Synthesis of liquid crystalline polyesterimides by melt polymerization and its application to polymer-dispersed liquid crystal

Abstract

N-(4-Carboxyphenyl)trimellitimide( DAI)was synthesized from trimellitic anhydride and p-aminobenzoic acid by a one-step reaction utilizing m-cresol as a solvent. DAI was reacted with hexanediol and nonanediol to give bishydroxyhexyltrimellitimide (BHHI) and bishydroxynonyltrimellitimide (BHNI), respectively. Thermotropic liquid crystalline polyesterimides with BHHI and BHNI as a mesogenic group and 6 and 9 methylene units as a spacer were synthesized by a direct melt-polymerization method similar to the one used in the preparation of commercial polyester. Polyesterimides were characterized by IR, H-1-NMR, DSC, and a polarized optical microscope. Their application as a matrix (binder) of polymer-dispersed liquid crystal (PDLC) was investigated with 4-heptyloxybenzoic acid as a low molecular weight liquid crystal (LMWLC). From the PDLC experiment, polyesterimides were found to be useful as a matrix for the high-temperature PDLC above 100 degrees C. (C) 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1517-1522, 1998