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 19F 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.