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 films 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 reflectance Fourier transform infrared (ATR FT-IR) spectroscopy, the effects of pH, concentration of surface reacting species, and cross-linking conditions on the formation of multilayered structures are investigated. Quantitative ATR FT-IR analysis reveals that, when thin films are deposited by dipping, HP is immobilized to form covalent −CH2NH− linkages between PEI-NH2, and terminal HP-CHO groups. However, when spin-coating is utilized as an application method, HP takes a parallel orientation, and ionic complexes between PEI-NH3 +(OH-) and HP-SO3 -(H3O+) are formed. Quantitative analysis indicates that the surface concentration of individual layers is significantly lower for spin-coated layers.