Preparation and characterisation of composite membranes made with UV curable perfluoropolyethers

The aim of this work was the functionalization of different microfiltration membranes with the use of UV-curable perfluoropolyethers (PFPE) in order to make them hydrophobic. PFPEs are a well known class of partially fluorinated oligomers which possess several advantages typical of fluorinated polymers like chemical and thermal stability in addition to high hydrophobicity. The ones used here, produced by Solvay Specialty Polymers, have special (meth)acrylic functionalities which make them UV or thermal cross-linkable [1]. In this work several different substrates were immersed in PFPE solutions dried and exposed to UV radiation. The resulting composite membranes can be advantageously used as membranes for Membrane Distillation applications. The feasibility of this innovative approach allows to explore the use of different polymeric substrates with different physical, chemical and morphological properties. The coating can be applied on just one side on an hydrophilic membrane (realizing an hydrophilic/hydrophobic membrane [2]) or on both sides of whatever substrate just obtaining a fully hydrophobic membrane. Characterization results mainly evidenced as the presence of PFPE can tune the properties of many different polymeric substrates (Polyethersulfone, Cellulose, Polyammide etc) significantly enhancing their hydrophobicity but preserving their initial morphology. Preliminary experimental results on performances of such membranes with Direct contact membrane distillation will be presented. [1].W.O. 2013/164287 A1 Composite membrane comprising layer of perfluoropolyether on hydrophilic substrate [2] M.Qtaishat, M. Khayet, T. Matsuura. J. of Membrane Science, 329 (2009) 193-200