title: Waterborne chitosan-epoxysilane hybrid pretreatments for corrosion protection of zinc.
abstract: Biopolymer-based systems are extensively studied as green alternatives for traditional polymer coatings, e.g., in corrosion protection. Chitosan-epoxysilane hybrid films are presented in this work as a chitosan-based protective system, which could, e.g., be applied in a pretreatment step. For the preparation of the chitosan-epoxysilane hybrid systems, a sol-gel procedure was applied. The function of the silane is to ensure adhesion to the substrate. On zinc substrates, homogeneous thin films with thickness of 50-70 nm were obtained after thermal curing. The hybrid-coated zinc substrates were characterized by infrared spectroscopy, ellipsometry, and x-ray photoelectron spectroscopy. As model corrosion experiments, linear polarization resistance was measured, and cathodic delamination of the weak polymer coating poly(vinylbutyral) (PVB) was studied using scanning Kelvin probe. Overall, chitosan-epoxysilane hybrid pretreated samples showed lower delamination rates than unmodified chitosan coatings and pure PVB. Electrochemical impedance spectroscopy confirmed a reduced ion permeability and water uptake by chitosan-epoxysilane films compared to that of a nonmodified chitosan coating. Even though the coatings are hydrophobic and contain water, they slow down cathodic delamination by limiting ion transport.
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Fernández-Solis
authors.affiliation: Department of Interface Chemistry and Surface Engineering, Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Str. 1, 40237 Düsseldorf, Germany and Department of Materials Science and Engineering, NTNU - Norwegian University of Science and Technology, 7491 Trondheim, Norway.
authors.forename: Andreas
authors.initials: A
authors.lastname: Erbe
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003343:Corrosion; D056951:Photoelectron Spectroscopy; D012821:Silanes / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D015032:Zinc / Q000378:metabolism*
chemical_list: D001704:Biopolymers; D003188:Composite Resins; D012821:Silanes; D048271:Chitosan; D015032:Zinc