HIGHLY SELECTIVE MEMBRANES FOR THE SEPARATION OF ORGANIC VAPORS USING SUPER-GLASSY POLYMERS

THE RECOVERY OF ORGANIC COMPOUNDS FROM AIR AND OF HIGHER HYDROCARBON VAPORS FROM METHANE ARE RELATED SEPARATIONS OF CONSIDERABLE INDUSTRIAL IMPORTANCE. MEMBRANES ABLE TO PREFERENTIALLY PERMEATE THE MINOR ORGANIC COMPONENT ARE BEING DEVELOPED FOR BOTH OF THESE APPLICATIONS. FOR AN EFFICIENT PROCESS, A HIGH ORGANIC VAPOR/PERMANENT GAS SELECTIVITY IS REQUIRED. CONVENTIONAL GLASSY POLYMERS, WHICH ARE SELECTIVE FOR THE PERMANENT GAS OVER THE ORGANIC VAPOR, ARE SUITABLE FOR THIS APPLICATION. RUBBERY POLYMERS, WHICH ARE ORGANIC VAPOR SELECTIVE, ARE IN COMMERCIAL USE, BUT HAVE INADEQUATE SELECTIVITY FOR MANY APPLICATIONS. RECENT WORK SHOWED THAT MULTI-FREE-VOLUME, SUPER-GLASSY POLYMERS SUCH AS POLY(1-TRIMETHYLSILYL-1-PROPYNE) [PTMSP] CAN EXHIBIT A BUTANE/METHANE SELECTIVITY OF 30 WITH THE MIXED GASES. THIS SELECTIVITY IS THE HIGHEST EVER OBSERVED FOR THIS IMPORTANT MIXTURE AND IS COMPLETELY UNEXPECTED FOR A GLASSY POLYMER. THE REASON FOR THIS EXTRAORDINARY RESULT IS RELATED TO THE HIGH FREE VOLUME AND THE LARGE INTERMOLECULAR CHAIN SPACING OF THE SUPER-GLASSY POLYMER. IN THIS PHASE I PROJECT, A DETAILED STUDY WILL BE CONDUCTED OF THE VAPOR SEPARATION PROPERTIES OF PTMSP, RELATED POLYACETYLENES, AND BLENDS THEREOF WITH A NUMBER OF IMPORTANT ORGANIC VAPOR/GAS MIXTURES. IN CONTRAST TO RESULTS OF PREVIOUS STUDIES OF HIGH FREE VOLUME GLASSY POLYMERS WITH PERMANENT GASES, THESE POLYMERS ARE EXPECTED TO SHOW STABLE PERMEATION PROPERTIES IN THE PRESENCE OF ORGANIC VAPORS.