Highly swellable composite polyamide membrane

A method for making a composite polyamide membrane comprising a porous support and a thin film polyamide layer, wherein the method comprises applying a polar solution comprising a polyfunctional amine monomer and a non-polar solution comprising a polyfunctional acyl halide monomer to a surface of a porous support and interfacially polymerizing the monomers to form a thin film polyamide layer,

• wherein the method is characterized by the polar solution further comprising a tri-hydrocarbyl phosphate compound represented by Formula I:
• wherein R1, R2 and R3 are independently selected from hydrogen and hydrocarbyl groups comprising from 1 to 3 carbon atoms, with the proviso that no more than one of R1, R2 and R3 are hydrogen, and
• wherein the thin film polyamide layer is characterized by possessing an equilibrium water swelling factor of greater than 35% as measured by PFT-AFM.