Proton conductivity and methanol transport behavior of cross-linked PVA/PAA/silica hybrid membranes

Kim, Dae Sik; Park, Ho Bum; Rhim, Ji Won; Lee, Young Moo

doi:10.1016/j.ssi.2004.07.011

Cited by 223 publications

(130 citation statements)

References 22 publications

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“…SP/SA-SNP shows the highest bound water/total water ratio among the three examined membranes. The effect of SA-SNP on water content introduces two contradictory aspects: (i) a hygroscopic effect [53] due to the nanocomposite membrane possessing sites that can absorb water, those being both the silica particles and the sulfonic acid groups, which act to increase the content of bound water; (ii) a cross-linking effect due to the inorganic network [23], which reduces polymer chain mobility (free volume) and the space where absorbed water can be accommodated, especially in the case of SA-SNP that gives rise to a more rigid and compact polymer structure. Therefore, with the addition of SA-SNP, the cross-linking effect is more prominent than the hygroscopic effect.…”

Section: The State Of Water In the Membranementioning

confidence: 99%

“…Sulfonic acid groups were incorporated onto the resulting inorganic material after oxidation of the -SH groups of MPDMS. Kim et al reported similar work on PVA/poly(acrylic acid) based PEMs [23]. Rhee et al [24] utilized sulfonated montmorillonite to modify Nafion ® to effectively lower the methanol crossover without decreasing PEM proton conductivities.…”

Section: Introductionmentioning

confidence: 97%

“…The concept of using inorganic reinforcements possessing sulfonic acid groups has been explored to compensate for the decreases in the sulfonic acid concentrations when normally nonsulfonated inorganic materials are used to form nanocomposite PEMs [22][23][24]. Nagarale et al [22] prepared poly(vinyl alcohol) hybrid membranes using tetraethyl orthosilicate (TEOS) and mercaptopropylmethyldimethoxysilane (MPDMS) as precursors via sol-gel reactions.…”

Section: Introductionmentioning

confidence: 99%

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Increases in the proton conductivity and selectivity of proton exchange membranes for direct methanol fuel cells by formation of nanocomposites having proton conducting channels

Liu

Wang

et al. 2009

Journal of Power Sources

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We explore an approach to effectively enhance the properties of cost-effective hydrocarbon protonexchange membranes for application in the direct methanol fuel cell (DMFC). This approach utilizes sulfonated silica nanoparticles (SA-SNP) as additives to modify sulfonated poly(arylene ether ether ketone ketone) (SPAEEKK). The interaction between the sulfonic acid groups of SA-SNP and those of SPAEEKK combined with hydrophilic-hydrophobic phase separation induce the formation of proton conducting channels, as evidenced by TEM images, which contribute to increases in the proton conductivity of the SPAEEKK/SA-SNP nanocomposite membrane. The presence of SA-SNP nanoparticles also reduces methanol crossover in the membrane. Therefore, the SPAEEKK/SA-SNP nanocomposite membrane shows a high selectivity, which is 2.79-fold the selectivity of Nafion ® 117. The improved selectivity of the SPAEEKK/SNP nanocomposite membrane demonstrates potential of this approach in providing hydrocarbon-based PEMs as alternatives to Nafion in direct methanol fuel cells.

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Section: The State Of Water In the Membranementioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Increases in the proton conductivity and selectivity of proton exchange membranes for direct methanol fuel cells by formation of nanocomposites having proton conducting channels

Liu

Wang

et al. 2009

Journal of Power Sources

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“…Sistemas de materiais híbridos, composto por uma fase orgânica e outra inorgânica, são promissores em muitos campos de aplicação tecnológica, devido ao sinergismo apresentado por esses compostos [9][10][11][12][13] .…”

Section: Introductionunclassified

Membranas de PVA e sílica para aplicação em célula a combustível de alimentação direta de álcool

