The effect of copolymer composition on surface free-energy of poly(2-hydroxyethyl methacrylate-crotonic acid) copolymers

Poly(2-hydroxyethyl methacrylate-crotonic acid) P(HEMA/CrA) copolymers with varying compositions were prepared from ternary mixtures of 2-hydroxyethyl methacrylate (HEMA)/crotonic acid (CrA)/water by using Co-60 gamma-rays. The wetting forces were determined according to the Wilhelmy Plate Technique. Di-iodomethane, ethylene glycol, and formamide were used as probe liquids. Lifshitz-van der Waals surface energy components, Lewis acid-base surface components, and total surface energies were calculated using van Oss et al. methodology. It was determined that Lifshitz-van der Waals component (gamma(S)(LW)) of the copolymers did not differ much from the copolymer composition. However, the electron-donor surface free energy components (gamma(S)(-)) of the copolymers were decreased considerably with the increase of the CrA content of the copolymers, the surfaces of these copolymers were still found to have a basic character.