Solvent effects on stereoregularity of poly(vinyl trifluoroacetate) obtained by radical polymerization

Vinyl trifluoroacetate was polymerized by free radicals in various kinds of solvents at temperatures between +60 and ‐40°C. The syndiotactic and isotactic diad contents of the polymer were determined via the triad content, which was obtained by their NMR‐spectra. The differences of the activation enthalpies and those of the activation entropies between isotactic and syndiotactic arrangements were calculated from the temperature dependence of the ratio of isotactic to syndiotactic diads formed in the different solvents. A compensation effect exists between the two differences. The syndiotacticities of the polymers synthesized in alkanes in which the polymers were insoluble were higher than those in esters and ketones in which the polymers were soluble. The syndiotactic diad contents of the polymer synthesized in alkanes and ketones at −40°C amount to 60∼63% and 52∼56% respectively.