Some Studies on the Methacrylat e Postpolymerization Irradiated with UV

Abstract

The polymerization of methyl methacrylate (MMA) in the dark after UV irradiation was investigated to elucidate the nature of initiator. It was found that a mixture of dimethylketene (DMK), formaldehyde and 1, 4-dimethoxy-2, 5-dimethylbenzene was obtained photochemically from vapor of MMA exposed to UV light. The resulting mixture induced rapid polymerization of MMA. Furthermore, the presence of tetramethyl-1, 3-cyclobutanedione (TMBO) brought about a considerable reduction in UV irradiation time on the photoinduced polymerization it seems to be the reason that TMBO irradiated with UV light undergoes photolysis rapidly to DMK in a solution. These results suggest that in the presence of UV light, MMA vapor is converted into DMK which can later act as an initiator for the polymerization in the dark.