Solute diffusion in polymer networks. Part 3.—Hydroxyethylcellulose gels; solvent effects and fluorescence depolarisation measurements

Abstract

Measurements of translational diffusion coefficients of oligosaccharides have been made as a function of temperature in a dilute hydroxyethylcellulose gel swollen in water, dimethyl formamide (DMF) and dimethyl sulphoxide (DMSO). The diffusion coefficients in the gel phase are substantially lower than the values for free diffusion in the bulk solvents in all cases. The influences of solvent character, temperature and polymer concentration on this reduction are discussed.

Fluorescence depolarisation measurements were made over a corresponding temperature interval in the same gel system using fluorescein freely dispersed in the gel phase and also conjugated to the matrix polymer. The results are discussed in terms of the microscopic viscosities of the systems.