Polysiloxane(s) with silane gp. at one end and another gp. at the other - by anionic polymerisation of hexa:methyl:cyclo:tri:siloxane with lithium alcoholate, and addn of a functional silane chain-stopper

摘要

The organopolysiloxanes are of formula (I) wherein R1-R3 = 1-4C alkyl or aryl; R4 = OR5 (with R5 = 1-4C alkyl) or aryl, or a gp. of formula -CH2CH2-Phe-CH2Cl, -(CH2)10COOMe, -CH2CH2-(3,4-epoxycyclohexyl), -(CH2)3-O-glycidyl or -(CH2)mR6 (with Phe = 1,4-phenylene; R6 = OH, NH2 or Cl, opt. with H atom(s) in OH and NH2 replaced by SiMe3; m = 1-10); a = 6-100; b = 0 or 1; and c = 0 or 1. Also claimed is a process for the prodn. of (I), comprising (1) cleavage of tetramethylcyclotetrasiloxane (TMCT) with organo-lithium cpds. R1Li to give Li silonalates of formula HSiR1Me-OLi (II), (2) anionic polymerisation of hexamethylcyclotrisiloxane (HMCT) with (II), (3) stopping polymerisation with cpds. of formula XSiR2bR3cR43-(b+c) (III) (with X = Cl, Br or acyloxy) and opt. (4) cleavage of Me3Si gps. by alcoholysis or hydrolysis. USE/ADVANTAGE - There is minimal formation of by-prods. (I) are useful for the prodn. of siloxane copolymers with predetermined structures.