Nonlinear optical polymer films based on sol-gel derived polysilsesquioxane with pendant chromophoric subunits embedded in size-matched pores

Two new hybrid nonlinear optical (NLO) polymeric films have been fabricated from the corresponding monomers, alpha, omega-bis(trimethoxysilyl)-1,4-dip ropoxybenzenes bearing one or two moieties of pendant groups of N-(4)-nitro phenol-(L)-prolinol (NPP) on the spacer respectively by molecular design an d "in-situ poling and sol-gel" process. These films are of enhanced thermal stability, extended temporal stability and higher second harmonic generati on (SHG) susceptibilities. Their d(33) values are 2.0 x 10(-8) esu and 3.2 x 10(-8) esu., respectively. These properties can be ascribed to the molecu le-level embedment of NPP moieties in size-matched pore of the polysilsesqu ioxanes and fixation of the orientation of the poled chromophore given by t he pore formed after the alignment of NPP moieties. The structures and morp hologies of the two polymeric films investigated by XRD, FT-IR, DSC, TGA, A FM, etc. show a close correlation with the SHG properties.