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 ‐F 3 ) 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 19 F 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 ‐F 3 were solid and crystalline at room temperature while the more typical polymers from mixtures of isomers containing greater than 50% trans ‐F 3 were liquid and amorphous.