Institut für Funktionelle Grenzflächen (IFG)

Partitioning Behavior of Silica-Coated Nanoparticles in Aqueous Micellar Two-Phase Systems: Evidence for an Adsorption-Driven Mechanism from QCM-D and ATR-FTIR Measurements

  • Autor:

    Fischer, I. / Morhardt, C. / Heissler, S. / Franzreb, M. (2012)

  • Quelle:

    Langmuir 28 (2012), 45, 15789–15796

  • Datum: 2012
  • Fischer, I. / Morhardt, C. / Heissler, S. / Franzreb, M. (2012): „Partitioning Behavior of Silica-Coated Nanoparticles in Aqueous Micellar Two-Phase Systems: Evidence for an Adsorption-Driven Mechanism from QCM-D and ATR-FTIR Measurements“. In: Langmuir 28 (2012), 45, 15789–15796

Abstract

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Quartz crystal microbalance with dissipation (QCM-D), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and total organic carbon detection (TOC) are employed to examine the cause of the differences in the partitioning of silica-coated nanoparticles in an aqueous micellar two-phase system based on nonionic surfactant Eumulgin ES. The particles partition into the micelle-rich phase at pH 3 and into the micelle-poor phase at pH 7.

Our results clearly show that the nonionic surfactants are adsorbed to the silica surface at pH 3. Above the critical temperature, a stable surfactant bilayer forms on the silica surface. At pH 7, the surfactants do not adsorb to the particle surface; a surfactant-loaded particle is therefore drawn to the micelle-rich phase but otherwise repelled from it. These results suggest that the partitioning in aqueous micellar two-phase systems is mainly driven by hydrogen bonds formed between the surfactants and the component to be partitioned.