The first anionic polymerization with small volume shrinkage is described. Volume change in anionic copolymerization of bicyclic bis(y-lactone) lc and glycidyl phenyl ether (2) with potassium teri-butoxide (4 mol %) at 120 °C was nearly zero (small expansion, +0.25 ± 0.15%). The anionic copolymerization of aromatic substituent-containing bicyclic bis(y-lactone)s (le-g) with 2 was carried out at 120 °C in THF and in bulk for 72 h in the presence of potassium ferf-butoxide (4 mol %). The NMR, 13C NMR, and IR spectra of the methanol-insoluble parts clearly suggested the proposed alternating copolymer structures consisting of two successive units derived from le-g and 2. The anionic copolymerizations of bicyclic bis(y-lactone)s (la-g) with equimolar amounts of bifunctional epoxides (5a,b) in bulk were carried out at 120-160 °C in the presence of potassium ieri-butoxide (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 NMR spectra of the dichlorometbanesoluble 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.

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Anionic cross-linkings of epoxy group containing polymers such as poly(glycidyl methacrylate) (6) and poly(4-(glycidylmethyl)styrene) (7) with bicyclic and spirocyclic bis(γ-lactone)s (1−3) are described. A model study using glycidyl pivalate (8) as the polymer model compound was carried out at 120 °C in THF ([C] = 4.0 M) in the presence of potassium tert-butoxide (2 mol %) to obtain the corresponding alternating copolymers (9−11) in 62−69% yields. The anionic cross-linkings of 6 and 7 with 1−3 and homopolymerizations of 6 and 7 under similar conditions afforded dichloromethane-insoluble cross-linked (co)polymers (12−19) quantitatively. The IR spectral change might suggest strongly that the cross-linked copolymers formed had polyester group consisting of an almost completely alternating copolymer unit. Recovery of a small amount of 1−3 would suggest that the polyester side chain contained a small amount of a polyether unit in some cases. The degree of ring-opening of epoxy group of 6 and 7 was 100% in most cases. Homopolymerizations of 6 and 7 were accompanied by 5.4% and 6.3% volume shrinkage, respectively, although the degree of ring-opening of the epoxy group was very low (27% and 38%). Volume shrinkage (2.5−5.4%) observed in the cross-linkings of 6 and 7 with 1−3 was relatively lower in spite that the degree of ring-opening of epoxy group was 100%. It was concluded that volume shrinkage during cross-linking of epoxy group containing polymers can be considerably suppressed by addition of 1−3 as an additive. Thermal properties such as glass transition and 10% weight loss temperatures of the cross-linked polymers 12−19 obtained were evaluated by DSC and TGA.

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