The present invention provides a composite material comprising a support member that has a plurality of pores extending therethrough, a first polymer which durably coats the pores of the support member, the first polymer layer having both hydrophobic and hydrophilic properties, and a second polymer layer disposed on the surface of the first polymer layer, the second polymer being more hydrophilic than the first polymer layer. The present invention also provides a process for preparing the composite material, and its use as a separation medium.