M. Kawahara et al., Relationship between absorbed water and proton conductivity in sulfopropylated poly(benzimidazole), POLYM ADV T, 11(8-12), 2000, pp. 544-547
A novel proton-conducting polymer, sulfopropylated poly(benzimidazole) (PBI
-PS), was synthesized by the ring-opening reaction of I,3-propanesultone on
the reactive N-H groups of PBI. Cast pms of PBI-PS obtained from a dimethy
lsulfoxide solution of PBI-PS exhibited high water uptake, adequate mechani
cal strength, and flexibility. The temperature dependence of proton conduct
ivity for PBI-PS films hydrated at 90% R.H. showed high proton conductivity
of the order of 10(-3) Scm(-1) in the temperature range from room temperat
ure to 140 degreesC, which is superior to those of conventional proton cond
ucting polymers such as Nafion. The physical behavior of absorbed water in
hydrous PBI-PS pms was evaluated by differential scanning calorimetry (DSC)
, indicating that the absorbed water in PBI-PS mainly consisted of freezing
bound water. Copyright (C) 2000 John Wiley & Sons, Ltd.