The preparation of microporous PVDF membranes with dithiphosphates and modification of surface properties by Helicon plasma

In recent years, Poly(vinylidene fluoride) (PVDF) has received great attention as polymer material for preparing microporous membranes due to its high mechanical strength, chemical resistance, thermal stability, well-controlled porosity and high hydrophobicity. PVDF microporous membranes have been used in wastewater treatment, ultrafiltration and microfiltration for general separation purposes, membrane distillation and rechargeable lithium batteries¹. To improve the selectivity of porous membranes, different carriers can be used in preparing. Dithiophosphates were synthesized according to the method described in literature². No work has been reported to date on microporous PVDF membranes containing dithiophosphates as carrier. In this work, microporous PVDF membranes containing dithiophosphates for Donnan dialysis application were prepared by freeze-gelation method³. To increase the efficiency of the microporous PVDF membranes and to improve their surface properties, they have been treated by Helicon plasma. The plasma treatment is a convenient technique for the chemical and physical modifications of polymer materials for improving the surface properties, such as wettability, adhesion and biocompatibility. To examine the effect of plasma treatment, the surface morphology of the plasma treatment and pristine membranes are characterized by SEM, AFM, FTIR-ATR and contact angle, respectively. In addition, both pristine and plasma treatment membranes were tested for some heavy metals removal by Donnan dialysis.