Preparation and Properties of Sulfonated or Phosphonated Polybenzimidazoles and Polybenzoxazoles

Sakaguchi, Yoshimitsu; Kitamura, Kota; Nakao, Junko; Hamamoto, Shiro; Tachimori, Hiroshi; Takase, Satoshi

doi:10.1007/0-306-47563-4_8

Cited by 15 publications

(16 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The most common PEMs are perfluorosulfonate ionomers,47 but considerable contemporary ionomer research has focused on the development of sulfonated hydrocarbon polymers as substitutes for the relatively expensive perfluorosulfonates 48–51. Phosphonate ionomers have also been studied for PEM applications,52–59 but that represents only a relatively small part of the materials development for PEMs conducted over the past decade. In the present study, the styrene–phosphonate ionomers were evaluated for their applicability as PEMs.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of poly (styrene‐co‐vinyl phosphonate) ionomers

Weiß

2004

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

Poly(styrene‐co‐diethyl vinylphosphonate) copolymers were synthesized by free radical copolymerization. The ester groups of the copolymers were hydrolyzed to phosphonic acid groups, and the sodium and zinc salts ionomers were obtained by neutralization. The structure and the thermal and viscoelastic properties of the copolymers and ionomers were characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, differential scanning calorimetry, dynamic mechanical analysis, and small‐angle X‐ray scattering. The phosphonate ester lowered the glass transition temperature (Tg) of polystyrene. The free acid derivatives and metal phosphonates increased Tg and produced a rubbery plateau region in the viscoelastic properties due to the formation of a physical network. The acid and salt ionomers exhibited microphase‐separated morphologies and were thermorheologically complex. The phosphonic acid derivatives absorbed relatively little water, even for materials with ion‐exchange capacities greater than 1.0 mEq/g, and were not conductive, which made them unsuitable for application as proton exchange membranes. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3628–3641, 2004

show abstract

Section: Resultsmentioning

confidence: 99%

Synthesis and characterization of poly (styrene‐co‐vinyl phosphonate) ionomers

Weiß

2004

J Polym Sci B Polym Phys

View full text Add to dashboard Cite

show abstract

“…13,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] Three common approaches are typically employed for functionalizing PBI: (1) direct sulfonation of the backbone, 29,47,49 (2)chemical grafting of functionalized monomers, 31,35 or (3) polycondensation of a sulfonated aromatic diacid with an aromatic tetraamine. 30,50 The last method provides advantages over the first two, such as limitation of side reactions and control over the degree of sulfonation. Previously published work has focused on modification of the m-PBI backbone structure.…”

Section: Introductionmentioning

confidence: 99%

Sulfonated Polybenzimidazoles for High Temperature PEM Fuel Cells

2010

View full text Add to dashboard Cite

High molecular weight, highly PA-doped s-PBI membranes have been developed with robust mechanical properties and excellent proton conductivities (>0.1 S cm -1 ) at elevated temperatures (>100°C). These membranes show high PA loadings of 30-35 mol PA/PBI, and average tensile stress and strain of 0.804 MPa and 69.64%, respectively. Proton conductivities were dependent on the acid doping level and measured between 0.1 and 0.25 S cm -1 at 180°C, a pronounced increase over most phosphoric acid-doped sulfonated PBI membranes to date. Preliminary fuel cell testing with hydrogen fuel and air or oxygen oxidants was performed at temperatures greater than 100°C without external feed gas humidification and show excellent performance (0.62-0.68 V at 0.2 A cm -2 and 160°C, hydrogen/air; 0.69-0.76 V at 0.2 A cm -2 and 160°C, hydrogen/oxygen). Initial performance stability studies were conducted for ∼3000 h and indicate great promise as high temperature membranes, with a degradation rate of 30 μV h -1 .

show abstract

“…Sulfonated polybenzoxazoles were prepared from 5-sulfoisophthalic or 2-sulfoterephthalic acids and different bis-(o-aminophenols) [159].…”

Section: Scheme 18mentioning

confidence: 99%