Influence of the polymer backbone structure on the properties of aromatic ionomers with pendant sulfobenzoyl side chains for use as proton-exchange membranes

Summary, in English

Six different ionomers having various aromatic polymer backbones with pendant 2-sulfobenzoyl side chains were prepared by nucleophilic aromatic substitution reactions of lithium 2,6-difluoro-2′-sulfobenzophenone with 4,4-biphenol, 2,7-dihydroxynaphthalene, 4,4-isopropylidenediphenol, 4,4-dihydroxydiphenyl ether, 4,4′-thiodiphenol, and 4,4′-thiobisbenzenethiol, respectively, to produce four poly(arylene ether)s, one poly(arylene ether sulfide), and one poly(arylene sulfide). Mechanically tough proton-exchange membranes with ion-exchange capacities in the narrow range from 1.9 to 2.3 mequiv/g were cast from the high-molecular-weight ionomers, and subsequently investigated with respect to their structure−property relationships. Glass transitions were only detected for ionomers in the sodium salt form, and increasing glass-transition temperatures (Tg) were found to give higher thermal decomposition temperatures. Analysis by small-angle X-ray scattering indicated that the ionic clustering was promoted for ionomers with flexible polymer backbones and low Tg values. The proton conductivity of the membranes at 80 °C under fully humidified conditions was found between 0.02 and 0.2 S/cm and appeared to depend primarily on the Tg.

• Author: Elin Persson Jutemar; Patric Jannasch
• Department/s: Centre for Analysis and Synthesis
• Publishing year: 2010
• Language: English
• Pages: 3718-3725
• Publication/Series: ACS Applied Materials and Interfaces
• Volume: 2
• Issue: 12
• Links: http://pubs.acs.org/doi/abs/10.1021/am1008612; http://dx.doi.org/10.1021/am1008612
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Chemical Sciences
• Keywords: SAXS; proton-exchange membrane fuel cells; sulfonated polymer electrolytes; polycondensations; polyaromatics
• Status: Published
• ISBN/ISSN/Other: ISSN: 1944-8244