Electrical conductivity responses and interactions of poly(3-thiopheneacetic acid)/zeolites L, mordenite, beta and H2

Abstract Poly(3-thiopheneacetic acid), P3TAA, was chemically synthesized via an oxidation polymerization and doped with perchloric acid. Composites were fabricated from P3TAA and zeolites, zeolites L (L), mordenite (MOR), and beta (BEA) through random dry mixing. The electrical conductivity response toward H 2 was investigated for the effects of zeolite contents, zeolite type, cation type, and cation concentration. Negative electrical conductivity response and sensitivity generally occur when exposed to H 2 relative to N 2 . A weaker interaction is suggested to occur between H 2 and the polaron or the bipolaron species relative to the interaction between N 2 and active sites of the doped P3TAA. For the effect of zeolite content, the composite with 20% (v/v) MOR has the highest electrical conductivity sensitivity value. The reduction of sensitivity values occurs with increasing MOR zeolite concentration from 20 to 50% (v/v); this arises from the diminishing active sites available for the interaction between H 2 and the polaron or the bipolaron species. For the composites with 20% (v/v) L, MOR and BEA, the electrical conductivity sensitivity increases with decreasing Al content because of a lesser interaction between H 2 and the zeolite, and consequently a greater interaction between H 2 and the active sites on the polymer chain. The higher electronegativity and smaller ionic radius of Li + loaded into the MOR zeolite framework causes the lowering of electrical conductivity sensitivity than the composites loaded with Na + and K + . For composites with zeolite L loaded with Na + at 0, 15, 20, 30 and 50 mole%, the electrical conductivity sensitivity increases with increasing Na + content up to 30 mole% and decreases beyond that.

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