Modification of polyacrylonitrile membranes by incoherent IR radiation

Polyacrylonitrile (PAN) membranes with the rejection coefficients of bovine serum albumin (M w = 69000 Da) up to 97% have been developed. The effect of IR irradiation of PAN membranes at temperatures to 180°С has been studied for the first time. It has been found that the IR modification of the membranes at 120°С for 5 min makes PAN insoluble in a wide range of organic solvents. The test PAN membranes were obtained from PAN solutions in dimethyl sulfoxide (DMSO) with different polymer concentrations in casting solution. The morphology and filtration characteristics of the membranes are almost unaffected by the treatment. The permeability of the membranes to DMSO, dimethylformamide (DMF), dimethylacetamide (DMAA), and N-methyl-2-pyrrolidone (NMP) has been measured. It has been demonstrated that the IR-treated PAN membranes can be used for filtering the above solvents, although the initial polymer is soluble in these solvents. These membranes can also be used as supports of chemically resistant nanofiltration membranes for aprotic solvents.