Dye-sensitized photopolymerization of N,N¢ -methylenebisacrylamide by initiation with eosin–ascorbic acid system

The dye-sensitized photopolymerization of N,N-methylenebisacrylamide (MBA) in aqueous medium initiated by eosin–ascorbic acid (AH2) was studied at 25C. The polymerization takes place only at higher concentration of AH2 (> 10–3 mol/L) and its rate increases rapidly as [AH2] is increased. The rate of polymerization is proportional to [MBA] and [AH2]. Kinetic results indicate that semi-quinone (DH^•) dye radical and semi-oxidized form (A•– ) of ascorbic acid are unable to initiate polymerization. Formation of H2O2 is proposed and confirmed. A suitable mechanism is proposed in accordance with experimental results obtained.