Polymer networks of different cross-linking densities were prepared by copo
lymerisation of hydroxyethyl acrylate and ethylene glycol dimethacrylate. T
he average molecular weight between cross-links as well as the polymer chai
n mobility were characterised by means of dynamic-mechanical spectroscopy.
Equilibrium sorption iso-therms and the water uptake in immersion in liquid
water allowed the determination of the Flory-Huggins interaction parameter
between water molecules and polymer chain segments, which decreased with t
he water activity in the hydrogel and increased with the crosslinking densi
ty as a consequence of the hydrophobic character of the cross-linking agent
. Dynamic sorption and desorption experiments were used to determine the di
ffusion coefficient.