Development of Pervaporation Membrane for Ethanol Separation by Plasma Polymenzatlon of Fluorocarbons: A Model System of Separation by Hydrophobic Interaction and Future of Functional Membranes

Plasma polymerization has won its undisputed place in modern thin film technology. We revealed that the technique also allows to study separation mechanism of pervaporation (PV) membrane. The membrane prepared by various fluorocarbon plasmas combined with porous substrates was found to separate ethanol from dilute aqueous solution. In the PV process, the liquid mixture was supplied on the side of fluorocarbon film, and the other porous side was evacuated to remove permeated vapor. It was convinced that the mechanism might be preferential sorption of ethanol on plasma polymerized film by hydrophobic interaction. Particular emphasis is made on the method for seeking the optimum condition of membrane preparation, and also, the future scope of plasma polymerization as one of the powerful tools for developing more functionally sophisticated membranes in which molecular level of structures should be well organized at a characteristic scale for displaying a certain functionality.