earticle

영어

In this study, a novel zwitterion-decorated lignin (ZL) containing amine and sulfonic acid groups was synthesized and ZL/Nafion composite membranes was fabricated to evaluate its effectiveness as a membrane additive. Kraft lignin was modified using amino-silane and 1,3-propanesultone by continuous grafting reaction to provide zwiterionic moieties structures. Chemical structural analyses confirmed the successful introduction of zwitterion moieties structure onto lignin. Especially, the surface charge of ZL was positive in acidic medium, and negative in basic medium, suggesting that ZL exhibited zwitterionic material. The ZL, an additive, was incorporated with the Nafion to enhance excellent ion exchange capacity and hydrophilicity. The proton conductivity of the ZL/Nafion is slightly lower than that of pure Nafion. On the other hand, it was confirmed that the addition of ZL in Nafion was significantly effective for proton conductivity compared to the addition of unmodified lignin. The reason is that the presence of amine groups in ZL can contribute to good dispersion and the presence of sulfonic acid groups preserves and further improves the continuity of the proton pathway inside the Nafion matrix. In addition, ZL may play a role in enhancing thermal stability, hydrophilicity, ion exchange capacity, and proton conductivity. Therefore, ZL is expected to be utilized as a multifunctional additive and has potential in fuel cell applications.