Process for producing an organometallic copolymer

Claim 1

A process for producing an organometallic block polymer having a number average molecular weight of about 1000 to about 50000 and composed of a polycarbosilane portion and a polymetallosiloxane portion crosslinked with each other, which comprises mixing (1) polycarbosilane with a number average molecular weight of about 500 to about 10000 having a main chain skeleton composed mainly of carbosilane units of the formula --Si-CH 2 --, each silicon atom of said carbosilane units substantially having bonded thereto a side-chain group selected from the class consisting of hydrogen, lower alkyl and phenyl, with (2) a polymetallosiloxane with a number average molecular weight of about 500 to about 10000 having a main chain skeleton composed of metalloxane units of the formula --M--O-- wherein M represents a metal atom selected from the group consisting of Ti and Zr and siloxane units of the formula --Si--O--, most of the metal atoms M of said metalloxane units having bonded thereto a side-chain group selected from the class consisting of lower alkoxy, phenoxy and acetylacetoxy, most of the silicon atoms of said siloxane units having bonded thereto a side-chain group selected from the class consisting of lower alkyl and phenyl, the ratio of the total number of said metalloxane units to that of said siloxane units being in the range of from about 30:1 to about 1:30 in such proportions that the ratio of the total number of said carbosilane units to the sum of the total number of said metalloxane units and the total number of said siloxane units is in the range of from about 100:1 to about 1:100; and heating the resulting mixture in an organic solvent in an atmosphere inert to the reaction to bond at least some of the silicon atoms of said polycarbosilane to at least some of the metal atoms M and/or silicon atoms of said polymetallosiloxane through an oxygen atom.