Visible-light photopolymerization of DGEBA promoted by silsesquioxanes functionalized with cycloaliphatic epoxy groups

DELL'ERBA IGNACIO; ARENAS GUSTAVO F.; SCHROEDER WALTER F.

POLYMER

ELSEVIER SCI LTD

Lugar: Amsterdam; Año: 2015 vol. 83 p. 172 - 181

0032-3861

Diglycidyl ether of bisphenol A (DGEBA) is among the most popular and widely used epoxy monomers. This monomer is commonly used in thermal network polymerizations with amines, phenols, isocyanatesor mercaptans as curing agents. However, the photoinitiated polymerization of DGEBA is very sluggishand hence finds little use in high-speed photocuring applications. In this contribution, we demonstratedthat this monomer can undergo very fast visible-light photopolymerization when combined with asilsesquioxane (SSO) functionalized with reactive epoxycyclohexane groups. The SSO was synthesized viaalkoxysilane hydrolysis/condensation chemistry, using DGEBA as a solvent. We found that the photopolymerization of DGEBA is markedly accelerated as the amount of SSO in the mixture is increased. The promoter effect on the reactivity of DGEBA was ascribed to a combination of both thermal and copolymerization effects. Using dynamic mechanical analysis, we demonstrated that the resulting hybridmaterials present a single-phase network structure, where the SSO species function as highly multifunctionalepoxy reactants.