Adsorption kinetics of organophosphonic acids on plasma-modified oxide-covered aluminum surfaces

  • chair:

    Giza, M. / Thissen, P. / Grundmeier, G. (2008)
  • place:

    Langmuir 2008, 24, 8688-8694
  • Date: 2008

  • Giza, M. / Thissen, P. / Grundmeier, G. (2008): „Adsorption kinetics of organophosphonic acids on plasma-modified oxide-covered aluminum surfaces“. In: Langmuir 2008, 24, 8688-8694

Abstract

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Tailoring of oxide chemistry on aluminum by means of low-pressure water and argon plasma surface modification was performed to influence the kinetics of the self-assembly process of octadecylphosphonic acid monolayers. The plasma-induced surface chemistry was studied by in situ FTIR reflection-absorption spectroscopy (IRRAS).

Ex situ IRRAS and X-ray photoelectron spectroscopy were applied for the analysis of the adsorbed self-assembled monolayers. The plasma-induced variation of the hydroxide to oxide ratio led to different adsorption kinetics of the phosphonic acid from dilute ethanol solutions as measured by means of a quartz crystal microbalance.

Water plasma treatment caused a significant increase in the density of surface hydroxyl groups in comparison to that of the argon-plasma-treated surface. The hydroxyl-rich surface led to significantly accelerated adsorption kinetics of the phosphonic acid with a time of monolayer formation of less than 1 min. On the contrary, decreasing the surface hydroxyl density slowed the adsorption kinetics.