NAMS 2002 Workshop - ICOM 2008

Fuel Cells I – 3
Monday July 14, 3:30 PM-4:00 PM, Honolulu/Kahuku
Proton Conducting Graft Copolymer Electrolyte Membranes for Fuel Cells
J. Koh, Yonsei University, Seoul, Korea
J. Park, Yonsei University, Seoul, Korea
D. Roh, Yonsei University, Seoul, Korea
J. Kim (Speaker), Yonsei University, Seoul, Korea, jonghak@yonsei.ac.kr
A series of proton conducting comb copolymer membranes consisting of
poly(vinylidene fluoride- co-chlorotrifluoroethylene) backbone and poly (styrene
sulfonic acid) side chains, i.e. P(VDF- co-CTFE)-g-PSSA were synthesized using
atom transfer radical polymerization (ATRP). 1H NMR, FT-IR spectroscopy, wide
angle X-ray scattering (WAXS) and transmission electron microscopy (TEM)
results present the successful ‘grafting from’ method using ATRP and the welldefined
microphase-separated structure of the polymer electrolyte membranes.
All the properties of ion exchange capacity (IEC), water uptake and proton
conductivity for the membranes continuously increased with increasing PSSA
contents. The results of thermal gravimetric analysis (TGA) also showed that all
the membranes were stable up to 300 o C. After terminated chlorine atoms were
converted to end-functional azide groups (P (VDF-co-CTFE)-g-PSSA-N3), the
polymer electrolyte membranes were crosslinked under UV irradiation. The
crosslinked P(VDF-co-CTFE)-g- PSSA membrane with 73 wt% of PSSA content
exhibited the reduced water uptake from 300 to 83 %, the increased tensile
strength from 21.1 to 26.2 MPa and the slightly reduced proton conductivity from
0.074 to 0.068 S/cm at room temperature compared to the uncrosslinked
membrane.