Preparation and properties of high-pretilt-angle polyimides based on an alicyclic dianhydride and long alkyloxy side-group-containing diamines

A series of polyimides were prepared by a solution polycondensation reactio n between 3-carboxylmethylcyclopentane-1,2,4-tricarboxylic dianhydride and 4-alkyloxybenzene-1,3-diamines in N-methyl-2-pyrrolidone and chemical imidi zation with triethylamine and acetic anhydride. These polyimides possess gr eat organo-solubility, high optical transparency, and high pretilt angles. They are soluble not only in strong polar aprotic organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, m-cre sol, and 1,4-butyrolactone but also in common low-boiling-point solvents su ch as chloroform and tetrahydrofuran, and some are even soluble in acetone. They exhibit high transparency at wavelengths greater than 320 nm. They ca n generate pretilt angles greater than 5 degrees, and some can even achieve pretilt angles greater than 10 degrees. The pretilt angle of a polyimide i ncreases with the increasing length of the alkyloxy side group. The polyimi des possess glass-transition temperatures between 180 and 230 degrees C and thermal decomposition temperatures (onset temperatures) of about 435 degre es C. (C) 2000 John Wiley & Sons, Inc.