UV-radiation curing of acrylate/epoxide systems

Interpenetrating polymer networks (IPNs) have been synthetized by light-ind uced cross-linking polymerization of a mixture of acrylate and epoxide mono mers. The consumption of each monomer upon W-irradiation in the presence of radical and cationic-type photoinitiators was monitored in situ by real-ti me infrared spectroscopy. The acrylate monomer was shown to polymerize fast er and more extensively than the epoxy monomer, which was further consumed upon storage of the sample in the dark, due to the living character of cati onic polymerization. Curing experiments carried out in the presence of air and under air diffusion-free conditions indicate that the radical polymeriz ation of the acrylate monomer is hardly affected by the oxygen inhibition e ffect,, while the cationic polymerization of the epoxy monomer is enhanced by the atmosphere humidity. The addition of a photosensitizer, like isoprop ylthioxanthone, was shown to speed up substantially the polymerization of t he epoxide, with formation within seconds of two fully cured IPNs. (C) 2001 Elsevier Science Ltd. All rights reserved.