Porous Silicon Used as an Initiator in Polymerization Reactions

Abstract

ABSTRACTPorous silicon is investigated as an initiator for radical polymerization reactions. Surface radicals and photogenerated e−/h+ pairs in porous silicon can be used to initiate polymerization reactions. Porous silicon wafers were placed in ethanolic solutions of methyl methacrylate, N-vinylcarbazole, acrylonitrile, or styrene and either left in the dark or excited by light. Methyl methacrylate polymerized in the absence of light, presumably via silicon-based radical initiator sites at the porous silicon surface. The N-vinylcarbazole polymerized to a small extent in the dark, and to a much greater extent during white light irradiation of the porous silicon surface. Photopolymerization is thought to occur via excited state hole transfer from the porous silicon to the N-vinylcarbazole monomer. Very little to no polymerization of acrylonitrile or styrene could be detected either in the dark or under illumination.