Tóm tắt: We have successfully synthesized highly porous polyimide film with tunable pore size, porosity and thickness, and used it as support matrix to construct Nafion infiltrated composite membrane. We have found a very efficient way for an easy and complete infiltration of the proton conducting polymer into this porous substrate, which is usually a big problem for preparing composite membranes. Due to the complete inertness to methanol and the very high mechanical strength of the porous polyimide matrix, the swelling of the composite membrane is greatly suppressed and the methanol crossover is also significantly reduced, while high proton conductivity and mechanical strength are still maintained. This membrane demonstrates significantly improved cell performance than Nafion membrane. Based on these results, Nafion/polyimide composite membrane has great potential to be used in direct methanol fuel cells.