2014

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Resumo: Membranas de PVA/sílica foram sintetizadas através do processo sol-gel em condições ácidas. Tetraetilortossilicato (TEOS) foi utilizado como precursor em concentrações de 5 a 30% em dois grupos distintos. Um grupo foi utilizado como controle contendo apenas PVA/TEOS. A inserção dos grupamentos necessários para a condutividade ocorreu através da introdução de 12% em massa de heteropoliácido fosfotúngstico hidratado (HPW) em relação à massa de TEOS, formando o segundo grupo. As avaliações quanto ao grau de inchamento, permeabilidade ao etanol e condutividade protônica demonstraram que a membrana contendo 30% em massa de TEOS apresenta os melhores resultados entre as membranas produzidas. Os melhores resultados foram 0,28 mS/cm de condutividade protônica e fluxo de 1,5 kg/m².h de solução de etanol. Nessas condições, considera-se a reticulação das membranas de PVA/SiO 2 com o precursor TEOS uma boa alternativa para a reticulação de membranas de PVA visto que as membranas mostraram-se mais seletivas ao fluxo de solução de etanol. Entretanto, para aplicação como eletrólito de célula a combustível, ainda é necessário investigar outras formas de aumentar a condutividade sem prejudicar a estabilidade dimensional. Palavras-chave: PVA, célula a combustível, HPW, sílica, membranas condutoras de prótons. Membranes of PVA and Silica for Application in Direct Alcohol Fuel CellAbstract: PVA/silica membranes were synthesized by the sol-gel process under acidic conditions. Tetraethoxysilane (TEOS) was used as precursor with concentration between 5 and 30% in two distinct systems. One system was used as control, which contained only PVA / TEOS. In the second system, groups necessary for conductivity were introduced with 12% by weight of hydrated phosphotungstic heteropolyacid (HPW) in relation to the mass of TEOS. The evaluations of the degree of swelling, permeability for ethanol and proton conductivity have shown that the membrane containing 30 wt% TEOS gives the best results among the membranes produced. The best results achieved in this study were 0.28 mS / cm of proton conductivity and 1.5 kg/m².h flux of ethanol solution. Thus, under these conditions, crosslinked membranes with PVA/SiO2 and TEOS precursor are good alternative for crosslinking PVA membranes since they were more selective to the flow of ethanol solution. However, for applications such as in electrolyte fuel cells, it is still necessary to investigate other ways to increase conductivity without affecting the dimensional stability. Keywords IntroduçãoCélula a combustível (FC) que utiliza membrana polimérica condutora de prótons tem despertado bastante interesse ao longo dos anos devido ao seu baixo potencial poluidor e à larga gama de aplicação como em veículos e dispositivos portáteis [1][2][3] .Tradicionalmente o Nafion, copolímero sulfonado perfluorado, é o mais utilizado em FC, entretanto apresenta o inconveniente do fenômeno de metanol crossover. Além desse problema técnico, o fato de ser um polímero caro motiva a busca por membranas alternativas [...

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“…Thus, crosslinking has been used as a good solution to maintain a proper sulfonation level and to enhance the mechanical properties. [10][11][12] There have been many attempts to develop crosslinked sulfonated polymer membranes using polyimide, 13 poly(vinyl alcohol), 14 and poly(2,6-dimethyl-1,4-phenylene oxide). 15 Use of self-organized, nanophase-separated structure can allow for a better control of both the sulfonation degree and the distribution of sulfonic acid groups in the sulfonated polymer membranes.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of crosslinked polystyrene-b-poly(hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid) triblock copolymer for electrolyte membranes

et al. 2009

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Abstract:The synthesis and the characterization of crosslinked ABC triblock copolymer, i.e. polystyrene-b-poly (hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid), (PS-b-PHEMA-b-PSSA) is reported. PS-b-PHEMA-b-PSSA triblock copolymer at 20:10:70 wt% was sequentially synthesized via atom transfer radical polymerization (ATRP). The middle block was crosslinked by sulfosuccinic acid (SA) via the esterification reaction between -OH of PHEMA and -COOH of SA, as demonstrated by FTIR spectroscopy. As increasing amounts of SA, ion exchange capacity (IEC) continuously increased from 2.13 to 2.82 meq/g but water uptake decreased from 181.8 to 82.7%, resulting from the competitive effect between crosslinked structure and the increasing concentration of sulfonic acid group. A maximum proton conductivity of crosslinked triblock copolymer membrane at room temperature reached up to 0.198 S/cm at 3.8 w% of SA, which was more than two-fold higher than that of Nafion 117(0.08 S/cm). Transmission electron microscopy (TEM) analysis clearly showed that the PS-b-PHEMA-b-PSSA triblock copolymer is microphase-separated with a nanometer range and well developed to provide the connectivity of ionic PSSA domains. The membranes exhibited the good thermal properties up to 250 o C presumably resulting from the microphase-separated and crosslinked structure of the membranes, as revealed by thermal gravimetric analysis (TGA).

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Proton conductivity and methanol transport behavior of cross-linked PVA/PAA/silica hybrid membranes

Cited by 223 publications

References 22 publications

Increases in the proton conductivity and selectivity of proton exchange membranes for direct methanol fuel cells by formation of nanocomposites having proton conducting channels

Increases in the proton conductivity and selectivity of proton exchange membranes for direct methanol fuel cells by formation of nanocomposites having proton conducting channels

Membranas de PVA e sílica para aplicação em célula a combustível de alimentação direta de álcool

Synthesis of crosslinked polystyrene-b-poly(hydroxyethyl methacrylate)-b-poly(styrene sulfonic acid) triblock copolymer for electrolyte membranes

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