Synthesis and Nonlinear Optical Properties of Novel T-type Polyester Containing Thiophene with Enhanced Thermal Stability

Abstract

A novel T-type polyester 7 containing 1-(2,5-dioxyphenyl)-2-{5-(1,2,2-tricyanovinyl)-2-thienyl}ethenes as nonlinear optical (NLO) chromophores, which are part of the polymer backbone, was prepared and characterized. Polyester 7 is soluble in common organic solvents such as dimethylsulfoxide and N,N-dimethylformamide. It showed a thermal stability up to 300 o C in thermogravimetric analysis thermogram and the glass-transition temperature (Tg) obtained from differential scanning calorimetry thermogram was around 113 o C. The second harmonic generation (SHG) coefficient (d33) of poled polymer films at 1,560 nm fundamental wavelength was around 1.85 pm/V. The dipole alignment exhibits a greater thermal stability even at 10 o C higher than Tg, and there is no SHG decay below 125 o C due to the partial mainchain character of the polymer structure, which is acceptable for nonlinear optical device applications.