Semi-interpenetrating Polymer Network Membranes of Poly(arylene ether sulfone) for Direct Methanol Fuel Cell

Abstract

In order to retain the proton conductivity and reduce the methanol crossover in the direct methanol fuel cell (DMFC), the semi-IPN membranes composed of hydrophilic component as proton conduction and hydrophobic component as methanol barrier were prepared. Acrylate-terminated fully sulfonated poly(arylene ether sulfone) oligomers (acPAES-100) with tetrabutylammonium ion were synthesized for the proton conducting component. As methanol barrier, poly(ether sulfone) copolymers (RH-2000, Solvay) were used. In the blended system, the introduction of hydrophilic component with low molecular weight and low hydrophilicity made it possible to form the boundary of the phase separation at the low concentration of the solvent in the phase diagram and to restrict the phase separation of semi IPN membranes. The blend ratio of acPAES-100 (ammonium form) and RH-2000 was prepared by the weight ratio of 5:5 and 7:3. Through applying the different drying conditions (HT1, HT2, HT3 and HT4) and UV-curing process, the semi-IPN membranes with phase separated morphologies could be obtained. The morphology of semi-IPN membranes was investigated by FE-SEM and TM-AFM. The transport properties such as proton conductivity and methanol permeability were measured by the AC impedance spectroscopy and the liquid permeability measuring instrument, respectively. The DMFC membrane properties such as water uptake, proton conductivity and methanol permeability were influenced on the morphology of semi-IPN membranes. In this thesis, the effect of the drying condition on the phase separation and the morphology were investigated and then transport properties of semi-IPN membranes were discussed.