Abstract: A process for producing a semipermeable membrane having a high flux, excellent in solute rejection and useful for reverse osmosis, ultrafiltration and the like which comprises dipping a semipermeable membrane of acrylonitrile polymer containing 40-100% by mole of acrylonitrile in a solution of an amine and/or an alkali, or casting a solution of said polymer containing an amine and/or an alkali to prepare a semipermeable membrane, and optionally, treating the semipermeable membrane thus obtained with plasma.

Abstract: A process for producing a semipermeable membrane having a high flux, excellent in solute rejection and useful for reverse osmosis, ultrafiltration and the like which comprises dipping a semipermeable membrane of acrylonitrile polymer containing 40-100% by mole of acrylonitrile in a solution of an amine and/or an alkali, or casting a solution of said polymer containing an amine and/or an alkali to prepare a semipermeable membrane, and optionally, treating the semipermeable membrane thus obtained with plasma.

Abstract: Ultrathin membranes for separating substances are obtained by exposing shaped articles comprising a water-soluble polymer or a mixture of a water-soluble polymer and water-insoluble polymer to a plasma of a gas selected from helium, argon, nitrogen, hydrogen, oxygen, carbon monoxide, carbon dioxide, ammonia, a hydrocarbon having 1 to 10 carbon atoms, an epoxide having 2 to 10 carbon atoms, or an alkylamine, or a mixture of these substances to crosslink the surface layer, and then washing the exposed articles with water to remove the unreacted portions. The membrane exhibits outstanding performance characteristics when used in the processes for separating or concentrating substances, such as reverse osmosis, ultrafiltration, and the like.

Abstract: A method for the preparation of a semipermeable membrane which comprises exposing porous shaped articles of polyacrylonitrile or copolymers thereof containing acrylonitrile in an amount of more than 40% by mole to a plasma.The resulting semipermeable membrane is very useful for separating substances by reverse osmosis or ultrafiltration.

Abstract: A process for improving the performances of semipermeable membranes which comprise an acrylonitrile polymer containing 40 to 100% by mole of acrylonitrile and have a bubble point of more than 0.1 kg/cm.sup.2, by dipping said membranes in an aqueous solution containing inorganic salts and/or protic acids.

Abstract: A method for the preparation of semipermeable membranes which comprises sulfonating porous membranes of acrylonitrile polymers containing acrylonitrile in an amount of 40% to 100% by mole.The resulting semipermeable membrane is very useful for separating substances by reverse osmosis or ultrafiltration.

Abstract: A method for the preparation of semipermeable membrane which comprises exposing porous shaped articles of polysulfone to a plasma.The resulting semipermeable membrane is very useful for separating substances by reverse osmosis or ultrafiltration.

Abstract: A method for the preparation of a semipermeable membrane which comprises exposing porous shaped articles of polyacrylonitrile or copolymers thereof containing acrylonitrile in an amount of more than 40% by mole to a plasma.The resulting semipermeable membrane is very useful for separating substances by reverse osmosis or ultrafiltration.

Abstract: A method for the preparation of semipermeable membranes is disclosed which comprises exposing porous shaped articles of polyacrylonitrile or copolymers containing acrylonitrile in an amount of more than 40% by mole to a plasma consisting essentially of a gaseous organic compound or the mixture of said gaseous organic compound and an inert gas at room temperature under a pressure of 0.01 to 10 Torr.

Abstract: A novel phosphorylated cellulose ester membrane containing 0.1 to 10% of phosphorus and having a selective permeability. This permselective phosphorylated cellulose ester membrane consists essentially of a phosphorylated cellulose ester obtained by reacting a phosphorylating reagent such as phosphorus oxychloride with a lower aliphatic acid ester of cellulose, which has a reactive hydroxyl group, in an organic solvent, and then hydrolyzing the resulting ester. The membrane can be used widely in separating materials by processes such as reverse osmosis, ultrafiltration, dialysis, electrodialysis, and the like.

Abstract: A semipermeable membrane is obtained by casting a cast solution comprising a mixture of a water-insoluble high polymer and a water-soluble high polymer, a mixture of a water-insoluble high polymer and a water-soluble surfactant or a mixture of a water-insoluble high polymer, a water-soluble high polymer and a water-soluble surfactant to form a shaped article, exposing the thus formed shaped article to a plasma to crosslink the surface thereof, and then washing the exposed article with water to remove uncrosslinked water-soluble high polymer or water-soluble surfactant. The membrane can be used for such substance separation methods as reverse osmosis, ultrafiltration and the like.

Abstract: Ultrathin membranes for separating substances are obtained by exposing shaped articles comprising a water-soluble polymer or a mixture of a water-soluble polymer and water-insoluble polymer to a plasma of a gas selected from helium, argon, nitrogen, hydrogen, oxygen, carbon monoxide, carbon dioxide, ammonia, a hydrocarbon having 1 to 10 carbon atoms, an epoxide having 2 to 10 carbon atoms, or an alkylamine, or a mixture of these substances to crosslink the surface layer, and then washing the exposed articles with water to remove the unreacted portions. The membrane exhibits outstanding performance characteristics when used in the processes for separating or concentrating substances, such as reverse osmosis, ultrafiltration, and the like.

Abstract: A novel phosphorylated cellulose ester membrane containing 0.1 to 10 % of phosphorus and having a selective permeability. This permselective phosphorylated cellulose ester membrane consists essentially of a phosphorylated cellulose ester obtained by reacting a phosphorylating reagent such as phosphorus oxychloride with a lower aliphatic acid ester of cellulose, which has a reactive hydroxyl group, in an organic solvent, and then hydrolyzing the resulting ester. The membrane can be used widely in separating materials by processes such as reverse osmosis, ultrafiltration, dialysis, electrodialysis, and the like.