The present invention relates to a method for producing a porous membrane, the method being characterized in that a solvent system comprising 2-pyrrolidone and N-alkyl-2-pyrrolidone is used, wherein the content ratio of 2-pyrrolidone to N-alkyl-2-pyrrolidone in the solvent system is from 90%:10% to 10%:90%, based on mass %, and wherein N-alkyl-2-pyrrolidone is N-propyl-2-pyrrolidone and/or N-butyl-2-pyrrolidone. Furthermore, the present invention relates to a porous membrane obtainable by said method. Moreover, the present invention relates to the use of a specific solvent system for the production of a porous membrane.

The present disclosure relates to an alkylated graphene oxide membrane comprising a plurality of graphene oxide layers, each graphene oxide layer including at least one graphene oxide sheet covalently coupled to a chemical spacer, the chemical spacer being of Formula I:

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The present disclosure also relates to a filtration apparatus comprising an alkylated graphene oxide membrane disposed on a support substrate.

Provided is a porous composite membrane including graphene oxide sheets; nanoparticles bound to a surface of the graphene oxide sheets solely by electrostatic and/or Van der Waals interactions. The present invention also relates to a method of producing the porous composite membrane, a gas separation system including the porous composite membrane, and uses of the porous composite membrane in a process for separating H.sub.2 from a gas stream and a process for reducing H.sub.2O swelling in a graphene oxide-based membrane.

A composite polyamide reverse osmosis membrane comprising a polyamide layer; where the polyamide layer has a thickness in the range of 50-250 nm, and large open spaces (i.e., free volumes); where the open spaces are defined by a ratio of water flux, J.sub.w, (gfd) divided by the average surface roughness, Ra, (nm) of the polyamide layer; wherein the composite polyamide reverse osmosis membrane has the ratio of J.sub.w/Ra>0.35 gfd/nm when tested at 65 psi, using an aqueous solution containing 250 ppm of NaCl; and a microporous support with a thickness ranging from 100-150 μm. The present invention also relates to processes of fabricating the composite polyamide reverse osmosis membrane.

The disclosure provides a method for preparing a hollow fiber membrane by melt spinning-stretching and selective swelling, including: preparing a nascent hollow fiber by melt spinning in an inert gas protective atmosphere by using an amphiphilic block copolymer as a film forming material, and stretching the nascent hollow fiber in the cooling process, a stretch rate being controlled at 200-540 mm/min, and a stretch ratio being controlled at 150-600%; immersing the obtained hollow fiber in a swelling solvent, and treating the hollow fiber in a water bath at 65° C. for 1 h; and then transferring the hollow fiber into a long-chain alkane solvent, treating the hollow fiber at the same temperature for 1-12 h, and after the completion of the treatment, immediately taking out the hollow fiber and drying the hollow fiber to obtain the hollow fiber membrane with a bicontinuous porous structure. By combining the melt spinning-stretching and the selective swelling, the method of the disclosure can synchronously and continuously improve the permeability and selectivity of the hollow fiber membrane. The treatment in the long-chain alkane solvent can make the polar chain excessively enriched on the surface of the membrane migrate inward, thereby improving the performance of the hollow fiber membrane.

An asymmetric polyvinylidene chloride copolymer membrane is made by a method using a dope solution comprised of a polyvinylidene chloride copolymer and a solvent that solubilizes the polyvinylidene chloride copolymer that is shaped to form an initial shaped membrane. The initial shaped membrane is then quenched in a liquid comprised of a solvent that is miscible with the solvent that solubilizes the polyvinylidene chloride copolymer but is immiscible with the polyvinylidene chloride copolymer to form a wet asymmetric polyvinylidene chloride copolymer membrane. The solvents are removed from the wet membrane to form the asymmetric polyvinylidene chloride (PVDC) copolymer membrane. The membrane then may be further heated to form a carbon asymmetric membrane in which the porous support structure and separation layer of the PVDC membrane is maintained. The asymmetric carbon membrane may be useful to separate gases such as olefins from their corresponding paraffins, hydrogen from syngas or cracked gas, natural gas or refinery gas, oxygen/nitrogen, or carbon dioxide and methane.

The invention relates to a method for creating a porous film through aqueous phase separation, the method comprising: i) providing an aqueous solution comprising a responsive copolymer, and optionally a charged polymer, wherein at least one of the monomers in the responsive copolymer is a responsive monomer; ii) forming the aqueous solution into a thin layer and contacting the thin layer of aqueous solution with an aqueous coagulation solution in which the responsive copolymer is not soluble, or contacting the thin layer of aqueous solution with an aqueous coagulation solution in which a complex comprising the responsive copolymer and the charged polymer is not soluble; and iii) allowing solvent exchange between the aqueous solution and the aqueous coagulation solution to produce a porous film. The invention further relates to porous films or membranes thus obtained.

The present invention is directed to surface-treated membranes comprising: (a) a porous substrate; and (b) a coating layer applied to the substrate. The coating layer is formed from a surface treatment composition comprising: (i) a first component comprising an organic solvent; and (ii) a second component comprising a fluorine-containing polymer and a solvent containing at least one C—F bond. The present invention is further drawn to a method of preparing a surface-treated filtration membrane, comprising: (a) contacting a porous substrate with a first component of a surface treatment composition, wherein the first component comprises an organic solvent; (b) subsequently contacting the porous substrate with a second component of the surface treatment composition, wherein the second component comprises a fluorine-containing polymer and a solvent containing at least one C—F bond; and (c) subjecting the porous substrate to a temperature of 25 to 90° C. for 1 to 180 minutes.

The present invention relates to a membrane (M) comprising an amorphous polymer (P) comprising repeat units of the formulas (RU1), (RU2) and (RU3). Moreover, the present invention relates to a process for the preparation of said membrane (M) and a filtration process, wherein a liquid permeates said membrane (M).

Articles including poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate) or poly(2,2,3,3,4,4,4-heptafluorobutyl acrylate), fluoropolymers that do not form perfluorooctanoic acid (PFOA) when they degrade and that exhibit unexpectedly good oil repellency, are described. A method of making a fluoropolymer-containing article includes depositing a fluoropolymer-liquid mixture onto porous filtration medium by contacting the porous filtration medium with a mixture comprising a fluoropolymer and a liquid to form the treated porous filtration medium; and removing the liquid. The fluoropolymer includes poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate) or poly(2,2,3,3,4,4,4-heptafluorobutyl acrylate). Methods of using the article are further described.