Synthesis and Nonlinear Optical Properties of Novel Y-Type Polyesters with Enhanced Thermal Stability of Dipole Alignment

Abstract

2,3-Di-(2′-hydroxyethoxy)-4′-nitrostilbene (3) was prepared and condensed with terephthaloyl chloride and adipoyl chloride to yield novel Y-type polyesters (4–5) containing the NLO-chromophores dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4–5 were soluble in common organic solvents such as acetone and dimethylsulfoxide. They showed thermal stability up to 300°C in thermogravimetric analysis with glass-transition temperatures obtained from differential scanning calorimetry in the range of 83–95°C. The second harmonic generation (SHG) coefficients (d 33 ) of poled polymer films at the 1064 cm−1 fundamental wavelength were around 3.68 × 10−9 esu. The dipole alignment exhibited high thermal stability up to the glass-transition temperature due to the partial main-chain character of polymer structure, which was acceptable for NLO device applications.