Kinetics of poly(ethylene glycol) extraction into water from plasticized disulfonated poly(arylene ether sulfone) desalination membranes prepared by solvent-free melt processing

Disulfonated poly(arylene ether sulfone)s (BPS) random copolymers have been used as membranes for purifying water and generating electricity. These membranes can be prepared by solvent-free, melt extrusion using a proper plasticizer. Poly(ethylene glycol), PEG, materials are used as plasticizers to extrude thin, single layer BPS membranes and need to be extracted from the films before their use as membranes. Since PEG materials are water soluble, they can, in principle, be water extracted after melt extrusion. Experimental and theoretical studies of several factors influencing the diffusion of PEG from these films are needed in order to optimize this route to membrane preparation. The rate of PEG extraction is affected by the molecular weight (M̅_n) and concentration (wt%) of PEG in the extruded BPS-20K/PEG films, as well as the temperature. When the early time approximation and complete solution of a Fickian model were used to analyze the kinetic desorption of PEG materials from the extruded films, they were found to describe the data. The diffusion coefficients of the PEG materials determined from this analysis correlated well with temperature and follow the Arrhenius equation.