Polymer conformation in supramolecular complexes with wedge-shaped ligands: Exploring the impact of the liquid-crystalline organization

Abstract

The chain conformation of poly(2-vinylpyridine) (P2VP) complexed by 4-((4-((3,4,5-tris(dodecyloxy)benzoyl)oxy)phenyl)diazenyl)benzenesulfonic acid at different degrees of neutralization (DN) was addressed by small- and wide-angle neutron scattering technique. To get information on the conformation of P2VP chains spatially confined within lamellar and columnar mesophases at different DNs, the complexes were prepared from a blend of protonated and deuterated P2VP. The 2D scattering patterns of extruded fibers show that at low DN the complex self-organizes in a lamellar phase. The inertial mean distances in the direction parallel and perpendicular to the fiber axis reveal the formation of compact disc-like globules of individual P2VP chains at DN = 25 and 33%. With the increase of DN the interaction between the neighboring side groups along the backbone increases. This results in formation of hexagonal columnar phase at DN = 50%, in which the P2VP macromolecules are confined within cylindrical channels forming most probably a disordered helical conformation. At DN = 1.0, the enhanced rigidity of the complex hinders the accommodation of the ligands at the interface with polymer chain. This results in appearance of non-bonded side groups in the columns giving rise to a poorly-ordered structure. In contrast to more rigid chains of poly(4-vinylpyridine), the transition from lamellar to columnar mesophase in P2VP occurs at lower DNs, indicating a significant role of the chain flexibility in the formation of ordered structures.