Providing sustainable supplies of water and energy is a critical global challenge. Polymer membranes dominate desalination and could be crucial to power generation applications, which include reverse osmosis (RO), nanofiltration (NF), forward osmosis (FO), pressure-retarded osmosis (PRO), electrodialysis (ED), membrane capacitive deionization (CDI), and reverse electrodialysis (RED). Improved membranes with tailored water and salt transport properties are required to extend and optimize these technologies. Water and salt transport structure/property relationships provide the fundamental framework for optimizing polymer materials for membrane applications. The water and salt transport and free volume properties of a series of sulfonated styrenic pentablock copolymers were characterized. The polymers' water uptake and water permeability increase with degree of sulfonation, and the block molecular weights could be used to tune water uptake, permeability, and selectivity properties. The presence of fixed charge groups, i.e., sulfonate groups, on the polymer backbone influence the material's salt transport properties. Specifically, the salt permeability increases strongly with increasing salt concentration, and this increase is a result of increases in both salt sorption and diffusivity with salt concentration. The data for the sulfonated polymers, including a sulfonated polysulfone random copolymer, are compared to those for an uncharged polymer to determine the influence of polymer charge on salt transport properties. The sulfonated styrenic pentablock copolymer permeability data are compared to literature data using the water permeability and water/salt selectivity tradeoff relationship. Fundamental transport property comparisons can be made using this relationship. The effect of osmotic de-swelling on the polymers and the transport properties of composite membranes made from sulfonated styrenic pentablock copolymers are also discussed. The sulfonated styrenic pentablock copolymers were exposed to multi-valent ions to determine their effect on the polymer's salt transport properties. Magnesium chloride permeability depends less on upstream salt concentration than sodium chloride permeability, presumably due to stronger association between the sulfonate groups and magnesium compared to sodium ions. Triethylaluminum was used to neutralize the polymer's sulfonic acid functionality and presumably cross-link the polymer. The mechanical, transport, and free volume properties of these aluminum neutralized polymers were studied. / text

The proton exchange membrane fuel cells should have three major advantages: 1. micro-phase separation, 2. mechanical properties and 3. thermal stability. According to the recent literature and the material of core benzene ring poly (arylene ether)s studied by our group, this paper synthesize a series of the locally and densely sulfonated polymer. We use core benzene ring as the diol monomer and the containing CF3 groups as the fluorine monomer to synthesis poly (arylene ether)s via nucleophilic displacement reactions, and then use the different concentrations synthesized sulfonated polymer by sulfonic acid reaction. According to NMR¡¦s result we confirmed that the structure of synthetic materials is correct. By using GPC we get that the KP1, KP2, and KP3¡¦s molecular weight about 20000 (g/mol) ; The thermal stability up to 530OC for 5% loss in TGA under nithtrogen, to prove thisseries of polymer excellent thermal stability. After sulfonation, SKP1, SKP2 and SKP3¡¦s decomposition temperature decreased about 200OC ~ 250OC ranging with increasing degree of sulfonation. By DSC analysis, K1, K2 and K3 monomer's Tg followed up with the increase of the benzene ring number, however, the polymer does not have any apparent peak. About the Proton conductive, SKP2C IEC 2.23mequiv / g, water uptake 94%, the highest proton conductivity can be as high as 68.2 mS / cm, has been similar to Nafion 117 of 70 mS / cm.