Polymer Electrets with Quadratic Nonlinear-optical Activity

The nonlinear-optical (NLO) activities of composite materials with a binary set of chromophores are measured with the Second Harmonic Generation technique (lambda=1064 nm). In these materials the host matrix is an epoxy amine polymer with an azochromophore, covalently attached in such a way that its donor-group is included in the main chain. Apart from this chromophore functionalized epoxy amine oligomer, CFAO, a guest azochromophore dispersed orange, DO3, is added. The addition of DO3 in two concentrations (10 and 20 wt%) enhances the NLO coefficient compared to that for CFAO by ca. 40%. Molecular modeling in an amorphous cell is used for estimating the local mobility of different groups and fragments of the polymeric chain, in particular, that of the azochromophores. The information obtained from the modeling can be used for the development of an effective time-temperature poling protocol. It is shown that for a high chromophores orientation the poling temperature should be some 20-30 K higher than the glass transition T-g.