| 초록 |
Sulfonated polyimide (SPI) has been recently investigated as a potential proton exchange membrane to fulfill tough membrane criteria for fuel cell application owing to its easy fabrication, excellent thermal, chemical and mechanical stability. Especially, SPI is easily prepared through the polycondensation between dianhydrides and diamines where appropriate sulfonation degree, distribution of hydrophilic and hydrophobic domains, and consequent micro-phase separation can be simply achieved using sulfonated diamines. In this present study, comb-shaped sulfonated polyimide membranes were prepared by the introduction of aliphatic grafting agents (HO-(CH)n-SO3H, n = 2~4) containing additional sulfonic acid group. The effects of the negatively charged fixed ion in the side group on the proton conductivity and methanol permeability were observed in the membranes in relation to the water vapor sorption and ion exchange capacity. Eventually, they showed higher proton conductivity (＞ 9.2×10-2 S/cm at 95% RH and 60 oC) and much lower methanol permeability (＜ 2.38 cm2/sec) compared with Nafion 117 (6.2×10-2 S/cm and 1.64 cm2/sec, respectively). |
