MONOTROPIC LIQUID-CRYSTAL BEHAVIOR IN 2 POLY(ESTER IMIDES) WITH EVEN AND ODD FLEXIBLE SPACERS

Mesophase behavior of two poly(ester imides) synthesized from N-[4-(chloroformyl)phenyl]-4-(chloroformyl)phthalimide and 1,4-butanediol or 1,9-nonanediol has been extensively studied. One of the polymers has four methylene units (even) and the other nine methylene units (odd) in its respective flexible spacers. Both polymers show monotropic liquid crystal behavior which has been identified by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and polarized light microscopy (PLM) experiments. The liquid crystal phase seems to be more ordered than the nematic phase. Further crystallization from this liquid crystal phase can be achieved during cooling and/or isothermal experiments below the isotropic melt to liquid crystal transition temperature. This indicates that the molecules in the liquid crystal phase possess high mobility. Isothermal experiments on these polymers at temperatures above the monotropic liquid crystal transition lead to direct crystallization from the isotropic melt with large axilitic or spherulitic texture.