Preparation and characterization of proton-conducting crosslinked diblock copolymer membranes

Do Kyoung Lee, Yong Woo Kim, Jin Kyu Choi, Byoung Ryul Min, Jong Hak Kim

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Abstract

The synthesis and properties of crosslinked diblock copolymers for use as proton-conducting membranes are presented. A polystyrene-b-poly(hydroxyl ethyl methacrylate) diblock copolymer at 56: 44 wt % was sequentially synthesized via atom transfer radical polymerization. The poly(hydroxyl ethyl methacrylate) (PHEMA) block was thermally crosslinked by sulfosuccinic acid (SA) via the esterification reaction between -OH of PHEMA and -COOH of SA. Proton nuclear magnetic resonance and Fourier transfer infrared spectra revealed the successful synthesis of the diblock copolymer and the crosslinking reaction under the thermal condition of 120°C for 1 h. The ion-exchange capacity continuously increased from 0.25 to 0.98 mequiv/g with increasing SA concentration because of the increasing number of charged groups in the membrane. However, the water uptake increased up to an SAof 7.6 wt %, above which it decreased monotonically (maximum water uptake ∼ 27.6%). The membrane also exhibited a maximum proton conductivity of 0.045 S/cm at an SA concentration of 15.2 wt %. The maximum behavior of the water uptake and proton conductivity with respect to the SA concentration was considered to be due to a competitive effect between the increase of ionic sites and the crosslinking reaction according to the SA concentration. All the membranes were thermally quite stable at least up to 250°C, presumably because of the block-copolymer-based, crosslinked structure of the membranes.

Original languageEnglish
Pages (from-to)819-824
Number of pages6
JournalJournal of Applied Polymer Science
Volume107
Issue number2
DOIs
Publication statusPublished - 2008 Jan 15

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All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Surfaces, Coatings and Films
  • Polymers and Plastics
  • Materials Chemistry

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