ANIONIC CROSS-LINKING OF POLYMERS HAVING AN EPOXY GROUP IN THE SIDE-CHAIN WITH BICYCLIC AND SPIROCYCLIC BIS(GAMMA-LACTONE)S

Anionic cross-linkings of epoxy group containing polymers such as poly (glycidyl methacrylate) (6) and poly(4-(glycidylmethyl)styrene) (7) wi th bicyclic acid spirocyclic bis(gamma-lactone)s (1-3) are described. A model study using glycidyl pivalate (8) as the polymer model compoun d was carried out at 120 degrees C in THF ([C] = 4.0 M) in the presenc e of potassium tert-butoxide (2 mol %) to obtain the corresponding alt ernating copolymers (9-11) in 62-69% yields. The anionic cross-linking s of 6 and 7 with 1-3 and homopolymerizations of 6 and 7 under similar conditions afforded dichloromethane-insoluble cross-linked (co)polyme rs (12-19) quantitatively. The IR spectral change might suggest strong ly that the cross-linked copolymers formed had polyester group consist ing of an almost completely alternating copolymer unit. Recovery of a small amount of 1-3 would suggest that the polyester side chain contai ned a small amount of a polyether unit in some cases. The degree of ri ng-opening of epoxy group of 6 and 7 was 100% in most cases. Homopolym erizations of 6 and 7 were accompanied by 5.4% and 6.3% volume shrinka ge, respectively, although the degree of ring-opening of tile epoxy gr oup was very low (27% and 38%). Volume shrinkage (2.5-5.4%) observed i n the cross-linkings of 6 and 7 with 1-3 was relatively lower in spite that tile degree Of ring-opening of epoxy group was 100%. It was conc luded that volume shrinkage during cross-linking of epoxy group contai ning polymers can be considerably suppressed by addition of 1-3 as an additive. Thermal properties such as glass transition and 10% weight l oss temperatures of the crosslinked polymers 12-19 obtained were evalu ated by DSC and TGA.