Cholic acid is a versatile coating-forming dispersant for electrophoretic deposition of diamond, graphene, carbon dots and polytetrafluoroethylene

Abstract

Sodium cholate (ChANa) is used for the first time as an advanced charged dispersant and coating-forming molecular agent for electrophoretic deposition (EPD) of different advanced materials, such as diamonds, carbon dots, graphene and polytetrafluoroethylene (PTFE). The amphiphilic structure of ChANa facilitates its adsorption on the materials and allows their good dispersion. The coating formation mechanism is based on gel-forming properties as well as pH-dependent solubility and pH-dependent charge of ChANa. A conceptually novel strategy is proposed for the deposition of PTFE films and composites. PTFE films prepared by EPD show strong adhesion to stainless steel substrates. Potentiodynamic and impedance spectroscopy studies indicate that PTFE films provide corrosion protection of steel. The potentiodynamic studies of the coated stainless steel substrates show significant reduction of corrosion current, whereas impedance spectroscopy show increasing impedance. The film thickness is varied in the range of 1–30 μm by variation of deposition time in the range of 0.5–5 min and deposition voltage in the range of 7–50 V. Building on the strong dispersion power and electrochemical properties of ChANa we demonstrate the feasibility of composite film fabrication by a combined electrodeposition method, which involves electropolymerization of polypyrrole and EPD of diamonds. This investigation opens new and unexplored routes in the electrochemical deposition of advanced materials using ChANa as a co-dispersing and coating-forming agent.