THERMODYNAMIC ANALYSIS OF THE SURFACE OF BIOMATERIALS

Graft copolymerization of N,N-dimethylacrylamide onto low density poly ethylene and polytetrafluoroethylene films, and of acrylic acid onto p olyvinylchloride film was carried out to obtain hydrogels. The critica l surface tension (gamma(c)) of the graft copolymer surfaces determine d by differential scanning calorimetry and the biological performance of grafted poly(N,N-dimethylacrylamide) hydrogels indicates that the g raft copolymers obtained are biocompatible materials, Analysis of the platelet adhesion brings the observations into yet closer agreement wi th thermodynamic predictions based on free energy hypotheses, The arra ngement of surface water molecules can explain the different adhesion capabilities of blood cells on this type of graft copolymer. In connec tion with this, a simple thermodynamic model is presented. (C) 1997 El sevier Science B.V.