Photoinitiator-Free, Open-Air Acceptor/Donor Copolymerization of Bismaleimides: Simple Polymerization Conditions for New Thermoplastic Elastomer Production

A photoinitiator-free acceptor-donor copolymerization between a mixture of bismaleimides containing oligo(propyleneglycol)s as acceptor monomers and divinyl ether as the donor monomer under UV is described. The copolymerization without any photoinitiator is faster than homopolymerization of the sole maleimide, thanks to an acceptor-donor charge-transfer complex. The thermal and mechanical properties of the cured materials depend essentially on the cross-linking densities and on the number of repeated units in the bismaleimide backbone. Most copolymerizations produce elastomers with remarkable rubbery properties on a large temperature scale. The simple chemistry presented here can easily compete with acrylate photochemistry since neither photoinitiator nor oxygen removal is needed.