Determination of Polymer—Solvent Interaction Parameter from Swelling of Networks: The System Poly(2-hydroxyethyl Methacrylate)-Diethylene Glycol

Poly(2-hydroxyethyl methacrylate) gels are prepared by cross-linking with various amounts of ethylene glycol dimethacrylate in diethylene glycol solvent. The degree of swelling of the networks in diethylene glycol is measured in the range 0 < v₂< 0.35 as a function of cross-link density and solvent content during cross-linking. Results of swelling measurements are used to determine the polymer-solvent interaction parameter % of the system. An expression of the form x “ 0.49 - 0.25l>₂, where v₂is the polymer volume fraction, is estimated for the investigated system at 25 °C, which is in agreement with Janacek and Ferry's results. The analysis of experimental data provides information about the effective network chain length, which is found to differ appreciably from the one expected from stoichiometry.