Polymeric Foam by Photoinitiated Polymerization of Trimethylolpropanetriacrylate: Initiator and Solvent Effects

Abstract

A comprehensive examination of the preparation of polymeric foam via the photopolymerization of trimethylolpropanetriacrylate, TMPTA, was undertaken. Foam properties such as uniformity, shrinkage, density, microstructure, physical integrity, and machinability were measured as a function of initiator, solvent, and processing conditions. The photopolymerization rate of TMPTA in poly(oxyethylene[4]) lauryl ether, or Brij 30, and glycol ethers is enhanced using active photoinitiators such as benzoinethylether and 2,2-dimethoxy-2-phenylacetophenone. The properties of the TMPTA foams were identical for all photoinitiators examined. The properties of the TMPTA foams were dramatically changed when a co-solvent was employed. The co-solvents were triethyleneglycol dimethyl ether and triethyleneglycol monomethyl ether. The use of co-solvents leads to greater shrinkage and a higher than expected foam density. Unlike foams prepared in Brij 30, foams prepared using glycol ethers possess good physical properties and can be machined into cylinders with a smooth surface finish.