| Abstract
| - The structure of proton transport channels is controlled and fixed in sulfonated poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymer membranes. Microphase-separated SBS membranes werecross-linked by UV irradiation in the presence of a photoinitiator and then sulfonated by acetyl sulfate.Sulfonated cross-linked SBS (scSBS) membranes with fixed nanosized proton transport channels werethen prepared. The scSBS membranes show good proton conductivity, comparable to that of Nafion, anda low methanol permeability, more than 1 order of magnitude smaller than that of Nafion. Sulfonatednon-cross-linkable poly(styrene-b-(ethylene-r-butylene)-b-styrene) membranes and sulfonated cross-linkedpoly(styrene-r-butadiene) membranes, which have less developed proton transport channels, were alsoprepared for comparison. The effects of the presence and size of the proton transport channels on theproton conductivity and methanol permeability were investigated. It is concluded that both the structureand the fixation of the proton transport channels are crucial to the functioning of proton exchangemembranes of direct methanol fuel cells.
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