Improvement of oxygen permselectivity of a rigid helical polyphenylacetylene: Effect of flexible groups, degree of polymerization, composites, thickness, orientation, and network formation

Abstract In order to improve oxygen permselectivity of a rigid helical poly(alkenylphenylacetylene) membrane having a columnar liquid crystalline structure, several chemical and membrane structures including the degree of polymerization and the orientation of the macromolecules were modified and controlled. Introduction of longer alkenyl or flexible siloxane groups significantly enhanced oxygen permeability (PO2) and by reducing the degree of polymerization and the thickness of the membranes, or by the formation of network structures oxygen permselectivity (α = PO2/PN2) was effectively enhanced. The membranes from polymers with very small degree of polymerization and perpendicular orientation had extremely high α. In spite of the membranes from the polymers having the identical chemical structure, their performances could be optimized by controlling several membrane structures.