| 초록 |
Poly[(2,5-benzimidazole)-co-(2,2’-(p-phenylene)-5,5’-bibenzimidazole)]s(AB-pPBI-Xs, where X is mol% of 3,4-diaminobenzoic acid) were syntheiszed by condensation polymerization of 3,4-diaminobenzoic acid and terephthalic acid with 3,3’-diaminobenzidine in polyphosphoric acid(PPA) at 240oC. We varied the feed ratio of terephthalic acid from 10 to 50mol% to study the effect of rigid p-phenylene moieties on physical and electrochemical properties of polybenzimidazoles systematically. AB-pPBI-Xs show reduced crystallinity by WAXS measurements, compared to poly(2,5-benzimidazole)(ABPBI) and poly[2,2’-(p-phenylene)-5,5’-bibenzimidazole](pPBI) membranes. They exhibit high proton conductivity compared to commercial PBI, poly[2,2’-(m-phenylene)-5,5’-bibenzimidazole](mPBI). Particularly, AB-pPBI-80 membrane maintains high mechanical property, tensile strength of 27MPa at 24oC and 25%RH, even at high acid doping level |
