Oxygen permselective characteristics of a poly(vinylchloride)/liquid crystal/fluorocarbon ternary composite membrane

Abstract

Poly(vinyl chloride) (PVC)/ N-(4-ethoxybenzylidene)-4'-butylaniline (EBBA)/perfluorotributylamine (PFTA) ternary composite membrane was prepared and its oxygen permselectivity was investigated. In this membrane system, PFTA was contained in micelles formed by a surfactant of an ABA-type block copolymer (L44). The oxygen permeability coefficient, P O 2 , for the PFTA-containing ternary composite membrane was greater than that for the PFTA-free binary one. The order of P O 2 for the ternary composite membrane was 10 −9 to 10 −8 cm 3 (STP)-cm −1-sec −1-cmHg −1, and the magnitude of the separation factor, P O 2 / P N 2 , about 3.5—4.0 in the temperature range of the nematic or isotropic state of EBBA. An increase in P O 2 caused by adding PFTA suggests that PFTA enhances the solubility of oxygen in the composite membrane surface. The ternary composite membrane showed a unique trend in its P O 2 / P N 2 — P O 2 relationship, that is, the magnitude of P O 2 / P N 2 increased simultaneously with that of P O 2 .