Preparation and Properties of A Novel Y-type Nonlinear Optical Polyester with Dioxybenzylidenecyanoacetate Groups

摘要

Methyl 2,4-di-(2'-hydroxyethoxy)benzylidenecyanoacetate (3) was prepared and polymerized with terephthaloyl chloride to yield a novel Y-type polyester 4 containing 2,4-dioxybenzylidenecyanoacetate groups as NLO-chromophores, which constituted parts of the polymer backbone. The resulting polymer 4 is soluble in common organic solvents such as acetone and N, N-dimethylformamide. Polymer 4 showed thermal stability up to 280 °C in thermogravimetric analysis with glass-transition temperature obtained from differential scanning calorimetry near 108 °C. The second harmonic generation (SHG) coefficient (d_(33)) of poled polymer films at the 1064 nm fundamental wavelength was around 3.54 x 10~(-9) esu. The dipole alignment exhibited a thermal stability up to near T_g and no significant SHG decay was observed below 100 °C due to the partial main-chain character of polymer structure, which is acceptable for NLO device applications.