Congratulations to Matthew Vasuta in the Jennings lab! Matthew鈥檚 paper 鈥淔luorocarbon Minimization Via Semifluorinated Copolymer Films by Combining Spin Coating and Ring-Opening Metathesis Polymerization鈥� has been selected as a VINSE Spotlight Publication.
Matthew and his collaborators addressed three challenges associated with the synthesis of fluorocarbon thin films: long synthesis times, bulk amounts of solvent, and excess use of per- and polyfluoroalkyl substances (PFAS). By combining spin coating and ring-opening metathesis polymerization together in one synthetic step, film synthesis can be confined to < 2 min with < 1 mL of solvent. Additionally, from the migration of fluorocarbon moieties to the interface of the film when spin coating, a fluorocarbon surface can be maintained with only 7 % of the fluorocarbon repeat unit in the bulk of the film. This work demonstrates an overall more sustainable synthesis route to thin films and coatings that need fluorinated surfaces but do not require large amounts of bulk PFAS over the entirety of the film.
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Authors: Matthew P. Vasuta, Zane J. Parkerson, Tyler D. Oddo, Bridget R. Rogers, and G. Kane Jennings
Abstract: Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in society largely due to their unique surface properties,
but significant health concerns associated with these substances underscore the need for PFAS reduction strategies. We report a
method to substantially reduce the amount of PFAS, solvent, and time needed to synthesize a low surface energy polymer film
through the copolymerization of norbornene (NB) with 5- (perfluoro-n-alkyl)norbornenes (NBFn) in a single process that combines spin coating with ring-opening metathesis polymerization (scROMP). The unique scROMP approach efficiently integrates polymer film synthesis and deposition into one rapid process, converting monomer into polymer films in <2 min with <1 mL of solvent for a 36 cm2 film. Perfluoroalkyl chain lengths, n, of 4, 6, and 8 were examined, with the fluorocarbon component tending to dominate the surface for all n, exhibiting water contact angles comparable to those of the fluorocarbon homopolymer even with as little as 2% NBFn in the contacting monomer. As a potential application, these semifluorinated copolymer films were used in ethanol dehydration as low PFAS substitutes for amorphous fluoropolymer membranes. Even 7% fluorocarbon in the polymer (or 2% in the monomer) caused an order-of-magnitude increase in selectivity over a fully hydrocarbon membrane, with additional fluorination up to 63% (50% in monomer), leading to another order-of-magnitude enhancement and properties similar to the pNBFn homopolymer. Additionally, the dense outer fluorocarbon layer provided an ideal setup to estimate the sorption and diffusion components of selectivity for fluorocarbon and hydrocarbon groups within a membrane.