Radical Polymerization of Styrene Initiated with Alkyl N,N-Diethyldithiocarbamylacetate Photoiniferters

Radical polymerization of styrene initiated with alkyl N,N-diethyl-dithiocarbamylacetate photoiniferter was studied in which the molecular weight of polymers increases with both reaction time and monomer conversion. A similar result was obtained when photopolymerization of styrene in the presence of polystyrene with the N,N-diethyldithiocarbamyl end group was carried out. The polystyrene with the N,N-diethyl-dithiocarbamyl end group was used as a macroiniferter to polymerize methyl methacrylate and vinyl acetate in the formation of block copolymers. The mechanism of photopolymerization was investigated via spin trapping and the electron paramagnetic resonance technique using 2-methyl-2-nitrosopropane as a trapping agent. The deviation in molecular weight distribution was ascribed to slow initiation and slow exchange between dormant and growing radical species.