New polymers of carbonic acid.: XXV.: Photoreactive cholesteric polycarbonates derived from 2,5-bis(4′-hydroxybenzylidene)cyclopentanone and isosorbide

Several binary copolycarbonates were prepared by polycondensation of 2,5-bis(4-hydroxybenzylidene)cyclopentan BHBC, with methylhydroquinone, MHQ, hydroquinone 4-hydroxybenzoate, HQHR, or isosorbide. Furthermore, five ternary copolycarbonates were prepared based on the aforementioned monomers. All polycondensations were conducted in pyridine with trichloromethyl chloroformate as condensing agent. All polycarbonates were characterized by elemental analyses, viscosity and DSC measurements, IR and H-1- and C-13-NMR spectroscopy, optical microscopy, and the WAXS powder pattern. All isosorbides containing binary and ternary copolycarbonates were found to form a cholesteric melt, but only three of them were capable to form a stable Grandjean texture upon shearing. (C) 1999 John Wiley & Sons, Inc.