Authors: S Checchia V Sabatini H Farina M A Ortenzi
Publish Date: 2017/02/07
Volume: 74, Issue: 10, Pages: 3939-3954
Abstract
In functional polymers with tunable hydrophilic behaviour like sulfonated polyarylethersulfone SPES high ionic conductance can be obtained directly by increasing the concentration of sulfonic moieties along the macromolecular chain This however often comes to the cost of excessive water sorption which can lead to membrane rupture and consequent device failure To overcome this drawback and to reconcile high hydrophilicity with the high mechanical properties of aromatic polymers we propose the use of SPES copolymers with a low degree of branching A series of branched SPES was synthesized using homogeneous onepot copolymerization by replacing an amount up to 09 mol of the difunctional monomer 44′dihydroxydiphenyl with the trifunctional 135trihydroxybenzene THB The polymers were characterized by 1HNMR spectroscopy intrinsic viscosity water sorption measurements thermogravimetric analysis and differential scanning calorimetry Like linear SPES branched SPES is totally amorphous and soluble in polar aprotic solvents lending itself to easy fabrication of membranes and coatings Besides reducing the water sorption and inplane swelling of SPES membranes upon equilibration in liquid branching also improves the retention of water in swollen membranesThis work was supported by Fondazione Cariplo under the Project 20100588 “NonFluorinated polymeric membranes and platinumfree catalytic systems for Fuel Cells PEMFCs with low cost and high efficiency” The authors wish to thank Professor G Di Silvestro for stimulating discussion and scientific projects
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