Anionic Polymerization of Methyl(3,3,3‐Trifluoropropyl)cyclotrisiloxane

Abstract

Abstract Methods based on anionic ring‐opening polymerization, using n‐butyl lithium as an initiator, were developed to prepare monodispersed (Mw/Mn < 1.2) poly[methyl(3,3,3‐trifluoropropyl)siloxane] (PMFPS) from methyl(3,3,3‐trifluoropropyl)cyclotrisiloxane (F 3 ) in high yield. The resulting polymers have the molecular weights ranged from 4 k to 190 k (k = 1000). Each polymer was characterized by GPC and DSC. The absolute molecular weight (Mw) of each monodispersed PMFPS was determined by means of universal calibration with GPC/DV (coupled differential viscometry‐GPC) technique. Factors that affect the narrowly distributed linearly extended polymer chain, such as solvent, temperature, promoter, monomer concentration etc., were discussed in terms of molecular weight, molecular weight distribution, polymer conversion and the cyclic oligomer content through GPC and GC analyses. Back‐biting occurred either in the bulk or the solution process. However, the presence of a promoter (DMSO or THF) in a proper proportion accelerated the polymerization, and the reaction went to completion in either process before serious backbiting and chain transfer occurred.