DESIGNS OF ANION EXCHANGE MEMBRANES FROM POLY (2,6-DIMETHYL-1, 4-PHENYLENE OXIDE)

摘要

Ion exchange membranes have found many applications ever since they were invented in the last century. For examples, they can be used in electrodialysis to concentrate or dilute in aqueous or non-aqueous electrolyte systems, and in diffusion dialysis to recover acid or alkali from waste acid or alkali solutions [1-3]. For these applications, preparation of ion exchange membrane is the first step and is of great significance. Now different preparation methods are available from either monomers (polymerization) or enginerrring plastics (modifications). Amond these metthod, ion exchange membranes from the latter case is simple and cheap. Many commercial polyers are readyfor such use. Poly (2,6-dimethyl-1,4-phenylene oxide) (PPO), characterized by a high glass transition temperature (Tg=212℃) and good thermal stability under nonoxidizing conditions, is one of the most widely used engineering plastics. Due to its special structures with both methyl groups and phenyl groups, many modifications can be made with methyl or/and phenyl groups such as sulphonation, bromination, chloromethylation, chloroacetylation, etc., thus it is a good starting material for ion exchange membranes [4]. Therefore, in this chapter, the detail preparation route for series of anion exchange membranes will be described.