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At present the problem of creating materials for medical application, which possess surface thromboresistant and antiseptic properties is of the great importance. The method of creating hydrogel films, containing anticoagulants, biologically active and antiseptic substances on the surface of well‐known polymers of medical purity allows to give their surface special functions and properties and to retain the good mechanical properties [1,2]. In the majority of cases, the methods which are used for the creation of such films have a limitations which impede their wide application as they do not allow to obtain surface layers, possessing different medico‐biological and physic‐chemical properties. The aim of our research was the electroformation of biocompatible, polyfunctional poly(vinyl alcohol) (PVA) films with immobilizied anticoagulant, enzyme and antibiotic on the surface of a composite material on the base of polysiloxane of medical purity [3,4].

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The hydrophilicity and hydrophobicity of surfaces was studied after their treatment with solutions of NaOH and polyethylene.The initial stage in design of medicinal composite materials consists in solving the problem associated with ensuring the adhesion compatibility of their constituent ingredients having different structures and surface properties, e.g., polymer3polymer, polymer3car-bon, polymer3metal [1,2].The aim of this study was to solve the problem of adhesion compatibility between the hydrophobic surface of the composite based on polysiloxane of medical purity (PDMS med ) and bulk-modified with graphite of S-1 brand [3] and the hydrophilic polyvinyl alcohol (PVC) film coating deposited on the surface of the composite in an electric field [4]. EXPERIMENTALIn order to enhance the biocompatibility of the composite [3], a hydrogel PVC coating was formed on its surface in an ac electric field with ultralow frequency (meander-type signal) [4,5]. A polyvinyl alcohol of medical purity [TU (Technical Specification) 605-05-26 375) was used for this purpose. As cross-linking agent served glutaric aldehyde (GA) and boric acid. Glycerol was introduced to ensure plasticity.The coating was formed in an electric field with the simultaneous immobilization of biologically active (trypsin, a proteolytic enzyme), medicinal (heparin, an anticoagulant; various antibiotics), and other substances, which made it possible to extend considerably the range of medical-biological properties of the starting material [4,5].To improve the adhesion of the hydrophilic polymer film coating to the hydrophobic surface of the composite, it was preliminarily treated with 5 and 10 M aqueous solutions of NaOH (special-purity grade) at 60 370oC for 2 h or with a 0.130.5% aqueous solution of polyethylene imine (PEI). Then the samples were washed with distilled water and dried at room temperature for 24 h. X-ray photoelectric spectra (XPS) of the composite were measured on an ESCA LAB-5 spectrophotometer with excitation by Al K = radiation (Mekhanobr Research-and-Production Association). The accuracy with which the peak positions were determined was + 0.1 eV. The accuracy of quantitative analysis was 10%.The adhesion of the hydrogel polymeric film coating to the surface of the composite was evaluated by the method of lattice cuts [6] [GOST (State Standard) 15 140 378].As revealed in a study of the adhesion, raising the concentration of the NaOH solution used to treat the surface of the composite to more than 5 M has no essential effect on the adhesion compatibility of the materials in question, even though this leads to a considerable increase in the number of reactive hydroxy groups on the surface and in their penetration into the material. In addition, use of a 10 M NaOH solution causes changes in the microprofile of the surface of the composite, i.e., makes more pronounced its roughness, which adversely affects the hemocompatibility of the material.