Reactions of thrombresistant multilayered thin films on poly(vinyl chloride) (PVC) surfaces: A spectroscopic study

These studies focus on the formation of multilayered thrombresistant thin f ilms containing poly(ethylenimine) (PEI), dextran sulfate (DS), and heparin (HP), deposited on poly(vinyl chloride) surfaces. Dipping and spin-coating are employed to deposit multilayers, and using attenuated total reflectanc e Fourier transform infrared (ATR FT-IR) spectroscopy, the effects of pH, c oncentration of surface reacting species, and cross-linking conditions on t he formation of multilayered structures are investigated. Quantitative ATR FT-IR analysis reveals that, when thin films are deposited by dipping, HP i s immobilized to form covalent -CH2NH- linkages between PEI-NH2, and termin al HP-CHO groups. However, when spin-coating is utilized as an application method, HP takes a parallel orientation, and ionic complexes between PEI-NH 3+(OH-) and HP-SO3-(H3O+) are formed. Quantitative analysis indicates that the surface concentration of individual layers is significantly lower for s pin-coated layers.