Preparation of a novel Y-type nonlinear optical polyester with high, second harmonic generation thermal stability

2,4-Di-(2′-hydroxyethoxy)benzylidenemalononitrile was prepared and condensed with terephthaloyl chloride to yield a novel Y-type polyester containing dioxybenzylidenemalononitrile, nonlinear optical chromophores as part of the polymer backbone. The resulting polymer was soluble in common organic solvents such as acetone and N,N-dimethylformamide and displayed thermal stability up to 300 °C with a glass-transition temperature of ∼94 °C. The second harmonic generation coefficient (d33) of poled polymer film at the 1064 nm fundamental wavelength was 6.48 × 10−9 esu. The dipole alignment exhibited high thermal stability even at 10 °C higher than Tg and there was no second harmonic generation decay <105 °C due to the partial main-chain character of the polymer structure.