A dual-layer membrane and a method for preparing thereof. By adding a modifying monomer containing an active group and a characteristic group to a dope solution or spinning solution during the preparation of the dual-layer membrane, the grafting reaction occurs between the active group of the monomer and the polymer in the dope solution or spinning solution, and the intermolecular interaction with other polymers is enhanced by the characteristic group of the monomer, to improve the miscibility between the polymers. The method is suitable for preparing both a dual-layer flat sheet membrane and a dual-layer hollow fiber membrane, and can realize the preparation of a dual-layer membrane with an interpenetrated structure at the interface under mild preparation conditions.

The present disclosure provides a flat-sheet polyamide membrane comprising a first major surface and a second major surface and a separation layer and a porous substructure in the cross section of the membrane between the first major and the second major surface, wherein the average pore size diameter in the separation layer is smaller than the average pore size diameters on the first and second major surfaces, wherein the average pore size diameter on the first major surface is larger than the average pore size diameter on the second major surface, wherein the separation layer is closer to the second major surface than to the first major surface. The present disclosure further provides a method for producing such membranes and a use of the membranes for nanofiltration or ultrafiltration purposes.

A method for producing a porous hollow fiber membrane for humidification, the method comprising dry-wet spinning a spinning dope comprising a water-soluble organic solvent solution composed of polyphenylsulfone resin and hydrophilic polyvinylpyrrolidone using water as a core liquid; then performing a crosslinking treatment at 120 to 220° C. for 1 to 20 hours; and then dipping the resultant in an acidic solution with a concentration of 5 to 500 ppm. The obtained porous hollow fiber membrane has improved hydrophilicity without impairing the wettability of the porous hollow fiber membrane. Since, humidification performance of the porous hollow fiber membrane alone can be improved, it is effective as a humidifying membrane for fuel cells.

The present invention provides a method for the preparation of an asymmetric membranes. More particularly, the new method relates to the use of a crosslinker contacted via vapour or liquid phase with the surface layer of a cast polymer film, followed by the immersion of said film in a coagulation bath. The formation of a crosslinked skin layer and the solidification of the membrane bulk can thus be decoupled in time.

Embodiments of the present invention relate to a nanofiltration composite membrane for use to purify water, the methods for preparing said nanofiltration composite membranes and to the nanofiltration composite membranes prepared accordingly.

A method is disclosed for forming a microporous membrane that incorporates an additive having low water solubility at the membrane's active surface from a precipitation fluid. The incorporated additive at the membrane's active surface can improve one or more of the membrane's hydrophilicity, wettability, anti-fouling behavior, blood compatibility, and stability over long periods of use or repetitive use. The microporous membrane with this modified active surface can be a hollow fiber, flat sheet, or other self-supporting shape. The microporous membranes can be used for membrane filtering or a solute and/or solvent exchange process, which involve contacting aqueous-based fluid or blood with the microporous membrane, such processes for dialysis, blood oxygenation, or blood separation filtering, or other processes.

A perfluoropolymer hollow fiber composite membrane preparation method includes the steps of (A) preparing a supporting layer of the perfluoropolymer hollow fiber composite membrane, (B) preparing a membrane casting solution, which includes obtaining a mixed solution by mixing a perfluoropolymer water dispersion emulsion, a spinning carrier and solvent, and defoaming the mixed solution at vacuum and a constant temperature, (C) preparing a nascent hollow fiber composite membrane, which includes compositing by uniformly coating the membrane casting solution on an outer surface of the supporting layer through an annular spinneret using chemical fiber concentric circle composite spinning technology, putting the supporting layer after compositing into a coagulant, solidifying and forming, and (D) drying after putting the nascent hollow fiber composite membrane to a hot air box, cleaning, sintering, and performing heat preservation. The prepared membrane has a thin wall, thermal and chemical resistance and good mechanical performance.

Fluorinated polyazoles, porous membranes made therefrom, methods of making the porous membrane, and methods of using the porous membrane for purifying water, are described. For example, the present disclosure describes fluorinated polyoxadiazoles and polytriazoles that are capable of fabricating flat sheet, hollow fiber, and electrospun porous membranes are described.

The present disclosure relates to a microporous hollow fiber filter membrane having a large inner diameter and a thin wall. The fiber can be used for sterile filtration of liquids or removal of particles from liquids. The disclosure further relates to a method for producing the membrane and a filter device comprising the membrane.

A porous membrane comprising a membrane-forming polymer (A) and a polymer (B) containing a methyl methacrylate unit and a hydroxyl group-containing (meth)acrylate (b1) unit. A flux of pure water to permeate the porous membrane is preferably 10 (m.sup.3/m.sup.2/MPa/h) or more and less than 200 (m.sup.3/m.sup.2/MPa/h). The contact angle of the bulk of the membrane-forming polymer (A) is preferably 60° or more. The membrane-forming polymer (A) is preferably a fluorine-containing polymer. The polymer (B) is preferably a random copolymer.