Cationic Polymerizability of Vinyl Acetate: Alternating Copolymerization with 1,3-Dioxolan-4-ones and Branched Copolymer Formation with Cyclic Acetals

Abstract

Vinyl acetate (VAc) potentially exhibits cationic polymerizability due to electron donation from the oxygen atom adjacent to the vinyl group through resonance. In this study, cationic copolymerizations of VAc and comonomers with little or no homopolymerizability were shown to proceed with very frequent crossover reactions. Alternating copolymers were produced when 1,3-dioxolan-4-ones, which generate a carbocation adjacent to oxygen via ring opening and exhibit no homopolymerizability, were used as comonomers in copolymerizations with VAc catalyzed by GaCl 3 . An alternating copolymer with an M n of 6.4 × 10 3 was obtained in the copolymerization of VAc and 2,5-dimethyl-1,3-dioxolan-4-one. Moreover, branched copolymers containing a portion with molecular weights over 10 5 were generated in copolymerizations of VAc with cyclic acetals exhibiting appropriate structures. Specifically, abstraction of the VAc-derived acetoxy group from the hemiacetal ester moiety in the main chain most likely resulted in carbocation generation and subsequent reaction with a monomer to form branched structures. The reaction of a hemiacetal ester moiety did not occur likely due to the rigid cyclic structure when α-angelicalactone was used instead of VAc, resulting in an alternating copolymer with an M n of 10.4 × 10 3 in the copolymerization with 1,3-dioxane. The copolymerization mechanisms generating such copolymer structures were discussed based on detailed analyses of the polymerization products by NMR spectroscopy.

Recent Advances in Sequence‐Controlled Ring‐Opening Copolymerizations of Monomer Mixtures

“…However, vinyl acetates could copolymerize with 1,3-dioxolan-4-ones to form alternating polyesters with M n s ~6.4 kDa and Đs ~3 at À 40 °C using Lewis acid GaCl 3 . [131] Nevertheless, vinyl acetates had low monomer conversions < 30%, which resulted in low-MW copolymers. (Scheme 6e) 2.5.…”

“…Vinyl acetates are usually inert in cationic polymerization due to the inefficient generation of carbocations. However, vinyl acetates could copolymerize with 1,3‐dioxolan‐4‐ones to form alternating polyesters with M n s∼6.4 kDa and Đ s∼3 at −40 °C using Lewis acid GaCl 3 [131] . Nevertheless, vinyl acetates had low monomer conversions <30%, which resulted in low‐MW copolymers.…”

Ring‐Opening Polymerization of Cyclic Acetals: Strategy for both Recyclable and Degradable Materials

“…Vinyl esters were also able to copolymerize with cyclic acetals using GaCl 3 as a catalyst (copolymer (4) in Scheme 10, entries 25–35 in Table 4). [ 60 ] Branched copolymers containing hemiacetal ester groups were generated in copolymerizations of vinyl acetate (VAc) with DO or DOX. These copolymers were more labile than those with acetal moieties.…”

“…However, the work is lacking convincing evidence to prove the existence of acetal groups in the copolymer backbone. Copolymerization of VAc with substituted 1,3‐dioxolan‐4‐one using GaCl 3 as the catalyst was also achieved, [ 60 ] among which 5‐methyl‐1,3‐dioxolan‐4‐one and 2,5‐dimethyl‐1,3‐dioxolan‐4‐one ( EA2 ) afforded alternating copolymers. Hillmyer et al .…”

“…Another six-membered cyclic acetal 1,3-dioxane (DOX) was reported to be non-homo-polymerizable. [60] Limited research on DOX revealed the copolymerization of DOX with DO and tetrahydrofuran (THF). [61][62][63] The T c was determined to be −70 °C on the basis of the copolymerization data.…”