Synergistic effect of ionic liquid (IL) cation and anion inhibits negative difference effect on Mg in water- IL mixtures

D Kurchavov and U Rustambek and A Ottochian and A Seyeux and I Ciofini and P Marcus and V Lair and P Volovitch, CORROSION SCIENCE, 209, 110723 (2022).

DOI: 10.1016/j.corsci.2022.110723

Strong Negative Difference Effect (NDE) is present on Mg alloys in mPEGnMPyrClO4-H2O and BMPyrAcOH2O but not in mPEGnMPyrAcO-H2O mixtures. The role of mPEGnMPyr+ and its synergy with AcO- in waterionic liquids mixtures were characterized combining surface analysis by ToF-SIMS, surface and solution analysis by vibration spectroscopies and molecular dynamics simulations. The NDE was explained by the "free" water phase formation when Mg2+-ions expel water initially H-bonded with AcO-. Oxygen atoms of mPEGnMPyr+ can bond the released water, inhibiting the NDE. Water transport can be reduced by a condensed film, formed by mPEGnMPyr+ and AcO- coordinated with Mg2+ and Al3+.

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