Process for making siloxane compositions

摘要

A process for making a dispersion of a high viscosity siloxane in a volatile cyclosiloxane comprises the step of effecting ring-opening polymerisation of a volatile cyclosiloxane under catalysis by a phosphazene base, and the step of stopping the polymerisation reaction before completion of the ring-opening polymerisation of the cyclosiloxane has occurred. Preferably the polymerisation reaction is stopped by adding carbon dioxide or an acid.