A series of sulfonated polyimide copolymers as novel proton exchange materials were synthesized by the polycondensation of 1

4

5

8-naphthalene-tetracarboxylic dianhydride (NTDA)

sulfonated diamine based on pyridine group and diamine containing

N

-phenyl-1

2

4-triazole moiety. Flexible

transparent and tough membranes with high thermal stability and good mechanical properties were obtained. They exhibited good stability in boiling water and Fenton’s reagent at 80 ℃. More interestingly

a nonlinear relationship between proton conductivities of the resulting membranes and the degree of sulfonation (DS) was observed. The membrane with 50% DS exhibited the maximum proton conductivity

which was due to the combinational contributions of sulfonic acid and

N

-pheny-1

2

4-triazole groups. Thus

the

N

-phenyl-1

2

4-triazole moiety in this study not only can depress water absorption but also increase proton conductivity

especially at low DS.