Side-chain liquid-crystalline polymers from the alternating copolymerization of maleic anhydride and l-olefins carrying biphenyl mesogens

Side-chain liquid-crystalline copolymers (SCLCPs) were synthesized from the alternating copolymerization of maleic anhydride with mesogenic 1-olefins. These SCLCPs showed high glass transition temperatures and highly ordered smectic mesophases. The mesophase width increased with spacer length. The t erminal alkyl group length determined the degree of order in the heretic me sophase that was present just above the glass transition temperature. A ter minal methoxy group induced a hexatic smectic B mesophase, intermediate ter minal alkyl groups induced a smectic E mesophase, and long terminal alkyl g roups induced a crystal smectic B mesophase. If the spacer was shorter than the terminal alkyl group, an interdigitated smectic A mesophase was found in which the terminal alkyl groups overlap. A strong correlation was found between the glass transition temperature and the temperature at which the h exagonal or orthorhombic ordered mesophase disappears. Introduction of an e ater linkage between the spacer and biphenyl mesogen or replacing the termi nal alkoxy group by a cyano terminal group induced a lowering of transition temperatures and a lower degree of order in the mesophase.