THIN-FILMS OF ACETALIZED POLY(VINYL ALCOHOL) AS NONLINEAR OPTICAL-MATERIALS

Acetalized poly(vinyl alcohol)s (PVA) having pendant nonlinear optically (NLO) active groups were synthesized in order to investigate second harmonic generation (SHG) by using two types of poling methods of NLO active moieties; namely, one was Langmuir-Blodgett (LB) orientation and the other was electric field (EF) poling. It was found that the new polymers having pendant NLO active groups showed sharp surface pressure-area (pi-A) curves to form thin films on the surface of water but no active SHG was observed. On the other hand, the polymer films with a support of stearamide showed a SHG activity. When the new polymers were EF poled using colona poling method, SHG was also observed and the SHG activity was estimated as 40.8 pm V-1. The new NLO polymers poled by the EF method showed small SHG relaxation and were useful as a new type SHG material.