Polymerisation catalyst and polymerisation process

摘要

Siloxanes are polymerised by equilibration, condensation and/or ring-opening polymerisation using a phosphazene base catalyst. A linear phosphazene base catalyst of the general formula <CHEM> wherein R denotes a C1-10 hydrocarbon or wherein two R groups on one N atom form with the N atom a heterocyclic group, X denotes an anion and n is from 1 to 10 is prepared by reacting a linear phosphonitrile halide compound with a secondary amine or a salt of a secondary amine or a metal amide thereof to form an aminated phosphazene material, followed by an ion exchange reaction replacing the anion with a nucleophile.