COMPOSITE MEMBRANE FORMED FROM POLYMER BLEND INCLUDING SELF-ASSEMBLING BLOCK COPOLYMERS

1 . A method of making a composite membrane comprising the steps of:

a) providing a porous support comprising a first polymer including a plurality of repeat units each comprising at least one structure unit; and

b) forming a porous discriminating layer upon a surface of the porous support, characterized by:

forming a polymer blend comprising:

i) a second polymer including a plurality of repeat units each comprising at least one structure unit, and wherein at least 50 mole percent of repeat units of the first and second polymers include a common structural unit, and

ii) a block copolymer comprising durable segments that form a co-continuous phase with the second polymer, and fugitive segments that form micro-domains within the co-continuous phase; and

removing at least a portion of the fugitive segments to yield pores having an average size of ≦5 μm.

2 . The method of the previous claim wherein the first and second polymers comprise at least 50 molar percent of repeat units including a structural unit selected from at least one of:

3 . The method of any of the preceding claims wherein the first and second polymers comprising at least 50 mole percent of common repeat units.

4 . The method of any of the preceding claims wherein the first polymer comprises a homo or co-polymer of polyvinylidene fluoride.

5 . The method of any of the preceding claims wherein the weight ratio of the second polymer to block copolymer is from 1:9 to 9:1.

6 . The method of any of the preceding claims wherein the molecular weight ratio of the durable segments to fugitive segments is from 1:6 to 2:1.