Liquid crystalline polymers I. Main chain thermotropic poly(arylidene-ether)s containing cyclopentanone moiety linked with polymethylene spacers

A new series of poly(arylidene-ether)s containing cyclopentanone was synthesized by polycondensation of 4,4'-diformyl-alpha,omega-diphenoxyalkane 1-4 and 4,4'-diformyl-2,2'-dimethoxy-alpha,omega-diphenoxyalkane 5-8 with cyclopentanone. The inherent viscosity of the polymers were in the range of 0.35-1.23 dl/g. Their thermotropic liquid crystalline properties were examined by DSC, optical polarizing microscopy using a heated stage, and thermogravimetric analyses. Almost all the polymers exhibited thermotropic liquid crystalline properties. In most cases the mesophase extends up to 358 degrees C, where the thermal decomposition prevents further observations. The polymer 14 with (n = 4), having high molecular weight, was synthesized in high yields and showed better solubility in organic solvents, such as halogenated hydrocarbons. In addition, the crystallinity of some polymers was examined by X-ray analysis, and they showed some degree of crystallinity. (C) 2000 Elsevier Science Ltd. All rights reserved.