PROVISION OF AROMATIC POLYSULFONE POLYMER WITH HYDROPHILICITY

PURPOSE:To afford an aromatic polysulfone polymer with hydrophilicity without impairing the excellent physical properties inherent therein such as heat resistance, by reaction between said aromatic polysulfone polymer with its terminal carrying eliminative group and active hydroxyl group-contg. hydrophilic compound. CONSTITUTION:An aromatic polysulfone polymer is afforded with hydrophilicity by connecting a hydrophilic compound, through ether linkage, to the terminal of said polymer, by reaction between (A) the aromatic polysulfone polymer with its terminal carrying eliminative group [pref. constituted by recurring unit of formula I and terminal section of formula II (X is halogen)] and (B) the active hydroxyl group-contg. hydrophilic compound (pref. Said hydroxyl group being such as to enable alcoholate anion to be formed by reaction with an alkali, e.g. a water-soluble oligomer or polymer constituted by 1-30 recurring units such as gelatin or at least one hydroxyl group- carrying compound such as formaldehyde). EFFECT:Stable in the hydrophilicity for a long period. USE:Particularly, raw material for thin film to form separation membranes such as reverse osmosis membranes.