Supercritical fluid decontamination (SCFD) of poly(vinylidene fluoride) (PVDF) and further upcycling into highly porous aerogels with a well defined microstructure

Abstract

Per- and polyfluoroalkyl substances (PFAS) like polyvinylidene fluoride (PVDF) have a wide range of applications due to their high stability and persistency, but their production is increasingly being restricted because the mentioned outstanding properties simultaneously impose drawbacks in terms of poor (bio)degradability. The lack of appropriate and industrially established solutions for handling and reuse of PVDF after fulfilling its first purpose aggravates this environmental issue. The presented work outlines a novel approach for the upcycling of PVDF waste material by supercritical fluid decontamination of used PVDF and subsequent conversion into a value-added, highly porous PVDF-based material with an open-cell structure, a so-called aerogel, containing a well-defined pore morphology on the microscale. The work further shows that the synthesis of an aerogel from used PVDF tolerates impurities to a certain extent, for which the previous treatment does not necessarily have to render a material 100 % free of contaminations. As a result, a proof-of-concept is given for an industrially feasible process that is capable of upcycling a valuable high-performance polymer into a sophisticated porous material, thereby avoiding the release of potentially toxic fluorine compounds and opening a path towards a circular economy for contaminated PVDF.