METHOD FOR USING ORGANOPOLYSILAZANE PRECURSORS TO FORM NEW PRECERAMIC POLYMERS AND SILICON NITRIDE-RICH CERAMIC MATERIALS

摘要

A method for preparing preceramic polymers. This method includes the steps of (1) reacting in solution anhydrous ammonia with a mixture of R<1>SiHX2 (where R<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 RSiX3 (where R is H, 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 unsubsituted 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), thereby forming a mixture of precursor polymers; and reacting the precursor polymers in the presence of a basic catalyst capable of deprotonating the NH functions in the precursor polymers to form the preceramic polymer. Preferably, this preceramic polymer is treated with an electrophile compound. Pyrolyzing the polymer in an inert gas stream or ammonia atmosphere to form a ceramic material is also disclosed. In a different embodiment the polymeric silylamide which is formed by reacting in solution anhydrous ammonia with a mixture of R<1>SiHX2 (where R<1> and X are as described above) and R<2>SiX3 (where R<2> as described above) can be used to form a different and useful preceramic polymer by reacting it with an organosilicon polymer containing Si-H repeat units. The Si-H containing organosilicon polymer is preferably selected from the group consisting of organopolysilanes 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, 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 [RSi(H)-(CH2)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, 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 [RSi(H)O]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, 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.