SYNTHESIS AND CHARACTERIZATION OF POLYURETHANES WITH NONLINEAR-OPTICAL ACTIVE GROUPS

Polyurethane-based polymers for second-order nonlinear optical effect were synthesized by the polycondensation of diols containing nonlinear active dyes, such as N,N-di(2-hydroxyethyl)-4-nitroaniline and 4'-nitrobenzylidene-4-[N,N-di(hydroxyethylamino) aniline)] with tolylene-2,4-diisocyanate or hexamethylene diisocyanate. The synthesized polymers were characterized by IR, H-1-NMR and element analysis. The inherent viscosity measured in dimethylformamide was 0.15-0.25dl/g. The initial decomposition obtained from TGA appeared at 220-270-degrees-C in N2-atmosphere. The glass transition temperatures were detectable at 68-138-degrees-C whose values strongly depend on the rigidity of polyurethane backbone. X-ray diffractograms showed that all of the polymers are amorphous. The UV-visible absorption spectra displayed main absorption bands at lambda(max) 400nm for pi-pi* electronic transition of nitrophenyl derivatives and at lambda(max) 460nm for the dyes containing azomethine linkage.