Thermodynamic analysis of the surface of biomaterials

Graft copolymerization of N,N-dimethylacrylamide onto low density polyethylene and polytetrafluoroethylene films, and of acrylic acid onto polyvinylchloride film was carried out to obtain hydrogels. The critical surface tension (gamma(c)) of the graft copolymer surfaces determined by differential scanning calorimetry and the biological performance of grafted poly(N,N-dimethylacrylamide) hydrogels indicates that the graft copolymers obtained are biocompatible materials, Analysis of the platelet adhesion brings the observations into yet closer agreement with thermodynamic predictions based on free energy hypotheses, The arrangement of surface water molecules can explain the different adhesion capabilities of blood cells on this type of graft copolymer. In connection with this, a simple thermodynamic model is presented. (C) 1997 Elsevier Science B.V.