Anionic Ring-Opening Copolymerization of Bicyclic Bis(.gamma.-lactone)s with Mono- and Bifunctional Epoxides via Double Ring-Opening Isomerization of the Bis(.gamma.-lactone)s and Volume Change during Copolymerization

Abstract

The first anionic polymerization with small volume shrinkage is described. Volume change in anionic copolymerization of bicyclic bis(γ-lactone) 1c and glycidyl phenyl ether (2) with tBuOK (4 mol %) at 120°C was nearly zero (small expansion, +0.25±0.15%). The anionic copolymerization of aromatic substituent-containing bicyclic bis(γ-lactone)s (1e-g) with 2 was carried out at 120°C in THF and in bulk for 72 h in the presence of tBuOK (4 mol %). The 1 H NMR, 13 C NMR, and IR spectra of the methanol-insoluble parts clearly suggested the proposed alternating copolymer structures consisting of two successive units derived from 1e-g and 2. The anionic copolymerizations of bicyclic bis(γ-lactone)s (1a-g) with equimolar amounts of bifunctional epoxides (5a,b) in bulk were carried out at 120-160°C in the presence of tBuOK (4 mol%) to afford the corresponding dichloromethane-insoluble copolymers (6aa-gb) in quantitative yields. The copolymer composition was ca. 1:0.5 in any case, as estimated from the 1 H NMR spectra of the dichloromethane-soluble parts. Yield of the copolymers decreased when the monomer feed ratio was deviated from 1:0.5. The IR spectral analysis of 6aa-gb strongly suggested the occurrence of the efficient alternating copolymerization. Small shrinkages or expansions in volume (-2.5±0.15% to +2.4±0.15%) were observed during the copolymerizations of 1 and 5, definitely indicating the possibility of 1 as expanding monomers. Thermal properties such as glass transition and 10% weight loss temperatures of the obtained copolymers were evaluated by DSC and TGA