Process for making an ion exchange material

This invention relates to a process for making an ion exchange material, the process comprising: (A) forming an aqueous solution comprising a water-soluble polymer containing pendent carboxyl groups and a water-soluble polyol, the number of carboxyl groups provided by said polymer being in excess of the number of hydroxyl groups provided by said polyol; (B) forming a thin film or a composite with the solution from step (A), the composite comprising the solution from step (A) in contact with a support material; (C) drying the solution to form a dried polymer; (D) heating the dried polymer from step (C) under esterification conditions to produce a water-insoluble partially esterified crosslinked polymer; and (E) contacting said partially esterified crosslinked polymer from step (D) with alkali or alkaline earth metal ions to form said ion exchange material.