STEREOREGULARITY IN POLY[METHYL(3,3,3-TRIFLUOROPROPYL)SILOXANE]

Anionic ring-opening polymerization of the cis and trans isomers of 1,3,5-trimethyl-1,3,5-tris(3',3',3'-trifluoropropyl)cyclotrisiloxane (cis- and trans-F3) and their mixtures was conducted under conditions that suppressed siloxane bond redistribution in order to preserve stereoregularity formed in the resulting poly[methyl(3,3,3-trifluoropropyl)siloxane] (PMTFPS). Proton decoupled F-19 NMR of the resulting polymers was interpreted by assuming that the original stereoconfiguration of the monomer was preserved and that the monomer inserted with a roughly equal probability of forming meso or racemic configurations relative to the configuration of the reacting chain end. Polymers from cis-F3 were solid and crystalline at room temperature while the more typical polymers from mixtures of isomers containing greater than 50% trans-F3 were liquid and amorphous.