THERMOTROPIC HYDROCARBON SIDE-CHAIN LIQUID-CRYSTALLINE POLYMERS .1. SYNTHESIS AND CHARACTERIZATION OF MONOMERS AND MODEL COMPOUNDS

A series of six new hydrocarbon monomers has been prepared by a versatile synthetic procedure. The new monomers are 1-alkene derivatives containing a biphenyl mesogen. Six new hydrocarbon twinlike model compounds have also been prepared. The synthesis permits facile variation of the length of flexible spacers as well as the alkyl substituents on the biphenyl mesogens. The liquid crystaline properties of the monomers and model compounds have been studied with differential scanning calorimetry, polarized light optical microscopy, and X-ray diffraction. Four of the six monomers and three of the six model compounds were found to exhibit smectic B liquid crystalline phases. The effect of the variation of the alkyl substituent on liquid crystalline properties is discussed. Substitution of the biphenyl mesogen by alkyl groups in the para positions appears necessary for the development of liquid crystallinity.