Synthesis and Properties of Novel Epoxy Resins by Radical Copolymerization of 2-Vinyloxyethyl Glycidyl Ether and N-Phenylmaleimide

To develop an epoxy resin having a high glass transition temperature and heat resistance, copolymerization of an epoxy group-containing vinyl ether and a maleimide derivative was carried out. Radical copolymerization of 2-vinyloxyethylglycidyl ether (VEGE) and N-phenylmaleimide (NPMI) with AIBN were carried out in benzene or THF to give polymers having a molecular weight of 120,000 to 250,000 (in case of benzene) and a molecular weight of about 6,000 (in case of THF) in high yield, respectively. On the other hand, the copolymerization in the absence of AIBN hardly progressed in benzene, but in THF the polymers with a molecular weight of about 5,000 were obtained in high yield. H-1 NMR spectroscopy showed that the structure of the products is a copolymer composed of VEGE units and NPMI units. MALDI-TOF-MS spectroscopy revealed that the VEGE units and NPMI units are arranged mainly in an alternative manner. The glass transition temperature (T-g) of the copolymers greatly varied depending on the copolymer composition and remarkably increased as the content of NPMI units increased. The thermal decomposition temperature (T-d) of the copolymers was about 300 degrees C or higher depending on the content NPMI units. By curing the reactive epoxy groups in the copolymers with multifunctional aromatic amines, novel heat-resistant epoxy cured resins with high T-g were obtained.