ABSTRACT:The homogeneous grafting of methyl methacrylate onto cellulose was carried out in a dimethyl sulfoxide (DMSO}-paraformaldehyde solvent system. Three kinds of membranes were prepared: membranes of graft copolymers using ammonium persulfate (APS) as an initiator (APS membranes), membranes of those using azobisisobutyronitrile, and blended membranes of cellulose and poly(methyl methacrylate). The diffusive permeabilities of solutes through the membranes, the states of water in them, and their microphase separated structures depended on the kind of membrane. The permeabilities of solutes through three kinds of membranes were inferior to those through the membrane cast from the DMSO solution of cellulose. The APS membranes indicated specificity of permeation for vitamine 812, poly(ethylene glycol), and water. It was found that the fine microphase separated structure is essential for the improvement of the permeability through the membranes. The diffusive permeation of solutes through water-swollen membranes is considered to occur through water phases in them. 1 -? But the different states of water are present in membranes. 8 -19 Thus, characterization and quantification of water relating to the permeation of solutes seem significant for clarifying the mechanism of membrane permselectivity. acrylate (MA) as hydrophobic vinyl monomers decreased the water content of the membranes but improved the permeabilities of solutes through them. This was due to the change in the states of water in the membranes and increase in freezing water content.In membranes of different affinity for water, prepared from amphiphilic copolymers of various compositions, the states of water will differ from one another. In our previous studies, 20 -22 cellulose grafted with vinyl monomers in a homogeneous system was used as membrane materials. The permeabilities of solutes through the copolymer membranes and the states of water in them were investigated. The use of acrylonitrile (AN) and methyl In this study, homogeneous grafting onto cellulose was carried out with methyl methacrylate (MMA) which is thought more hydrophobic than AN and MA. The diffusive permeabilities of solutes through the MMA grafted cellulose membranes of various compositions are investigated in relation to the composition, microphase separated structures, and states of water in them.1341