Effect of an applied electric field on liquid crystalline membranes: control of permeability

This paper considers the development of liquid crystalline variable permeability membranes. The electrically induced changes in permeability of a liquid crystalline membrane composed of a 23% w/v solution of poly(γ-benzyl-l-glutamate) (PBLG) in dichloromethane are described. PBLG exists in the cholesteric mesophase in solution in a suitable α-helicogenic solvent. When an electric field is applied to a thin membrane comprised of this material, a transition to the nematic mesophase is triggered, and the permeability of the membrane for small organic permeants increases. This increase takes the form of a 50-60% increase in the steady state flux through the membrane.