Photo-crosslinking of polystyrenes having pendant epoxy groups

Vinylbenzyl glycidyl ether (VBGE), vinylbenzyl 2-methylglycidyl ether (VBMGE), vinylphenethyloxirane (VPO), 2-methyl-2-vinylphenethyloxirane (MVPO) and vinylbenzyl 3,4-epoxycyclohexylmethyl ether (VBECE) were prepared as styrene-type monomers having various pendant epoxides and polymerized by the use of AIBN to afford the corresponding polymers and copolymers with styrene (St). Poly[[2-(3,4-epoxycyclohexyl)ethyl]dimethyl-4-vinylbenzylsilane] (poly(EMVBS)) and poly(EMVBS- co-St) having silicon atoms in pendant groups were synthesized by the hydrosilation of poly(dimethyl-4-vinylbenzylsilane) (poly(MVBS)) and poly(MVBS- co-St), respectively, with 4-vinyl-1-cyclohexene 1,2-epoxide in the presence of catalytic amount of RhCl(PPh 3) 3. Poly[[4-oxa-5-(3,4-epoxycyclohexyl)pentyl]dimethyl-4-vinylbenzylsilane- co-styrene] (poly(OEMVBS- co-St)) containing ether linkage between silicon and epoxy group was also prepared by the hydrosilation of poly(MVBS- co-St) with allyl 3,4-epoxycyclohexylmethyl ether. The obtained polymers were casted with photo-acid generator, irradiated by UV light and the degree of insolubilization of the resulting films was examined. Polymers having cyclohexene oxide unit connected to aromatic ring by –SiCH 2CH 2–linkage (poly(EMVBS) and poly(EMVBS- co-St)) showed highest crosslinking reactivity, while poly(VBECE) and poly(VBECE- co-St) containing cyclohexene oxide unit and ether linkage in pendant group showed lowest. Polymers having 2-methylglycidyl structure at pendant group had higher crosslinking reactivity than those containing the corresponding glycidyl structure. Ether linkage between epoxy group and aromatic ring lowered the reactivity of the epoxide compared to the polymers without such linkage.