Tris(silyl)trifluoromethanesulfonates and their tetrakis(silyl) analogues as potential catalysts in photoinitiated cationic polymerization

UV initiated cationic photo-curing is commonly carried out in the presence of photo-sensitive onium salts as acid generators. The performance of this class of compounds can be improved by addition of a catalyst (acid) precursor (acid amplifier, AA), prone to acid catalyzed decomposition (also in an autocatalytic sequence). “Trisyl” or “tetrakis”-type esters of strong acids were studied as potential candidates for such a photo-curing purpose. (PhMe2Si)(Me3Si)2CSiMe2OSO2CF3 and [(p-MeC6H4O2SO)Me2Si]4C were found to be the most promising systems. They are more compatible with silicone materials than currently used AAs and can be embedded in the cured resin, thus limiting the post-curing evolution of low molecular weight photolytic decomposition products. They can additionally improve thermal stability of the resin.