3,4-Di-(2 -hydroxyethoxy)-4 -nitrostilbene (2) was prepared by the reaction of 2-iodoethanol with 3,4-dihydroxy-4 -nitrostilbene. Diol 2 was condensed with 2,4-toluenediisocyanate, 3,3 -dimethoxy-4,4 -biphenylenediisocyanate and 1,6-hexamethylenediisocyanate to yield novel Y-type polyurethanes 3-5 containing dioxynitrostilbene as a non-linear optical (NLO)-chromophore. Polymers 3-5 were soluble in common organic solvents, such as acetone and DMF. These polymers showed thermal stability up to 280 • C in TGA thermograms with T g values in the range of 100-143 • C in DSC thermograms. The approximate lengths of aligned NLO-chromophores of the polymers estimated from AFM images were around 2 nm. The SHG coefficients (d 33 ) of poled polymer films were around 4.5 × 10 −8 esu. Poled polymer films had improved temporal and long-term thermal stability owing to the hydrogen bonding of urethane linkage and the main-chain character of the polymer structure, which are acceptable for NLO device applications.

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Abstract2,5‐Bis‐(3,4‐dicarboxyphenylcarboxyethoxy)‐4′‐nitrostilbene dianhydride was prepared and reacted with 1,4‐phenylenediamine, 4,4′‐oxydianiline, 4,4′‐diaminobenzanilide, and 4,4′‐(hexafluoroisopropylidene)dianiline to yield unprecedented novel T‐type polyimides (4–7) containing 2,5‐dioxynitrostilbenyl groups as nonlinear optical chromophores, which constituted parts of the polymer backbones. 4–7 were soluble in polar solvents such as acetone and N,N‐dimethylformamide. They showed thermal stability up to 300 °C in thermogravimetric analysis thermograms; the glass‐transition temperatures obtained from differential scanning calorimetry thermograms were around 153 °C. The second harmonic generation (SHG) coefficients (d33) of poled polymer films at the 1064‐cm−1 fundamental wavelength were around 4.35 × 10−9 esu. The dipole alignment exhibited exceptionally high thermal stability even at 45 °C higher than the glass‐transition temperature, and there was no SHG decay below 200 °C because of the partial main‐chain character of the polymer structure, which was acceptable for nonlinear optical device applications. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3189–3199, 2004

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Summary: 1‐(2′,2′,3′,3′‐Tetracyanocyclopropyl)‐3,4‐di‐2′‐hydroxyethoxybenzene (4) was prepared by the reaction of bromomalononitrile with 3,4‐di‐(2′‐hydroxyethoxy)benzylidenemalononitrile (3). The dipole moment of diol 4, calculated by the ASED‐MO method, was 4.01 D. Diol 4 was condensed with 2,4‐toluenediisocyanate and 3,3′‐dimethoxy‐4,4′‐biphenylenediisocyanate to yield polyurethanes 5 and 6 containing tetracyanocyclopropane functionalities in the side‐group. The resulting polymers 5 and 6 were soluble in common organic solvents and the inherent viscosities were in the range of 0.25–0.30 dL · g−1. Solution‐cast films showed a thermal stability up to 280 °C with glass‐transition temperatures of 163–167 °C. The approximate lengths of aligned piezoelectric chromophores estimated from AFM images of poled polymer films were about 4 nm. Piezoelectric coefficients (d31) of the poled polymer films 5 and 6 were around 2.2–2.4 pC · N−1. These polymers showed good temporal and long‐term thermal stability due to the hydrogen bonding of the urethane linkage.