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Journal Articles

Preparation of polymer electrolyte membranes consisting of alkyl sulfonic acid for a fuel cell using radiation grafting and subsequent substitution/elimination reactions

Takahashi, Shuichi*; Okonogi, Hiroyuki*; Hagiwara, Tokio*; Maekawa, Yasunari

Journal of Membrane Science, 324(1-2), p.173 - 180, 2008/10

 Times Cited Count:37 Percentile:73.12(Engineering, Chemical)

Polymer electrolyte membranes (PEM) consisting of alkylsulfonic acid were successfully synthesized by radiation-induced graft polymerization of methyl acrylate (MA) into a poly(ethylene-co-tetrafluoroethylene) (ETFE) film, followed by sulfonation at an $$alpha$$-carbonyl carbon of the MA units in the grafting chain using an equimolar complex of chlorosulfonic acid and dioxane (ClSO$$_{3}$$H-Complex). The ion exchange capacity and ion conductivity of the MA-grafted PEM were controlled in the respective ranges of 0.54-1.47 mmol/g and 0.014-0.14 S/cm by changing the grafting degree. It has been confirmed by titrimetric and gravimetric analyses of sulfonic and carboxylic acids in the film that the sulfonation reaction is accompanied with decarboxylation of the MA units equimolar to the substituted sulfonic acids (substitution of carboxylic acid with sulfonic acid), that the sulfonation degree was about 30%.

Oral presentation

Novel electrolyte membranes synthesized by radiation graft polymerization and polymeric transformation of functional groups

Takahashi, Shuichi; Maekawa, Yasunari; Hagiwara, Tokio*; Okonogi, Hiroyuki*

no journal, , 

Aliphatic vinyl monomers, like acrylatic acid derivatives or vinyl ketones, were grafted by $$gamma$$-ray irradiation on a poly(ethylene-co-tetrafluoroethylene) (ETFE) film. Then, novel electrolyte membranes, which possess alkyl sulfonic acids on grafted chain, were synthesized by polymeric transformation of functional groups. The electrolyte membranes prepared by the above approach showed higher heat-stability in the wet condition compared to the electrolyte membranes with sulfonated styrene grafted membranes.

Oral presentation

Characterization of graft-type PEM prepared with the help of polymeric transformation of functional groups

Takahashi, Shuichi; Maekawa, Yasunari; Hagiwara, Tokio*; Okonogi, Hiroyuki*

no journal, , 

Methyl acrylate monomer was grafted by $$gamma$$-ray irradiation on a poly(ethylene-co-tetrafluoroethylene)(ETFE) film. Then, the novel polymer electrolyte membranes (PEM), which possess alkyl sulfonic acids on grafted chain, were synthesized by polymeric transformation of functional groups. The PEM prepared by the above approach were analyzed structurally and characterized well.

Oral presentation

Polymer electrolyte membranes consisting of alkyl sulfonic acid for fuel cells, synthesized by radiation-induced graft polymerization and subsequent chemical transformation

Maekawa, Yasunari; Takahashi, Shuichi; Hanh, T. T.*; Okonogi, Hiroyuki*; Hagiwara, Tokio*

no journal, , 

Polymer electrolyte membranes (PEMs) consisting of alkylsulfonic acid in grafting chains can be prepared by radiation-induced graft polymerization of methyl acrylate (MA) onto a poly(ethylene-co-tetrafluoroethylene) (ETFE) film, followed by the sulfonation of MA units in the grafting chains using an equimolar complex of chlorosulfonic acid and dioxane. The sulfonation reaction accompanied equimolar decarboxylation of the MA unit (substitution of carboxylic acid with sulfonic acid) to give the PEMs with conductivity of 0.01-0.11 S/cm. Furthermore, the replacement of the MA unit with methyl metacrylate (MMA) as a comonomer in grafting chains enhances the stability of the PEM at higher temperatures.

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