Acidic liquid-swollen polymer membranes exhibiting anhydrous proton conductivity higher than 100 mS cm−1 at around 100 °C

Abstract

Anhydrous proton-conductive membranes are prepared by incorporating sulfuric acid (H₂SO₄) into cross-linked poly(4-vinylpyridine) (CL-P), where H₂SO₄ mixes CL-P homogeneously at the molecular level, and therefore incorporated H₂SO₄ does not leach out from CL-P, even when the weight ratio of H₂SO₄ to CL-P is about four. The membranes are soft but self-standing and exhibit anhydrous conductivity higher than 100 mS cm⁻¹ at around 100 °C. Furthermore, a membrane composed of polystyrene-b-poly(4-vinylpyridine)-b-polystyrene triblock copolymers and H₂SO₄ achieves not only high anhydrous conductivity but also good mechanical properties as a membrane.