Preparation And Marine Anticorrosion Properties Of Poly(3,4-ethylenedioxythiophene) Coatings

Conducting polymers with special structure, excellent physical and chemical properties as functional materials are now considered as a very important class of electroactive and photoactive materials, due to their rich structure, easy processing, and light proportion, which leads to extensive applications, such as, energy, electrochromic devices, information, sensors, novel conducting materials, etc. Since1985, DeBerry reported polyaniline film which was electrodeposited on stainless steel could passivate metal surface, many studies have focused on the anticorrosion application of polyaniline (PANi) and polypyrrole (PPy). It’s fast becoming a hot research topic in the field of metal corrosion protection. Conducting polymers were one of the main goals in the research and development of metal corrosion protection, because of their easily synthesis, environmental stability, observable anticorrosion, and environmental protection. As we known, among the large numbers of conducting polymers used in metal corrosion protection, polyaniline and polypyrrole have attracted great interest and processing technology mature. In contrast, polythiophene and its derivatives have received very little attention. Therefore, the research and application of polythiophene and its derivatives in metal corrosion protection are of great interest.Poly(3,4-ethylenedioxythiophene)(PEDOT) is well known and considered as the most remarkable conducting polymers, which is of particular interest due to its high electrical conductivity and environmental stability. PEDOT coatings prepared via electrodeposition and blend composite were used in metal corrosion experiments, and corrosion mechanisms of PEDOT coatings were discussed in details.(1) In acetonitrile and aqueous solutions, PEDOT films were electrochemically deposited on the surface of304stainless steel, and via the potentiodynamic polarization, open circuit potential and electrochemical impedance tests to assess the corrosion protection of PEDOT films for stainless steel in NaCl solution. It was found that PEDOT coatings could slow the pitting corrosion on stainless steel.(2) PEDOT/PSS-Epoxy composite coatings were prepared by blending PEDOT/PSS and epoxy resin, which were brushed on the marine steel and cured at room temperature. The corrosion tests of coatings showed that the addition of PEDOT/PSS could effectively strengthen the corrosion resistance of the conventional epoxy. However, the mechanical properties of coatings were influenced because of the introduction of PEDOT/PSS aqueous solution.(3) To improve the performances of coating, polyethylene glycol-1000(PEG-1000) was added into the PEDOT/PSS-Epoxy coating. Through stress-strain tests and electrochemical impedance spectroscopy, the mechanical properties and corrosion resistance of the coating were assessed. The addition of PEG reduced the differences of phase of two blends, and PEDOT was well dispersed in epoxy resin. The optimized performances of the modified coating, reduced the adverse effects from the introduction of water phase and improved the corrosion resistance of the composite coating.