ANIONIC-POLYMERIZATION OF METHYL(3,3,3-TRIFLUOROPROPYL)CYCLOTRISILOXANE

Methods based on anionic ring-opening polymerization, using n-butyl li thium as an initiator, were developed to prepare monodispersed (MwBAR/ MnBAR < 1.2) poly[methyl(3,3,3-trifluoropropyl)siloxane] (PMFPS) from methyl(3,3,3-trifluoropropyl)cyclotrisiloxane (F3) 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 absolu te molecular weight (Mw) of each monodispersed PMFPS was determined by means of universal calibration with GPC/DV (coupled differential visc ometry-GPC) technique. Factors that affect the narrowly distributed li nearly extended polymer chain, such as solvent, temperature, promoter, monomer concentration etc., were discussed in terms of molecular weig ht, molecular weight distribution, polymer conversion and the cyclic o ligomer content through GPC and GC analyses. Back-biting occurred eith er in the bulk or the solution process. However, the presence of a pro moter (DMSO or THF) in a proper proportion accelerated the polymerizat ion, and the reaction went to completion in either process before seri ous backbiting and chain transfer occurred.