Nonlinear optical polyimides with various substituents on chromophores: synthesis and glass transition temperature

Glass transition temperature (T-g) of nonlinear optical polyimide was observed with a variation of substituents on chromophore side chain. Several alkyls and functional groups were synthetically introduced on both electron accepting and donating groups of the chromophores. The polymers were thermally characterized with a differential scanning calorimetric analysis (DSC). The glass transition occurred at a range of 160-230 degreesC according to introducing substituents. An ester group in the chromophore tends to lower T-g in the corresponding polyimide compared to a nitrile or a sulfone. Flexible and bulky substituents led to decrease T-g of the polymer. Electro-optic coefficients were measured to compare nonlinear optical performance of similar polymers with different Tg. (C) 2004 Elsevier B.V. All rights reserved.