Composite membrane formed from polymer blend including self-assembling block copolymers
AssigneeDow Global Technologies LLC
InventorsScott G. Gaynor, Daniel J. Murray, H. C. Silvis, Yasmin N. Srivastava, Junyan Yang
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Abstract
A method for making a composite membrane including the formation of a porous discriminating layer upon a surface of a porous support, including the step of a) forming a polymer blend comprising: i) a “blending” polymer and ii) a block copolymer comprising durable segments that form a co-continuous phase with the blending polymer and fugitive segments that form self-assembled assembled micro-domains within the co-continuous phase, and b) removing at least a portion of the fugitive segments to yield pores having an average size of ≦0.5 μm.
Claims6
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.
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:
The method of any of the preceding claims wherein the first and second polymers comprising at least 50 mole percent of common repeat units.
The method of any of the preceding claims wherein the first polymer comprises a homo or co-polymer of polyvinylidene fluoride.
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.
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.
Dependencies are inferred from the claim text.