Abstract: PDMS-b-PPO copolymers are synthesized by hydroxyl-amine condensation reaction,and applied in the separation of ethanol/water binary mixture by pervaporation.The reaction between aminopropyl-terminated PDMS and hydroxyl-terminated PPO are conducted for more than 10 h with the existence of dilute H₂SO₄ at 120 ℃.White powder-like block copolymers are obtained,and the structures are characterized by ¹H-NMR.Results show that the configurations of product are predicted to be AB and ABA types.Through solvent evaporation,the homogenous membranes are prepared,and results show that the membranes are ethanol perm-selective,compared with PDMS membranes,the separation performance and mechanical properties are improved.