Photocrosslinking of polymethoxymethylstyrene and copolymers containing (2,2-disubstituted-1,3-dioxolan-4-yl)methoxymethylstyrene

Methoxymethylstyrene (MSt), (2,2-dimethyl-1,3-dioxolan-4-yl)methoxymethylstyrene (MMSt), and (2-ethyl-2-methyl-1,3-dioxolan-4-yl)methoxymethylstyrene (EMSt) were synthesized and homopolymerized and copolymerized. The photochemical behavior of resultant homopolymers and copolymers with methyl methacrylate (MMA) and styrene (St) were investigated. The infrared (IR) and ultraviolet (UV) spectra of poly(MSt) showed that new bands ascribed to methyl benzoate residue increase rapidly with irrdiation time in air, but no detectable changes are observed in vacuum. The solubility measurements of poly(MSt) indicate that the main factor in crosslinking is the direct coupling of the benzyl radical generated by UV irradiation, which was confirmed by photopolymerization of MMA by means of benzyl methyl ether. It was also found that copolymers of MMSt or EMSt with MMA or St are easily crosslinked by UV irradiation. From the results of solubility measurements of these copolymers irradiated both in air and in vaccum, it was concluded that not only the 1,3-dioxolane structure but also the benzyl methyl ether structure takes part in photocrosslinking, as we expected.