AbstractDiffusion of some homologous series of solutes polyhydric alcohols, oligosaccharides, poly(ethylene oxide) polymers has been studied in cellulose gels (<20 w/w) and membranes (<60 w/w) and the same materials when acetylated. It was found that (1) The molecular weight dependence ofDapproximates that for the solutes in water alone; the activation energies are also identical to the value for diffusion in pure solvent. (2) The presence of the cellulose chains reduces the rate of diffusion to a degree which is approximately given by the Mackie—Meares equation. (3) Exclusion is pronounced, particularly with the acetylated membranes, and gives a high degree of molecular size discrimination by a sieving mechanism. The membranes have a very narrow range of “pore” sizes, whereas the gels have a contrastingly broad distrib
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