A free-volume model for photopolymerizable/cross-linkable dry-film systems, Michel F. Molaire

Journal of Polymer Science: Polymer Chemistry Edition

Volume 20, Issue 3, pages 847–861, March 1982

Abstract

A photopolymerizable/cross-linkable dry-film system is generally a compatible mixture of three main ingredients: a preformed polymeric binder, a multifunctional polymerizable monomer, and a photoinitiating system. The photographic speed of systems sensitized with certain free-radical sensitizers which undergo intermolecular hydrogen-abstraction (e.g., benzophenone/Michler's ketone) is proportional to the excess fractional free volume (VfVfg), of the dry coating. Free-volume dependence appears to be determined by the molecular size or configuration of the actual initiating species. We used as a working model the copolymer system poly[4,4′-isopropylidenediphenylene-1,1,3-trimethyl-3-phenylindan-5,4′-dicarboxylate:azelate] and tri(6-acryloyloxyhexyl)-1,3,5-benzenetricarboxylate as the polymerizable/cross-linkable monomer. A mathematical model based on experimental data and the free-volume theory was developed. The photographic speed of a photopolymerizable/cross-linkable dry-film system suffering from free-volume dependence can be correlated with the glass transition temperatures of the polymeric binder and the monomer, the volume fraction of the monomer, and the temperature of exposure