Mh. Yang et al., ANIONIC-POLYMERIZATION OF METHYL(3,3,3-TRIFLUOROPROPYL)CYCLOTRISILOXANE, Journal of the Chinese Chemical Society, 40(6), 1993, pp. 557-561
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.