Abstract:

Ethyl isocyanate polysulfone (PS-SA) was prepared by introducing the —NCO active group onto the main chain of bisphenol A polysulfones matrix by the Friedel-Crafts alkylation reaction. Naphthalene sulfonic acid modified polysulfone (PS-NS) was obtained by using 2-naphthol-6,8-disulfonic acid dipotassium as the nucleophilic reagent in one pot. The PS-NS proton exchange membranes(PEMs) were fabricated by solution casting. The relationship between temperature and the basic properties including water uptake, swelling ratio and proton conductivity were explored. PS-NS exhibits excellent dimensional stability at high water sorption because they can form phase separation structure by locating the hydrophilic group far away from the main chain of polysulfones. The water uptake of PS-NS-4 PEMs(the bonding amount of sulfonic groups is 1.42 mmol/g) is as high as 27.2% at 25 ℃ and 40.3% at 85 ℃, but the corresponding swelling ratio is only 25.2% and 57.2%. The properties are very close to that of Nafion115 membrane under the same condition.

Key words: polysulfone, ethyl isocyanate, naphthalene sulfonic acid type, micro-phase separation, dimensional stability