Highly reinforced pore-filling membranes based on sulfonated poly(arylene ether sulfone)s for high-temperature/low-humidity polymer electrolyte membrane fuel cells

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>A series of pore-filling membranes are prepared by impregnating porous cross-linked benzoxazine-benzimidazole copolymer P(<I>p</I>BUa-<I>co</I>-BI) substrates with sulfonated poly(arylene ether sulfone)s (SPAES)s having different degree of sulfonation for polymer electrolyte membrane fuel cells operating at high-temperatures (>100°C) and low-humidity (<50% RH) conditions. The SPAESs are synthesized by reacting 4,4’-dihydroxybiphenyl with the mixtures of disulfonate-4,4’-difluorodiphenylsulfone and 4,4’-difluorodiphenylsulfone in different ratios. The porous P(<I>p</I>BUa-<I>co</I>-BI) substrates are prepared by extracting dibutyl phthalate (DBP) included in P(<I>p</I>BUa-<I>co</I>-BI) films using methanol. The P(<I>p</I>BUa-<I>co</I>-BI) films are prepared by stepwise heating the casted <I>N,N-</I>dimethylacetamide solution containing the mixtures of poly[2,2′-(<I>m</I>-phenylene)-5,5′-bibenzimidazole] (PBI), 3-phenyl-3,4- dihydro-6-<I>tert</I>-butyl-2<I>H</I>-1,3-benzoxazine (<I>p</I>BUa), and DBP to 220°C. The pore-filling membranes are found to have much improved dimensional stability and mechanical strength compared with the SPAES membranes. Although the proton conductivity values of the pore-filling membranes are slightly smaller than those of the SPAES membrane, their cell performance is superior to that of the SPAES membrane at 120°C and 40% RH conditions because ultrathin pore-filling membranes (15–20µm) having high mechanical strength can be prepared and they can contain a larger content of chemically-bound water.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SPAESs having different degree of sulfonation were synthesized as pore-filling polymers. </LI> <LI> Transparent, ultrathin, and highly-flexible pore-filling membranes were developed. </LI> <LI> Acid-base interaction between the porous substrate and filling SPAES was found. </LI> <LI> Excellent physical stability and mechanical strength of the pore-filling membranes. </LI> <LI> Cell performances of MEAs from the pore-filling membranes were highly improved. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>