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Producing polymer membrane e.g. ultrafiltration membrane, by preparing coating solution comprising two different volatile solvents, spreading casting solution into film, evaporating solvent near surface portion, and precipitating membrane
Producing polymer membrane e.g. ultrafiltration membrane, by preparing coating solution comprising two different volatile solvents, spreading casting solution into film, evaporating solvent near surface portion, and precipitating membrane
The method comprises preparing a coating solution comprising two different volatile solvents, in which amphiphilic block copolymer is dissolved with two different polymer blocks, where one of the polymer blocks is soluble in water and other polymer block is non-polar polymer block, spreading the casting solution into a film, evaporating the solvent near a surface portion for a period of time, and precipitating a membrane by immersing the film in a non-aqueous precipitation bath. The homopolymer and/or copolymer is dissolved in the solution. The method comprises preparing a coating solution comprising two different volatile solvents, in which amphiphilic block copolymer is dissolved with two different polymer blocks, where one of the polymer blocks is soluble in water and other polymer block is non-polar polymer block, spreading the casting solution into a film, evaporating the solvent near a surface portion for a period of time, and precipitating a membrane by immersing the film in a non-aqueous precipitation bath. The homopolymer and/or copolymer is dissolved in the solution. The polymer block of the amphiphilic block copolymer corresponds to a same length or differ from the polymer. The lengths of the polymer amphiphilic block copolymer are relative to each other so that a self-assembly of the polymers is performed in the solvent to form a cylindrical or spherical structure. A weight ratio between the polymers is 3:1-6:1. The block copolymer has a molecular weight of 200-300 kDa. The solvent is a non-solvent in the non-polar polymer block. The block copolymer is present in amount of 15-25 wt.%. The precipitation bath is cooled at a temperature of less than 4[deg] C. The casting solution is filled with a support material such as a non-woven material. The membrane is washed and/or dried in the precipitation bath. The membrane has an isopore separating-active layer having a pore diameter of less than 3.
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