Abstract
Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) porous membranes are fabricated via thermally induced phase separation (TIPS) with mixed diluent (dibutyl phthalate (DBP)/dioctyl phthalate (DOP)). The effects of mixed diluent are discussed in detail in term of morphology, mean pore size, selective wettability, etc. The results show that the membrane structure changes from spherulitic to bicontinuous with the change of DBP/DOP ratio. It is also found that the degree of crystallization decreases with the decrease of DBP/DOP ratio in mixed diluent. When liquid–liquid (L-L) phase separation precedes solid–liquid (S-L) phase separation, the obtained membranes have outstanding hydrophobicity and lipophilicity, excellent mechanical property. Additionally, the PVDF-HFP hybrid membranes are prepared with silica (SiO2) particles and the effect of SiO2 content on structure and properties is discussed. It is found that the PVDF-HFP hybrid membrane with 2 wt % SiO2 (M3-S2) has better properties and higher filtration rate and separation efficiency for surfactant-stabilized water-in-oil emulsion separation. Moreover, the membrane M3-S2 also exhibits excellent antifouling performance for long-running.
Highlights
An emerging fluoro-copolymer, polyvinylidene fluoride (PVDF)-HFP, is attracting more and more attention.PVDF-HFP can be obtained via emulsion polymerization of vinylidene fluoride (VDF) and hexafluoropropylene (HFP) [1]
Most studies focused on the fabrication of PVDF-HFP membranes via non-solvent induced phase separation (NIPS) method and the obtained membranes were applied in processes of membrane distillation (MD), polymer battery and gas absorption, etc
The mean pore size of PVDF-HFP porous membranes was investigated using automatic mercury porosimeter (AutoPore IV-9500, Tektronix, Beaverton, OR, USA) and the porosity of membrane was measured by a gravimetric method and calculated as follows: ε(%) =
Summary
An emerging fluoro-copolymer, PVDF-HFP, is attracting more and more attention. Khayet et al [5] prepared PVDF-HFP hollow fiber membranes via NIPS method and studied the effects of polymer concentrations on MD process. Wang et al [7] prepared PVDF-HFP flat-sheet asymmetric membranes and investigated the effects of molecular weight of PEG on performance for MD process. It was found that desirable the effects of diluent compositions on membrane structure and performance. Zhang et al [20] modified PVDF membrane surface by doping ammonia water into polymer solution formed micro/nanostructure via the modified phase-inversion process. PVDF-HFP and mixed diluent (DBP)/(DOP) are used for fabricating porous membranes via TIPS method. The effect of the interaction between mixed diluent and PVDF-HFP on membranes via TIPS method.
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