title: Permselectivity and conductivity of membranes based on sulfonated naphthalenic copolyimides.
abstract: A series of sulfonated diamines were synthesized which were further used to obtain relevant sulfonated naphthalenic copolyimides. Tough and ductile membranes were cast from solutions of the copolyimides in dimethylsulfoxide, which exhibit high ion-exchange capacity and high water uptake. The protonic conductivity of the membranes equilibrated with water lies in the range 1.0-8.6 S/m, at 25 degrees C, being of the same order of magnitude as that reported for perfluorinated acidic membranes. The values of the transport number of protons and sodium ions are close to the unit for very dilute electrolyte solutions, but they lie in the range 0.80-0.90 for moderate concentrations. The membranes exhibit rather high electroosmotic permeability. The similarity of the diffusion coefficients of protons and water in the membranes suggests that the Grottus mechanism governs the protonic conductive process in the acidic membranes equilibrated with water.
authors.affiliation: Department of Polymer Science and Engineering, Shanghai Jiao Tong University, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Guo
authors.forename: Fengxia
authors.initials: F
authors.lastname: Zhai
authors.forename: Jianhua
authors.initials: J
authors.lastname: Fang
authors.forename: Maria Fe
authors.initials: MF
authors.lastname: Laguna
authors.forename: Mar
authors.initials: M
authors.lastname: López-Gonzalez
authors.forename: Evaristo
authors.initials: E
authors.lastname: Riande