鉄上でのポリアニリン電解重合膜の形態,耐食性に及ぼす電解条件の影響

摘要

近年，アニリン,ピロール，ビニル,フェノールのようなモノマーを用いて電解重合を行いそれらの高分子膜を金属基板に形成させる研究が行われている.この電解重合法では，高分子の合成および薄膜のコーティングを一段階で進行させることができ，高分子膜をFe上に均一に形成できれば，Feの耐食性を向上させることができる.一般に，電解重合膜の構造と特性は，単量体，支持電解質，電極材料の種類および電解条件などに依存して変化することが知られている.%Polyaniline films were formed on an Fe substrate using the oxidative electropolymerization technique at 288 K in aqueous solutions of pH 2 to 10 containing aniline and p-toluenesulfonic and oxalic acids as supporting electrolytes, and the effect of conditions of electrolysis on the morphology and corrosion resistance of the films was investigated. Although the polyaniline films were formed partially in solutions of pH 2 to 4， the formation of films completed and the surface became smooth in solutions of pH 7 to 10. Polyaniline films with a smooth surface and good corrosion resistance were obtained at 8 to 30 A·m~(-2), while the films obtained at current densities above 50 A·m~(-2) showed a non-uniform surface morphology and the insufficient corrosion resistance. Films obtained at anode potentials of 0.4 and 0.8 V vs. NHE were not formed completely, and the films formed at an anode potential of 2.0 V exhibited very rough surfaces. Films formed from the solution containing p-toluenesulfonic acid as a supporting electrolyte exfoliated from the Fe substrate following immersion in a 3 mass% NaCl solution for 3 h. Although the films obtained from the solution containing oxalic acid as a supporting electrolyte showed the good adhesion to the substrate, they possessed many defects and pores, and as a result, the improvement in the Fe's corrosion resistance was less. In the solution containing both p-toluenesulfonic and oxalic acids as supporting electrolytes, the Fe coated with polyaniline films showed the good improvements in both corrosion resistance and adhesion.