This technology involves creating a cross-linker copolymer by introducing an imidazolium ionic liquid into the side chains of a rigid poly(arylene ether sulfone) block copolymer, then forming a cross-linked polymer membrane through a nucleophilic substitution reaction with a brominated block copolymer. The imidazolium group acts simultaneously as an ion conductor and a cross-linking site.
While membranes incorporating ionic liquids into polymers offer excellent ion conductivity, it has been extremely difficult to simultaneously achieve the dimensional and chemical stability required for fuel cell electrolyte membranes. A trade-off has persisted where increasing conductivity leads to membrane swelling, while increasing stability results in reduced conductivity.
This technology reacts 15 to 50 parts by weight of the ionic liquid cross-linker copolymer with 100 parts by weight of a brominated polymer, creating a network structure using the ionic groups themselves without a separate cross-linking agent. As a result, thermal, mechanical, and dimensional stability, as well as chemical stability under high pH conditions, are all improved. It can be applied not only to anion exchange membranes for alkaline fuel cells but also to gas separation membranes requiring CO2 selectivity, allowing a single membrane material to target both energy and carbon capture sectors.
This invention was developed with support from the Ministry of Education, Science and Technology for the development of high CO2-solubility ionic liquid-based membrane materials.
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