Preparation of bipolar membranes. II

The bipolar multilayer membrane was prepared by a new technique. The interf acial layer and cation layer were formed by only one step. The anion and ca tion layers were made from the same material from which chloromethylated po lysulfone was used as a basic material. The bipolar membranes were composed of a solvent-resistant anion layer with crosslinking matrix by the reactio n of chloromethylated polysulfone in DMF with diamine; an ultrathin interfa cial layer from chloromethylated polysulfone solution in DMF, containing ca tion-exchange resin and both quaternary and nonquaternary amine groups; and a cation layer from chloromethylated polysulfone dispersing cation resin p owder. The prepared bipolar membrane exhibits a lower voltage drop over 100 mA/cm(2) and stable performances at a long-term operation. (C) 2001 John W iley & Sons, Inc.