Liquid-crystalline rod–coil polymers based on poly(ethylene oxide)s and the influence of the complexation of LiCF3SO3 on the liquid-crystalline assembly

Abstract

The synthesis and characterization of rod–coil polymers of ethyl 4′-(4′-oxy-4-biphenylcarbonyloxy)-4-biphenylcarboxylate with polyethylene oxide of three (3–4), seven (7–4), twelve (12–4) and sixteen (16–4) ethylene oxide units, of 4′-(4′-oxy-4-phenylcarbonyloxy)-4-biphenylcarboxylate with poly(ethylene oxide) of sixteen ethylene oxide units (16–3), and of ethyl 4′-oxy-4-biphenylcarboxylate with poly (ethylene oxide) of sixteen ethylene oxide units (16–2) are described. All the rod-coil polymers except 16–2 display a layered smectic mesophase and, in particular, 16–4 shows a microphase-separated morphology. The complexes of 16–4 with up to 0.3 mol of LiCF₃SO₃ per mol of ethylene oxide units are also prepared. The rod-coil polymer 16–4 exhibits an enantiotropic smectic B (S_B) mesophase. The complexes with 0.05 and 0.1 mol of LiCF₃SO₃, however, exhibit an enantiotropic smectic A (S_A) mesophase in addition to an S_B phase. In contrast with the complexes with 0.0–0.1 mol of LiCF₃SO₃, the complexes with 0.2 and 0.3 mol do not exhibit any smectic mesophases; however, they display a cylindrical micellar mesophase.