| dc.description.abstract | Membrane technologies can offer an order of magnitude greater energy efficiency than thermally driven separations such as distillation. The fabrication of robust, solvent-stable active layers on inexpensive supports is essential for the widespread utilization of this technology by industry. To generate robust films, we introduce a method named spin coating ring opening metathesis polymerization (scROMP) of 5-(perfluoro-n-alkyl)norbornenes (NBFn) with perfluoroalkyl side chain lengths (n) of 4, 6, 8, and 10 to generate semi-fluorinated films on polyacrylonitrile (PAN) supports. The scROMP method combines the polymerization and deposition of the membrane selective layer into a rapid and sustainable 2 min process with well under 1 mL of solvent. The polymer films grown by this innovative method were then characterized and their effectiveness as pervaporation membranes for the dehydration of a 90 wt% aqueous ethanol solution was analyzed. pNBFn membranes exhibited greater solvent stability than their nonfluorinated polynorbornene (pNB; n = 0) counterpart while retaining excellent thermal stability, evidenced by reduced swelling in polar and nonpolar solvents, inhibition of oxidation reactions at the polymer backbone, and <1% mass loss in TGA up to 130°C. Furthermore, pNBF8 has shown the greatest promise for ethanol dehydration, obtaining a selectivity of 177 and a flux of 180 g/m2h while sustaining this high level of performance for >40 h of continuous operation for ethanol/water separations. This performance surpasses that of commercial amorphous perfluoropolymers (APFP) studied in literature while matching their favorable stability and reducing the risk of perfluoro alkyl substance (PFAS). This study successfully demonstrates the ability of the scROMP technique to efficiently fabricate and screen specialty polymers for membrane applications and sets the stage for additional research into the use of pNBFn in polymer blends, co-polymers, or as a homopolymer for ethanol dehydration and other chemical separations including organic solvent nanofiltration. | |
