NOVEL BENZYL SULFONIUM SALT HAVING AN AROMATIC GROUP ON SULFUR ATOM AS A LATENT THERMAL INITIATOR

Three benzyl p-hydroxyphenyl methylsulfonium salts with different counter anions were synthesized as novel latent thermal initiators. Syntheses of the sulfonium salts (2) were performed by the reaction of p-hydroxyphenyl methyl sulfide with benzyl chloride followed by exchange of the counter anion (Cl-) with SbF6- (2a), PF6- (2b), or BF4- (2c). In the bulk polymerization of glycidyl phenyl ether (PGE) with 2, initiator activity of the sulfonium salts was evaluated by comparison with that of benzyl tetramethylenesulfonium hexafluoroantimonate (1, R = H). Among the initiators, 2a showed the highest activity, and was much more active than 1 (R = H). Since the polymerization of PGE with 2a proceeded efficiently at more than 80-degrees-C but not at all at less than 60-degrees-C, 2a was suggested to be a good latent thermal initiator.