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A copolymer of poly[2,2′‐( m ‐phenylene)‐5,5′‐ bibenzimidazole] and poly(2,5‐benzimidazole) for high‐temperature proton‐conducting membranes
Author(s) -
Yang Jingshuai,
He Ronghuan,
Che Quantong,
Gao Xiaolei,
Shi Lili
Publication year - 2010
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2906
Subject(s) - copolymer , polymer chemistry , membrane , materials science , poly(p phenylene) , solubility , polymerization , phosphoric acid , thermogravimetric analysis , benzimidazole , conductivity , polymer , chemistry , organic chemistry , composite material , biochemistry , metallurgy
Abstract A novel copolymer of polybenzimidazoles was prepared by copolymerization of 3,3′‐diaminobenzidine tetrahydrochloride, 3,4‐diaminobenzoic acid and isophthalic acid in polyphosphoric acid at 200 °C. The polymerization could be performed within 90–110 min with the assistance of microwave irradiation. The solubility of the copolymer obtained in N , N ‐dimethylacetamide (DMAc) was improved compared with those of poly[2,2′‐( m ‐phenylene)‐5,5′‐bibenzimidazole] and poly(2,5‐benzimidazole). Thus copolymer membranes could be readily prepared by dissolving the copolymer powders in DMAc with refluxing under ambient pressure. The decomposition temperature of the copolymer was about 520 °C in air according to thermogravimetric analysis data. The proton conductivity and mechanical strength of the phosphoric acid‐doped copolymer membranes were investigated at elevated temperatures. A conductivity of 0.09 S cm −1 at 180 °C and a tensile stress at break of 5.9 MPa at 120 °C were achieved for the acid‐doped copolymer membranes by doping acids in a 75 wt% H 3 PO 4 solution. Copyright © 2010 Society of Chemical Industry