ALTERNATIVE SYNTHETIC STRATEGIES FOR SCHIFF-BASE DERIVED LIQUID-CRYSTAL POLYMERS - A COMPARATIVE-STUDY

Semiflexible liquid crystalline polymers based on Schiff bases as meso genic cores have been synthesized through different synthetic strategi es. The mesogenic cores are derived from 1,5-naphthalenediamine linked to a polymethylenic spacer by means of ether or ester groups. The syn thetic strategies differ in the disconnection of the molecules to desi gn the synthesis of the repeating units. Polymers were synthesized eit her as polyazomethines, where imine bonds are formed in the polymer sy nthesis, or as polyethers or polyesters, where the ether or ester grou ps are formed at the polymer-forming stage. The influence of the synth etic method and the linking groups between mesogenic core and flexible spacer on the thermal and mesogenic properties has been analyzed by D SC, thermogravimetry, and optical microscopy. The possibility of obtai ning hydroxy-functionalized polymers by different synthetic strategies has been studied as well as the influence of these groups on the ther mal and mesogenic properties. (C) 1996 John Wiley & Sons, Inc.