The effect of substituents on the catalytic activity of benzylpyridinium salts and their application to non-solvent type thermosetting compositions (in English)
Polimery 1998, No 11-12, 679
Latent thermal initiators, 1-(4-substituted benzyl)-4-cyanopyridinium SbF6- (I) and 1-( α, α-dimethylbenzyl)-4-substituted pyridinium SbF6- (II), were synthesized and their catalytic activities were evaluated in cationic polymerization of glycidyl phenyl ether (GPE). Compounds I initiated cationic polymerization of GPE above 120°C, and their catalytic activity increased in the following order of 4-substituents: H < Me = t-Bu < Cl < MeO. On the other hand, compounds II polymerized GPE cationically above 65°C, and their catalytic activity increased depending on the electron withdrawing effect of the 4-substituents in the order: Me < H < Cl < CN. Compounds II were able to polymerize GPE at temperatures by 100°C lower than those of compounds I, with the same leaving group. Non-solvent type thermosetting compositions consisting of compound II and bisphenol A diglycidyl ether were formulated to evaluate curability and storage stability. Crosslinking reaction of these thermosetting compositions proceeded smoothly via cationic polymerization to produce cured films with gel fractions higher than 90%. Furthermore, these compositions showed good storage stability at 40°C. Consequently, compounds II may provide non-solvent type thermosetting compositions in combination with bisphenol A diglycidyl ether.
Keywords: cationic polymerization, benzylpyridinium salts, cationic initiators, thermal latency, latent catalysts, bisphenol A diglycidyl ether