A nonlinear optical polyurethane functionalized with a heteroaromatic thiophene ring having a tricyanovinyl group

Abstract

A new functionalized polyurethane structure with a thiophene ring having a tricyanovinyl group in the polymer side chain was synthesized. The molecular weight of the final polymer was determined to be M-n = 1200 and M-w/M-n = 2.04. The resulting polymer was soluble in N-methylpyrrolidinone and could be processed into good optical quality films by spin casting at cs. 100 degrees C. it showed no weight loss up to 266 degrees C in the thermogravimetric analysis and a definite glass transition at 176 degrees C. The second-order nonlinear optical coefficient. d(33), was determined to be 51 pm V-1 from measuring the second harmonic generation (SHG) for a thin polymer film after poling treatment. The outstanding orientational stability of the aligned chromophores was observed up to about 150 degrees C, which originated from the rigid polymer backbone and the stabilizing function of the hydrogen bridges formed between the neighboring polyurethane chains.