Ordering of Poly(<i>p</i>-phenylene ethynylene)s in Liquid Crystals

Abstract

Poly(phenylene ethynylene)s were designed and synthesized that are completely soluble in nematic\nliquid crystalline solvents at molecular weights (GPC, relative to PS) of more than 100 000. These materials\nexperience a chain extended rod conformation under these conditions with the polymer chains highly aligned\nwith the liquid crystal director and an enhanced conjugation length determined by optical spectroscopy. Structure−property relationships are investigated that reveal the role of steric congestion about the polymer mainchain in\ndetermining the order parameter of the polymers. It was also found that the order polymer parameters increased\nwith increasing molecular weights.