Recent development in free radical photopolymerization direct and sensitized excitation of maleimides

Abstract

In several recent reports, the efficient photoinitiated polymerization by excited state maleimides have been shown in numerous acceptor/donor pair combinations [1-10] The strong hydrogen abstractability of the excited triplet state MI has also been evaluated in initiation of acrylate polymerization and the importance of available abstractable hydrogens has been verified [11]. The unique feature of maleimides in general is its dual effect of simultaneously acting as a photoinitiator and as a polymerizable monomer. The mechanistic evaluation of the photoexcitation process was accomplished by laser flash quenching studies. Rates of polymerization and degrees of monomer conversion as a function of irradiance were calculated from photo-DSC and Real Time Infrared Spectroscopy (RTIR) measurements.