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.

Disclosed is a membrane surface modification method. The method is applicable to a variety of hydrophobic membranes by doping selected inorganic particles. One act of the method involves the in-situ embedment of the inorganic particles onto the membrane surface by dispersing the particles in a non-solvent bath for polymer precipitation. Further membrane surface modification can be achieved by hydrothermally growing new inorganic phase on the embedded particles. The embedment of particles is for the subsequent phase growth.

Described in the present application are methods of producing silane-crosslinked polymer membranes at moderate temperatures using acid catalysts that, in certain embodiments, result in membranes with unexpectedly high permeabilities and selectivities. In certain embodiments, grafting and crosslinking of the silanes occur by immersing a preformed membrane in a solution comprising a silane and an acid catalyst. Alternatively, in certain embodiments, grafting of silanes to a polymer occurs in the presence of acid catalyst in solution and subsequent casting and drying produces crosslinked membranes. In certain embodiments, an acid catalyst is a weak acid catalyst. Also described in the present application are asymmetric crosslinked polymer membranes with porous layers. In certain embodiments, crosslinked cellulose acetate membranes have permeability up to an order of magnitude greater than the permeability of unmodified cellulose acetate membranes. The membranes have porous layers with a high porosity due to their processing in moderate conditions.

An asymmetric membrane having a substantially non-porous surface layer is made by a method including: dissolving a poly(phenylene ether) copolymer in a solvent mixture including a first solvent and a second solvent to provide a membrane-forming composition; and phase-inverting the membrane forming composition in a first non-solvent to form the membrane comprising a substantially non-porous surface layer. The first solvent is a water-miscible polar aprotic solvent, and the second solvent is a polar solvent having two to eight carbon atoms.

Disclosed is a hollow-fiber membrane blood purification device having an improved antioxidant performance, good water permeation performance and blood compatibility performance, and economic rationality. The present invention provides a hollow-fiber membrane blood purification device including hollow-fiber membranes filled in a vessel, in which the hollow-fiber membranes contain a hydrophobic polymer, a hydrophilic polymer and a fat-soluble vitamin, when a hollow-fiber membrane bundle is divided into five sections in a lengthwise direction and divided sections positioned in endmost portions are defined as body end portions, an amount of the fat-soluble vitamin present in at least one of the body end portions is the largest among amounts of the fat-soluble vitamin present respectively in all the divided sections, and an amount of the fat-soluble vitamin per m.sup.2 of a hollow-fiber membrane inner surface of the at least one body end portion is 20 mg/m.sup.2 or more and 300 mg/m.sup.2 or less.

The present invention deals with a method for obtaining membranes in the form of hollow fibers with application in the field of carbon dioxide removal from natural gas. The aforementioned membranes are obtained by means of heat treatment of polymeric membranes. In this method, polymeric membranes are obtained by a phase-inversion technique by immersion-precipitation and are subsequently subjected to a heat treatment, that is, that the membranes effectively become precursor membranes of the heat treatment. The heat treatment process involves the optimization of the heating rate, temperature, and stabilization time variables, aiming at the improvement of the transport properties of the polymeric membranes. After the heat treatment, it becomes possible to use the membranes in separation processes of gases which operate at pressures greater than 30 bar, with selectivity for carbon dioxide (CO.sub.2).

The further advancement of membrane separation processes requires the development of more selective membranes. In this study, membranes that take inspiration from biological systems and use multiple functionalities of unique chemical design to control solute transport through chemical factors in addition to steric factors are detailed. Specifically, copolymer materials tailor-made for the generation of nanofilters that possess a high density of well-defined pores lined by azido moieties allowed for the generation of chemically-patterned mosaic membranes in a rapid manner through the use of printing devices. By engineering the composition of the reactive ink solutions used for chemical functionalization, large areas of patterned membranes were generated in seconds rather than hours. Charge mosaic membranes were used as an example of this novel platform.

Disclosed is a membrane surface modification method. The method is applicable to a variety of hydrophobic membranes by doping selected inorganic particles. One act of the method involves the in-situ embedment of the inorganic particles onto the membrane surface by dispersing the particles in a non-solvent bath for polymer precipitation. Further membrane surface modification can be achieved by hydrothermally growing new inorganic phase on the embedded particles. The embedment of particles is for the subsequent phase growth.

Conventional porous membranes have a mesh structure having a relatively large pore diameter in order to improve the removability of a relatively large component such as a virus. When a contaminative liquid to be filtered is filtered, contaminants are easily accumulated in the porous membranes, clogging or the like occurs in the porous membranes, and contamination of the porous membranes easily occurs. Accordingly, an object is to provide a porous membrane having high contamination resistance and high-precision removability. To achieve the object, provided is a porous membrane including, in at least one surface, a surface portion spanning 10 ?m in thickness from the surface, being denser than an inner portion, and having a removal rate T of dextran having a weight-average molecular weight of 40,000 Da of 60 to 95%, in which a number of surface pores per unit area observed on the surface of the surface portion is 200 pores/?m.sup.2 to 2,000 pores/?m.sup.2.

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.