A Simple Technique to Measure the Friction Coefficient between Polymer Network of Hydrogel and Water

A simple apparatus to control water flow through a hydrogel at a fixed temperature was designed, in which the hydrogel was mechanically constrained in a glass microcapillary at gelation. An evaluation of the friction between the polymer network of polyacrylamide gels and the solvent water measured by this simple technique is presented here. The effects of the experimental conditions, the pressure applied to the solvent, the temperature and the gel size (the length and the cross-sectional area), on the friction coefficients were examined. The results agreed well with the model of the flux of water flow in a capillary based on the Hagen–Poiseuille equation.