Gas Transport Properties of n-Alkylated Liquid Crystalline Aromatic Polyester Oriented by Magnetic Field

Liquid crystalline aromatic polyester with n-tetradecyl side chains, B-C14 was synthesized from the 1,4-di-(n-tetradecyl ester) of 1,2,4,5-benzenetetracarboxylic acid and 4,4′-biphenol, to clarify the ability of magnetic orientation and gas transport properties of this polyester. B-C14 behaved as a thermotropic liquid crystal and formed a layered structure composed of alternating rigid aromatic main chain layers and flexible n-alkyl side chain layers. In this study, B-C14 membrane was prepared by annealing at 125°C for 12 h under a magnetic field (9.4 T), whose direction was perpendicular to the membrane surface. From WAXD studies, and solid-state 13C NMR CP/static measurements, we concluded that the layered structure of B-C14 aligned with the c-axis being perpendicular to membrane surface. From gas permeation measurements, we concluded that this successfully magnetic-oriented B-C14 membrane leads to a higher gas diffusion coefficient.