

Method for converting Si-H containing polysiloxanes to new and useful

A method of forming preceramic polymers using a polycarbosilane having repeat units of the formula [RSi(H)--(CH.sub.2).sub.q ] (where R is H, a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 to about 6 carbon atoms, a substituted or unsubstituted lower aryl group having from 6 to about 10 carbons atoms, q is an integer 1 or greater), by reacting it with alkali metal silylamides in a weight ratio of polycarbosilane:silylamide of 10:1 or less is disclosed. Preferably, the alkali metal silylamide is a polymeric alkali metal silylamide of the formula [(R.sup.1 SiHNH).sub.a (R.sup.1 SiN).sub.b (R.sup.1 SiHNM).sub.c ].sub.m where a+b+c=1; R.sup.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 1. Novel preceramic polymers formed by this method are also disclosed.

Method for converting Si-H containing polycarbosilanes to new and useful

A method of forming preceramic polymers using a organopolysilane of the formula [(RSiH).sub.x (RSi).sub.y ].sub.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.sup.1 SiHNH).sub.a (R.sup.1 SiN).sub.b (R.sup.1 SiHNM).sub.c ].sub.m where a+b+c=1; R.sup.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 1. Novel preceramic polymers formed by this method are also disclosed.

Method for forming new preceramic polymers for SiC and Si.sub.3 N.sub.4

A method of forming preceramic polymers by mixing (A) a methylpolysilane of the formula [(RSiH).sub.x (RSi).sub.y ].sub.n, (where R is a lower alkyl group having from 1 to about 6 carbon atoms, a cycloalkyl group having from 3 about to 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 x+y=1, (x and y are each &gt;0 and also x=l, y=o), and n is an integer greater than 1 with (B) an organic or organisilicon compound having at least two alkenyl groups and allowing the mixture to react is disclosed. Preferably, the alkenyl group is a vinyl group. The reaction is preferably initiated by the generation of reactive free radicals. Novel preceramic polymers formed by this method are also disclosed.

Growing community of inventors

Dayton, OH, United States of America

Yuan-Fu Yu