The direct synthesis of wholly aromatic poly( p-phenylene)s bearing sulfobenzoyl side groups as proton exchange membranes

• Published in: Polymer (Guilford) Vol. 47; no. 20; pp. 6993 - 7000
• Main Authors: Wu, Shuqing, Qiu, Zhiming, Zhang, Suobo, Yang, Xiurong, Yang, Fan, Li, Zhiying
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 20.09.2006; Elsevier
• Subjects: Applied sciences; Copolymerization; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Polymers with particular properties; Preparation, kinetics, thermodynamics, mechanism and catalysts; Proton exchange membrane; Sulfonated poly( p-phenylene)s; Proton exchange membrane; Copolymerization; Sulfonated poly( p-phenylene)s; Benzophenone derivatives; Transport properties; Temperature effect; Polymer solid electrolyte; Sulfonate copolymer; Oxidation resistance; Proton conductivity; Aromatic copolymer; Water absorption; Chemical properties; Methanol; Phenylene derivative copolymer; Electrical properties; Solution polycondensation; Sulfonated poly(p-phenylene)s; Mechanical properties; Tensile property; Experimental study; Functional polymer; Gas permeability; Cation exchange capacity; Morphology; Preparation; Cation exchange membrane; Soluble compound; Liquid permeability
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2006.08.017

Sulfonated poly( p-phenylene)s ( SPPs) containing sulfonic acid groups in their side chains had been directly synthesized by Ni(0) catalytic coupling of sodium 3-(2,5-dichlorobenzoyl)benzenesulfonate and 2,5-dichlorobenzophenone. The synthesized copolymers possessed high molecular weights revealed by their high viscosity, and the formation of tough and flexible membranes by casting from DMAc solution. The copolymers exhibited excellent oxidative stability and mechanical properties due to their fully aromatic structure extending through the backbone and pendent groups. Transmission electron microscopic (TEM) analysis revealed that these side-chain type SPP membranes have a microphase-separated structure composed of hydrophilic side-chain domains and hydrophobic polyphenylene main chain domains. The proton conductivities of copolymer membranes increased with the increase of IEC and temperature, reaching values above 3.4 × 10 −1 S/cm at 120 °C, which are almost 2–3 times higher than that of Nafion 117 at the same measurement conditions. Consequently, these materials proved to be promising as proton exchange membranes.