Solvent effects on the stereochemistry of free radical polymerization of vinyl acetate (VAc) and vinyl pivalate (VPi) were investigated. In the polymerization of VAc, an alcoholic solvent with a smaller pK(a) and higher bulkiness afforded a polymer having a higher syndiotacticity. The polymerization of VAc in perfluoro-tert-butyl alcohol ((CF3)(3)COH) at -78 degrees C led to a diad syndiotacticity r of 72%, which is the highest for the radical polymerization of vinyl esters. On the other hand, the polymerization of VPi in fluoroalcohol at a low temperature afforded a polymer rich in heterotacticity (up to mr = 61%). Synthesis of a heterotactic homopolymer by the free radical polymerization of monosubstituted vinyl monomers is unprecedented. The stereochemical effects observed in this study may be due to hydrogen-bond interaction between the fluoroalcohol molecules and the ester groups of the vinyl ester monomer and the side chain of the growing polymer, Mechanisms of stereoregulation were proposed.