Carbon black-supported sulfuric acid or BF3. Et2O-initiated polymerizations of 2-methylene-4,4,5,5-tetramethyl-1,3-dioxlane (1), 2-methylene-4-phenyl-1,3-dioxolane (2), and 2-methylene-4-isopropyl-5,5-dimethyl-1,3-dioxane (3) were performed. 1,2-Vinyl addition homopolymers of 1-3 were produced using carbon black-supported H2SO4 initiation at temperatures from 0 degrees C to 60 degrees C whereas both ring-opened and 1,2-vinyl structural units were present in the polymers using BF3. Et2O as an initiator. Cationic polymerizations of 2-methylene-1,3-dithiolane (4) and copolymerization of 4 with 2-methylene-4-(t-butyl)-1,3-dioxolane (5) were initiated with either carbon black-sulfuric acid or BF3. Et2O. Insoluble 1,a-vinyl addition homopolymers of 4 were obtained upon initiation with the supported acid or BF3. Et2O. A soluble copolymer of 2-methylene-1,3-dithiolane (4) and 4-(t-butyl)-2-methylene-1,3-dioxolane (5) was obtained upon BF3. Et2O initiation. This copolymer is composed of three structural units: a ring-opened dithioester unit, a 1,2-vinyl polymerized 1,3-dithiolane unit, and a 1,2-vinyl polymerized 4-(t-butyl)-1,3-dioxolane unit.