Method of preparing polyorganosiloxane with functional groups in the presence of lithium silanolate

Abstract

The invention relates to a method of preparing polyorganosiloxanes containing at least one functional group using a lithium silanolate catalyst. A polyorganosiloxane, having at least one hydroxyl group, is reacted with a polyalkoxysilane having the formula (R)(R)Si(OR)(I), where Ris an alkyl radical, a cycloalkyl radical, or an aryl radical; Ris —(Z)m-(X)n, wherein m=0 or 1, n=1 or 2; Z is a divalent hydrocarbon residue; X is an unsaturated hydrocarbon radical when m=0 and, when m=1, X is chlorine, bromine, iodine, —O—CO—CR═CRR(in which R, Rand Reach represent a hydrogen atom, an alkyl radical and/or a phenyl radical), —R(in which Ris a perfluorinated residue), —NHR(in which Ris a hydrogen atom, an alkyl radical, or a radical-R—NH, wherein Ris Z), or —SH; Ris an alkyl radical; a=0, 1, 2 or 3; b=0 or 1 and a+b=0, 1, 2 or 3, with the additional condition that the sum a+b=3, symbol b cannot be equal to 0. The method is performed in the presence of an effective quantity of a lithium organosilanolate catalyst having formula (R)(R)(OR)SiOLi(II), wherein R, R, R, a and b have the meanings indicated above. The method is performed without the addition of an aliphatic alcohol having the formula ROH to the reaction medium.