| CPC B01D 71/36 (2013.01) [B01D 61/362 (2013.01); B01D 61/363 (2022.08); B01D 67/0002 (2013.01); B01D 67/0095 (2013.01); B01D 69/02 (2013.01); B01D 69/105 (2013.01); B01D 69/106 (2022.08); B01D 69/107 (2022.08); B01D 69/1216 (2022.08); B01D 71/261 (2022.08); B01D 2323/12 (2013.01); B01D 2323/219 (2022.08); B01D 2323/46 (2013.01); B01D 2323/50 (2013.01); B01D 2325/04 (2013.01); B01D 2325/06 (2013.01); B01D 2325/20 (2013.01); B01D 2325/38 (2013.01)] | 12 Claims |

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1. A method of fabricating a composite membrane comprising a perfluorinated polymer layer physisorbed on a surface of a polymer substrate layer, the method, comprising:
a) contacting a perfluorinated polymer solution with a surface of the polymer substrate layer in a drying chamber; and
b) drying the perfluorinated polymer solution in the drying chamber to form the perfluorinated polymer layer physisorbed on the surface of the polymer substrate layer;
wherein the perfluorinated polymer solution comprises a perfluorinated polymer and a C5-C18 perfluorinated solvent;
wherein the perfluorinated polymer solution is dried under an air flow of about 0.05 m/s to about 1.5 m/s, at a relative humidity of less than 20% and at ambient temperature in order to form the perfluorinated polymer layer, the layer having a surface morphology of 0% to 10% of its surface comprising micro-structures;
wherein the perfluorinated polymer layer has a thickness of about 5 nm to about 500 nm;
wherein the perfluorinated polymer layer comprises a perfluorinated polymer or a copolymer or blend thereof; and
wherein the polymer substrate layer comprises a non-perfluorinated polymer, or copolymer, or blend thereof.
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