Preparation and characterization of high selectivity organic–inorganic hybrid-laminated Nafion 115 membranes for DMFC

Commercially available Nafion 115 membranes were successfully modified by laminating the base membrane with high selectivity organic–inorganic hybrid materials, which consist of poly(ethylene glycol) as organic segment and silica as inorganic part. According to scanning electron microcopy (SEM) analysis, in the modified membranes, the base material was sandwiched between two hybrid layers. Silicon profiles across film thicknesses were analyzed via energy dispersive X-ray analysis (EDS). The roughness parameters obtained from atomic force microscopy (AFM) investigation were used to compare the surface morphology of the membranes. Thermogravimetric analysis (TGA) confirms the presence of hybrid materials in the laminated membranes. The water uptake increases as hybrid content increases. Methanol permeabilities in hybrid-laminated membranes were about an order of magnitude lower than Nafion 115, but the proton conductivity decreased only slightly at low hybrid content (13.6 wt.%). The selectivity (ratio of proton conductivity to methanol permeability) of hybrid-laminated membranes was much higher than that of Nafion 115, thereby promising for DMFC.