Novel UV‐induced photografting process for preparing poly(tetrafluoroethylene)‐based proton‐conducting membranes |
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Authors: | Masaharu Asano Jinhua Chen Yasunari Maekawa Takahiro Sakamura Hitoshi Kubota Masaru Yoshida |
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Institution: | 1. Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki‐Machi, Takasaki, Gunma 370‐1292, Japan;2. Environment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki‐Machi, Takasaki, Gunma 370‐1292, JapanEnvironment and Industrial Materials Research Division, Quantum Beam Science Directorate, Japan Atomic Energy Agency, 1233 Watanuki‐Machi, Takasaki, Gunma 370‐1292, Japan;3. Department of Chemistry, Faculty of Engineering, Gunma University, 1‐5‐1 Tenjin‐Cho, Kiryu, Gunma 376‐8515, Japan |
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Abstract: | A novel process comprising the UV‐induced photografting of styrene into poly(tetrafluoroethylene) (PTFE) films and subsequent sulfonation has been developed for preparing proton‐conducting membranes. Although under UV irradiation the initial radicals were mainly generated on the surface of the PTFE films by the action of photosensitizers such as xanthone and benzoyl peroxide, the graft chains were readily propagated into the PTFE films. The sulfonation of the grafted films was performed in a chlorosulfonic acid solution. Fourier transform infrared and scanning electron microscopy were used to characterize the grafted and sulfonated membranes. With a view to use in fuel cells, the proton conductivity, water uptake, and mechanical properties of the prepared membranes were measured. Even through the degree of grafting was lower than 10%, the proton conductivity in the thickness direction of the newly prepared membranes could reach a value similar to that of a Nafion membrane. In comparison with γ‐ray radiation grafting, UV‐induced photografting is very simple and safe and is less damaging to the membranes because significant degradation of the PTFE main chains can be avoided. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2624–2637, 2007 |
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Keywords: | conducting polymers FT‐IR functionalization of polymers graft polymers irradiation photografting photopolymerization poly(tetrafluoroethylene) (PTFE) proton‐conducting membranes |
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