Reactivity of mixtures of epoxy monomers in photoinitiated cationic polymerization

WALTER F. SCHROEDER; SILVANA V. ASMUSSEN; GUSTAVO F. ARENAS; IGNACIO E. DELL'ERBA; CLAUDIA I. VALLO

Blacksburg, Virginia

Congreso; World Polymer Congress - Macro 2012; 2012

VirginiaTech y IUPAC (International Union of Pure and Applied Chemistry)

Photoinitiated ring opening polymerization of epoxy monomers has been the subject of extensive studies during the last two decades. Results reported in the literature show that these monomers display different behaviors depending on their molecular structures. Epoxy monomers that bear no means of stabilizing the intermediate oxonium ions proceed rapidly and exothermically on UV irradiation. These monomers are commonly termed ?class I? monomers. In contrast, epoxy monomers (class II) that bear neighboring oxygen atoms in the structure able to stabilize the oxonium ion intermediates undergo photopolymerizations that are characterized by an extended induction period followed by rapid, autoaccelerated polymerization. Alkyl glycidyl ethers are typical monomers that exhibit this behavior. Finally, epoxy monomers that have oxygen atoms that are less affective in stabilizing the oxonium intermediates constitute a third group called ?class III? monomers. Included in this group are aryl glycidyl ethers. These latter monomers undergo slow photoinitiated cationic polymerization without a marked induction period. Most practical applications for cationic photopolymerization are currently limited to class I monomers. In this work we investigate whether the polymerization rate of a class III epoxy monomer can be accelerated by conducting the reaction in the presence of a more reactive, class I epoxy monomer.