Novel materials based on silicone–acrylate copolymer networks

Abstract

This article presents a broad class of materials made by copolymerization of a family of telechelic free radically polymerizable siloxanes with various acrylate monomers that polymerize to form high Tg polymers. Films with properties ranging from strong elastomers to plastics have been obtained by UV-initiated bulk copolymerization of functional siloxanes dissolved in acrylate monomers (in the presence of a photoinitiator). The molecular weight of the functional siloxanes, the nature of functional endgroups, the choice of (meth)acrylate comonomer, and the siloxane/acrylate ratio all have a rather dramatic effect on the morphology, and thus, on the properties of the copolymeric networks. Physical properties of the materials, such as optical appearance and mechanical and transport properties are correlated with the unique morphologies observed by TEM studies. Unusual properties such as reversible whitening of some of the materials and low Poisson ratios have been attributed to the microcavitation observed when high Tg acrylate domains interfere with the network deformation. Networks composed of high Tg acrylates (major fraction) coreacted with elastomeric siloxanes can provide heat-shrinkable materials when they are elongated at temperatures higher than the Tg of the corresponding polyacrylates and quenched. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 159–180, 2001