Photoinitiated polymerization of vinyl ether-based systems

The photoinitiated polymerization of vinyl ether (VE)-based coatings has be en studied by real-time infrared (RTM) spectroscopy. in the presence of dia ryliodonium or triarylsulfonium. photoinitiators, the cationic polymerizati on occurs rapidly upon UV-exposure and continues to proceed upon storage in the dark. Increasing the formulation viscosity by introduction of telechel ic VE oligomers was found to have a strong slowing down effect on the UV-cu ring, because of the reduced mobility of the reactive species. VEs proved t o be very effective monomers to achieve a fast and extensive curing of dicy cloaliphatic epoxides. Similar polymerization profiles have been recorded b y RTIR spectroscopy for the two monomers upon UV-exposure, which argues in favor of a copolymerization process between VEs and epoxides. When associat ed to electron acceptor monomers, like unsaturated esters or N-substituted maleimides, VEs undergo a radical-type copolymerization upon UV-exposure. F or the maleate/VE combination, the two monomers were found to disappear at the same rate, whatever the monomer feed composition. The resulting alterna ting copolymer was shown to be formed by homopolymerization of a donor/acce ptor complex. A similar conclusion was drawn from the kinetic data obtained for the maleimide/VE combination which polymerizes readily upon UV-exposur e, even in the absence of any added photoinitiator. (C) 2001 Published by E lsevier Science B.V.