Effect of acidity on acid-sensitive UV curing system

By using diphenyliodonium salts with different counterions as photo acid ge nerators (PAGs), the effect of acidity on ring-opening polymerization of ep oxy monomers and polycondensation of polyol with hexamethoxymethyl melamine (HMMM) was studied. The result shows that the rate of ring-opening polymer ization is evidently dependent on the acidity of the acid and strong photo- generated acid is required. However, there is a leveling effect in the poly condensation system; if the photo-generated acid is stronger than protonate d HMMM, the acidity does not obviously affect the polycondensation rate.