Dialysis membrane and method for its production

Abstract

A method for producing a dialysis membrane in hollow-fiber membrane or flat membrane geometry includes: a) making a casting or spinning solution for production of a base membrane for the dialysis membrane out of at least one polysulfone and at least one pore-forming hydrophilic additive in at least one organic solvent, b) bringing the casting or spinning solution into contact with a precipitating agent to form the base membrane, and c) rinsing out the at least one organic solvent after precipitation of the casting or spinning solution in flat or hollow-fiber form.

1 . A method for producing a dialysis membrane in hollow-fiber membrane or flat membrane geometry, the method comprising the steps of:
 a) making a casting or spinning solution for production of a base membrane for the dialysis membrane out of: i.) at least one polysulfone, which is selected from the group consisting of: a polysulfone, a sulfonated polysulfone, a polyethersulfone, a sulfonated polyethersulfone, a polyphenylsulfone, a sulfonated polyphenylsulfone, and mixtures thereof; and ii.) at least one pore-forming hydrophilic additive in at least one organic solvent, selected from the group consisting of: N,N-dimethylacetamide and N-Methyl-2-pyrrolidone;   b) bringing the casting or spinning solution into contact with a precipitating agent to form the base membrane; and   c) rinsing out the at least one organic solvent after precipitation of the casting or spinning solution in flat or hollow-fiber form,   wherein:   the base membrane produced in step b) is subjected to a surface modification to create a functional surface on the base membrane by carrying out at least one layer-by-layer deposition on a surface of the base membrane so as to preserve the dialysis membrane,   at least one polymeric polycationic bonding agent is applied as a first layer on the surface of the base membrane and at least one polymeric polyanion is applied on the polycationic layer as a second layer,   the at least one polymeric polycationic bonding agent is selected from the group consisting of: polyethylenimine chitosan, polylysine, polyarginine, polyornithine, and mixtures thereof,   a carboxylated polysaccharide or a sulfated polysaccharide is used as the at least one polymeric polyanion, and which is selected from the group consisting of: a dextran sulfate with a molecular mass (M w ) of 15 kDa to 1 MDa, a sulfated chitosan with a molecular mass (M w ) of 30 kDa to 750 kDa, a cellulose sulfate with a molecular mass (M w ) between 20 kDa and 1 MDa, and mixtures thereof; and   the pore-forming hydrophilic additive is selected from the group consisting of: polyvinylpyrrolidone [PVP], a short-chain glycol with 2 to 10 C atoms, triethylene glycol, propylene glycol, polyethylene glycol, polyethylene oxide, and mixtures thereof.   
     
     
         2 . The method according to  claim 1 , wherein net charge of the surface of the base membrane can be adjusted by amounts of sulfonated polymer or polyelectrolyte applied. 
     
     
         3 . The method according to  claim 1 , wherein the pore-forming hydrophilic additive is at least one of:
 polyethylene glycol or polyethylene oxide exhibiting molecular mass of 600 Da to 500 kDa (M w ); and   PVP exhibiting a molecular mass (M w ) of lkDa to 2.2 MDa.   
     
     
         4 . The method according to  claim 1 , wherein the at least one polymeric polycationic bonding agent is a polyethylenimine with a molecular mass (M w ) of 1 kDa to 2 MDa. 
     
     
         5 . The method according to  claim 1 , wherein the carboxylated polysaccharide or sulfated polysaccharide comprises at least one of a dextran sulfate with a molecular mass (M w ) of approximately 500 kDa or a sulfonated chitosan with a molecular mass (M w ) of 30 kDa to 750 kDa. 
     
     
         6 . The method according to  claim 1 , wherein the at least one polymeric polyanion is cellulose sulfate having a molecular mass (M w ) of approximately 100 kDa. 
     
     
         7 . A dialysis membrane produced by the method according to  claim 1 .