Activation of PVDF membranes through facile hydroxylation of the polymeric dope
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Musthafa O. Mavukkandyb) Department of Chemical Engineering, Masdar Institute, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates
Joanna Kujawa Department of Chemical Engineering, Masdar Institute, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates; and Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Toruń 87-100, Poland
Suzana P. Nunes Biological and Environmental Science and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900, Saudi Arabia
Hassan A. Arafata) Department of Chemical Engineering, Masdar Institute, Khalifa University of Science and Technology, Abu Dhabi, United Arab Emirates (Received 28 July 2017; accepted 25 September 2017)
A method comprising a two-step alkali/acid treatment of poly (vinylidene fluoride) (PVDF) polymer is developed for the fabrication of flat-sheet PVDF membranes functionalized with labile hydroxyl groups. This method involves the application of a short-duration modification in alkali medium (5% KOH). Extensive characterizations were performed on the prepared membranes. Modification of the polymer altered the crystallinity of the PVDF from a mixture of both a and b phases to a predominant b phase. Lower work of adhesion of the modified membrane indicated the formation of a more hydrophobic and wetting-resistant membrane surface. Centrifugation of the polymer dope after the modification had a pronounced impact on the properties of the resultant membranes. This protocol could be utilized in fine-tuning the properties of PVDF membranes for various target-specific applications such as membrane distillation. This method can also be used in functionalizing PVDF membranes further by exploiting the labile –OH group present on the membrane surface.
I. INTRODUCTION
Membrane technology has a huge potential in different applications, including petrochemicals, pharmaceutical and food and beverages industries, and water and wastewater treatment. Membrane-based processes such as microfiltration (MF), ultrafiltration (UF), nanofiltration, membrane distillation, and reverse osmosis are extensively used for desalination, and water and wastewater treatment. One of the widely used membrane materials is poly (vinylidene fluoride) (PVDF). PVDF is a highly inert and pure thermoplastic fluoropolymer made by the polymerization of vinylidene difluoride. Contributing Editor: Erik G. Herbert a) Address all correspondence to this author. e-mail: [email protected] b) These authors contributed equally to this work. This paper has been selected as an Invited Feature Paper. DOI: 10.1557/jmr.2017.403
It possesses high thermal and mechanical stability and excellent chemical and ultraviolet resistance.1,2 Furthermore, PVDF has good thermodynamic affinity with various polymers such as hexafluoropropylene,3 chlorotrifluoroethylene,4 and methyl methacrylate.1 Therefore, it is commonly utilized in various membrane applications such as MF, UF, membrane distillation (MD), and membrane contactors.5–7 It is also an approp
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