A novel organic/inorganic polymer membrane based on poly(vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid/3-glycidyloxypropyl trimethoxysilane polymer electrolyte membrane for direct methanol fuel cells

Poly(vinyl alcohol)/poly(2-acrylamido-2-methyl-1-propanesulfonic acid (PAMPS)/3-glycidyloxypropyl)trimethoxysilane (PVA/PAMPS/GPTMS) organic/inorganic proton-conducting polymer membranes are prepared by a solution casting method. PAMPS is a polymeric acid commonly used as a primary proton donor, while 3-(glycidyloxypropyl)trimethoxysilane (GPTMS) is an inorganic precursor forming a semi-interpenetrating network (SIPN). Varying amounts of sulfosuccinic acid (SSA) are used as the cross-linker and secondary proton source. The characteristic properties of PVA/PAMPS/GPTMS composite membranes are investigated by thermal gravimetric analysis (TGA), scanning electron microscopy (SEM), micro-Raman spectroscopy and the AC impedance method. Direct methanol fuel cells (DMFCs) made of PVA/PAMPS/GPTMS composite membranes are assembled and examined. Experimental results indicate that DMFCs employing an inexpensive, non-perfluorinated, organic/inorganic SIPN membrane achieve good electrochemical performance. The highest peak power density of a DMFC using PVA/PAMPS/GPTMS composite membrane with 2 M CH₃OH solution fuel at ambient temperature is 23.63 mW cm^-2. The proposed organic/inorganic proton-conducting membrane based on PVA/PAMPS/GPTMS appears to be a viable candidate for future DMFC applications.