Photoinitiated cationic polymerization of epoxides

Difunctional epoxy monomers have been polymerized cationically by UV irradi ation in the presence of a triarylsulfonium photoinitiator. The curing proc ess was followed quantitatively by monitoring the disappearance of the epox y group by infrared spectroscopy and the insolubilization and hardening of the resin upon UV exposure. The addition of epoxidized soyabean oil (ESO) t o an aromatic diepoxide was shown to accelerate the crosslinking reaction w ith formation of a tight polymer network. The photoinitiated copolymerizati on of ESO with a cycloaliphatic diepoxide proceeds extensively and leads wi thin seconds to a fully cured insoluble material showing increased hardness , flexibility and scratch resistance. Interpenetrating polymer networks hav e been generated by a short UV-irradiation of blends of acrylate and epoxy monomers. (C) 2001 Society of Chemical Industry.