Photo Acid Generator for Cationic Polymerization

During photo-curing with epoxy monomers and others, photo-cationic polymerization is preferred due to its several advantages over photo-radical polymerization. Bis[4-(tert-butyl)phenyl]iodonium tetra(perfluoro-tert-butoxy)aluminate is a photo acid generator (PAG) with an aluminate anion, one of weakly coordinating anions (WCAs) with low nucleophilicity.¹⁾ The aluminate anion induced by light allows cationic polymerization to proceed like other WCAs such as hexafluoroantimonate, tris(trifluoromethanesulfonyl)methanide and tetrakis[3,5-bis(trifluoromethyl)]borate. It has also been reported that an iodonium salt of the aluminate anion can be applied to radical-induced cationic frontal polymerization (i.e. polymerized by the acid generated by radicals derived from the heat of polymerization).²⁾