Methods of making blended, isoporous, asymmetric (graded) films (e.g. ultrafiltration membranes) comprising two or more chemically distinct block copolymers and blended, isoporous, asymmetric (graded) films (e.g. ultrafiltration membranes) comprising two or more chemically distinct block copolymers. The generation of blended membranes by mixing two chemically distinct block copolymers in the casting solution demonstrates a pathway to advanced asymmetric block copolymer derived films, which can be used as ultrafiltration membranes, in which different pore surface chemistries and associated functionalities can be integrated into a single membrane via standard membrane fabrication, i.e. without requiring laborious post-fabrication modification steps. The block copolymers may be diblock, triblock and/or multiblock mixes and some block copolymers in the mix may be functionally modified. Triblock copolymers comprising a reactive group (e.g., sulfhydryl group) terminated block and films comprising the triblock copolymers.