Thermotropic Liquid Crystalline Complexes of Hydrogen-Bonded Poly(pyridylpyridinium dodecyl methacrylate) Bromide and Octylphenol

An ion-containing polyamphiphile, poly(ω-pyridylpyridinium dodecyl methacrylate) bromide, was successfully complexed with 4-octylphenol by hydrogen bonding, with no interference from the ionic moieties. Hydrogen bonding of the surfactant to the polymer is virtually complete up to near-equimolar phenol/pyridyl ratios. The complexation generates a well-behaved thermotropic liquid crystalline system from a low-melting surfactant and a polymer with ill-defined mesomorphism. The complex melts at relatively high temperatures into a liquid crystalline (smectic A) phase before becoming isotropic. The long period of the mesophase is almost identical to that of the polyamphiphile alone, is between the calculated lengths of the uncomplexed and complexed polymer repeat units, and is essentially independent of the complex stoichiometry. This can be rationalized by the same model presented in a previous publication for an ionically complexed polyamphiphile−surfactant system.