Sulfonic acid Sulfone을 포함한 m-Aramid계 Ionomer의 합성과 연료전지 막으로의 이용

Abstract

본 연구에서는 연료전지용 수소 이온 교환막으로 사용하기 위해서 축합 중합법을 이용하여 sulfonic acid ether sulfone을 포함하는 meta aramid 공중합체를 합성하였으며 공중합체 양 말단의 amine기를 acryloyl기로 치환하였다. Acryl기 함유 전구체는 열 가교를 통해 고분자 전해질 막으로 제조되었으며, 막의 성질에 대해서 연구하였다. 이 이온 교환막의 열적 특성을 측정해 본 결과, 380 oC까지 열적으로 안정한 것을 확인하였다. 이온 교환막의 함수율은 가교되지 않은 랜덤공중합체보다 낮은 수치를 보였고 이온 교환 용량, 수소 이온 전도도는 sulfonated ether sulfone 함량의 증가에 따라서 증가하였다. 함수율은 44 wt%보다 낮은 수치를 보였으며, 가장 높은 수소 이온 전도도의 값은 상대습도 100%, 25 oC에서 3.93 x 10-2 S/cm 였다.; Aromatic copolyamides were prepared and their applicability to proton exchange membrane was studied. The copolymer contains thermally stable and mechanically strong poly(m-phenylene isophthalamide) segments, and easily processable and good film forming polysulfone segments. For the copolymer, amine-terminated sulfonated ether sulfone monomer, m-phenylene diamine, and isophthaloyl chloride were reacted, and the obtained copolymer was transformed into crosslinkable prepolymer by the reaction with acryloyl chloride. The prepolymer was thermally cured and converted into proton exchange membranes for fuel cell application. Each reaction step and the molecular characteristics of precursor copolymers were followed and confirmed by 1H-NMR, FT-IR, and titration. The performance of the membranes was measured in terms of water uptake, proton conductivity, and thermal stability. The water uptake, ion exchange capacity (IEC), and proton conductivity of the membranes increased with the increase of sulfonated ether sulfone segment content. Membrane containing 30 mol% sulfonic acid sulfone segment showed 1.57 meq/g IEC value. Water uptake was limited less than 44 wt% and the highest proton conductivity was up to 3.93 x 10-2 S/cm (25 oC, RH=100%).