Interpenetrating polymer networks based on polyurethane and epoxy based polymer containing phenylazo benzothiazole (BT) chromophore groups were synthesized.Crosslinked polyurethane was obtained by the reaction between (2 hydroxypropyl acrylate BT 2 methacrylate) copolymer and phenol capped NCO terminated BT 1

whereas crosslinked epoxybased polymer was formed by reaction between epoxy containing BT and BT containing aniline.The IPNs were synthesized by carrying out the above two reactions simultaneously

and were characterized by gel content

IR spectra and differential scanning calorimertry.The IPN shows two Tg at 142℃ and 170 ℃.Thin

transparent poled films of the IPN were prepared by spin-coating

followed by thermal curing and corona poling at 160℃ for 1h.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.Long-term stability of the dipole alignment at 120℃ was demonstrated for the IPN.