Synthesis and properties of two kinds of nonlinear optical interpenetrating polymer networks

Abstract

Two kinds of interpenetrating polymer networks (IPNs) containing 4-(4'-nitrophenylazo)aniline chromophore groups were synthesized. A polyacrylate network was prepared by polymerization of Dispersed Red-19 (DR-19) diacrylate, whereas an epoxy resin network was formed by reaction of Bisphenol A-type epoxy resin E44 with 4(4'-nitrophenylazo)-3-amino aniline. A polyurethane network was synthesized by reaction between (β-hydroxyl propyl acrylate-DR-1 methacrylate) copolymer and phenol-capped isocynate-terminated DR-19. IPNs based on polyacrylate/epoxy resin and IPNs based on polyurethane/epoxy resin were obtained by carrying out two corresponding kinds of reactions simultaneously. Both kinds of IPNs were characterized by gel content, IR spectra, and DSC. The first kind of IPNs exhibits two glass transition temperatures at 122 and 165°C, while the second kind of IPNs showed one broad glass transition temperature at 172°C. Thin and transparent poled films of both IPNs were prepared by spin-coating, followed by thermal curing and corona poling at 160°C for 1 h. The second-order nonlinear optical properties of the poled films were studied by a visible light absorbance measurement according to the one-dimensional rigid oriented gas model. The polyurethane/epoxy resin IPNs were more stable in dipole alignment than were the polyacrylate/epoxy resin IPNs at temperature higher than 120°C