Characterization of poly(vinylchloride) (PVC) based cation exchange membranes prepared with ionic liquid

Abstract

In this study, poly(vinylchloride) (PVC) based heterogenous strong acidic cation exchange membranes were prepared by the solution casting technique by using suspension polymerized polyvinylchloride (S-PVC) and emulsion polymerized polyvinylchloride (E-PVC) as binders, dioctyl phthalate (DOP) and ionic liquid (IL) tetradecyl(trihexyl)phosphoniumdecanoate as plasticizers and ion exchange resin as functional group agent. The main goal of this work was to evaluate the effects of polymer binder type, plasticizer type and bider/plasticizer ratio on pyhsicochemical, morphological and electrochemical properties of the prepared membranes. Physicochemical characterization consisted of water contents, dry and wet densities, porosities, ion exchange capacities of membranes and isotherm studies. Scanning Electron Microscopy (SEM) analysis was used to perform morphological characterization. Water contents of the membranes were found between 30% and 40% while density values were in the 0.7–1.2g/cm3 range. Porosities were found between 0.2 and 0.4 and ion exchange capacities changed between 1.2 and 2.8meq Na+/g-dry. Electrochemical characterization included transport numbers of membranes determined by the membrane potential method. Transport number for the membranes prepared with dioctyl phthalate (DOP) was found to be around 0.5 whereas this figure was 1.0 for the membranes prepared with IL. Diffusivity values of Na+ ions across the membrane were calculated by using the Donnan dialysis method and found in order of magnitude-5.