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1 Polish Journal of Chemistry

1 2007

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Physico-Chemical Studies of Polyurethanes with Dipolar Chromophore

Arora S., Kumar S.

Polish Journal of Chemistry

2007

Vol. 81, nr 2

225-235

Polyurethanes with varying concentrations of dipolar chromophore, namely 4-{4-[bis(2- hydroxyethyl) amino] phenylazo} benzonitrile were synthesized and characterized by thermal and spectral techniques. The effect of varying concentrations of dipolar chromophore on physicochemical properties of the polymers was studied. The polymers were obtained with very high yield possessing solubility in polar aprotic solvents like N,N-dimethylformamide, tetrahydrofuran, etc. Molecular weights of the resulting polymers determined by GPC were found to be in the range Mw = 5050–5730 (Mw/Mn =1.89–1.98). DSC curves of the polymers showed absence of melting process, indicating the polyurethanes to be noncrystalline. The synthesized polymers were found to possess high glass transition temperatures (Tg) and high thermal stabilities. Optical band gaps of these polyurethanes were in the range 2.30–2.51 eV. Vacuum-deposited thin films of these polyurethanes were corona-poled to study relaxation behaviour of aligned dipoles. The results indicate that polymeric films possess good temporal stability of aligned dipoles.