Facile method for covalent-bonding coating of crosslinked silicone layer onto poly(ester-urethane) surface to improve tensile properties and hemocompatibility

Abstract In this paper, a facile method was provided to prepare covalent-bonding coating of crosslinked silicone (CLS) layer onto the poly(ester-urethane) (PEU) surface for improving its properties. The PEU containing well-ordered hard segments was prepared by the direct chain extension of poly(e-caprolactone) with diurethane diisocyanate (HBH), and the PEU films were acquired via solvent evaporation. The CLS layer was covalently coated onto the film surface by a three-step chemical treatment: the -NCO groups were first introduced onto the PEU film surface by chemical treatment of the film with hexamethylene diisocyanate; the free N CO groups were subsequently coupled with the N H2 groups of γ-aminopropyltriethoxysilane to fix the active alkoxysilane groups on the surface; finally, the alkoxysilane groups self-crosslinked to produce a CLS coating on the PEU surface (PEU-Si). FT-IR, XPS and SEM were used to characterize the modified surface. The studies on physicochemical properties of the films manifested that the PEU-Si film exhibited higher thermal stability, excellent tensile properties (broken elongation: 1389 %; ultimate strength: 41.6 MPa), and slower in vitro hydrolytic degradation (only 16.0 % weight loss after 18 months of degradation) than PEU film. The hemocompatibility evaluation of film surface was performed by protein adsorption and platelet adhesion measurements, and the results showed that the CLS-coated surface strongly inhibited protein adsorption (2.92 μg/cm2) and platelet adhesion (2,129 platelets/mm2). The PEU-Si exhibited excellent tensile properties, slow degradability, and superior surface hemocompatibility, indicating promise as a long-term implant.