ABSTRACT:The homogeneous graft copolymerization of acrylonitrile onto cellulose was carried out in a dimethyl sulfoxide (DMSO)-paraformaldehyde solvent system. Three kinds of membranes were prepared: higher grafting efficiency membranes (H-GE membrane), lower grafting efficiency membranes (L-GE membrane), and blended membranes. The diffusive permeability of solutes through the water-swollen membranes was investigated. The permeability and microphase separated structure depended remarkably on the kind of membrane. Permeability through the H-GE membranes increased with increasing polyacrylonitrile content and leveled off, but that through the L-GE and blended membranes decreased. Permeability through the H-GE membranes was superior to that through the cellulose membrane cast from the DMSO solution of cellulose. However, the good permeability through the H-GE membranes could not be explained by the difference in water content of membranes.KEY The commercial regenerated cellulose membrane, Cuprophan, produced by the cuprammonium process has been widely used as a hemodialysis membrane owing to its good solute permeability and mechanical strength. However, it is also recognized that the diffusive permeability of solutes of molecular weight ranging from hundreds to thousands is not so good. mechanical strength of the membranes. To produce membranes of good permeability and mechanical strength, many studies have been carried out on amphiphilic copolymer membranes having the proper composition of hydrophilic and hydrophobic regions which function to control solute permeation and support the membrane, respectively. 4 -10