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Degen P, Paulus M, Maas M, et al. In situ observation of gamma-Fe2O3 nanoparticle adsorption under different monolayers at the air/water interface. Langmuir. 2008;24(22):12958-62doi: 10.1021/la802394a.
Degen, P., Paulus, M., Maas, M., Kahner, R., Schmacke, S., Struth, B., Tolan, M., & Rehage, H. (2008). In situ observation of gamma-Fe2O3 nanoparticle adsorption under different monolayers at the air/water interface. Langmuir : the ACS journal of surfaces and colloids, 24(22), 12958-62. https://doi.org/10.1021/la802394a
Degen, Patrick, et al. "In situ observation of gamma-Fe2O3 nanoparticle adsorption under different monolayers at the air/water interface." Langmuir : the ACS journal of surfaces and colloids vol. 24,22 (2008): 12958-62. doi: https://doi.org/10.1021/la802394a
Degen P, Paulus M, Maas M, Kahner R, Schmacke S, Struth B, Tolan M, Rehage H. In situ observation of gamma-Fe2O3 nanoparticle adsorption under different monolayers at the air/water interface. Langmuir. 2008 Nov 18;24(22):12958-62. doi: 10.1021/la802394a. Epub 2008 Oct 14. PMID: 18850729.
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Langmuir. 2008 Nov 18;24(22):12958-62. doi: 10.1021/la802394a. Epub 2008 Oct 14.

In situ observation of gamma-Fe2O3 nanoparticle adsorption under different monolayers at the air/water interface.

Langmuir : the ACS journal of surfaces and colloids

Patrick Degen, Michael Paulus, Michael Maas, Rainer Kahner, Saskia Schmacke, Bernd Struth, Metin Tolan, Heinz Rehage

Affiliations

  1. Fakultat Chemie, Physikalische Chemie II, Technische Universitat Dortmund, 44227 Dortmund, Deutschland.

PMID: 18850729 DOI: 10.1021/la802394a

Abstract

We studied the adsorption of gamma-Fe 2O 3 nanoparticles from an aqueous solution under different charged Langmuir monolayers (stearic acid, stearyl alcohol, and stearyl amine). The aqueous subphase was composed of a colloidal suspension of gamma-Fe 2O 3 nanoparticles. The average hydrodynamic diameter of the nanoparticles measured by dynamic light scattering measurements was 16 nm. The observed zeta potential of +40 mV (at pH 4) results in a long-term stability of the colloidal dispersion. The behavior of the different monolayer/nanoparticle composites were studied with surface pressure/area (pi/ A) isotherms. The adsorption of the nanoparticles under the different monolayers induced an expansion of the monolayers. These phenomena depended on the charge of the monolayers. After the Langmuir/Blodgett transfer on glass substrates, the nanoparticle/monolayer composite films were studied by means of UV-vis spectroscopy. The spectra pointed to increasing adsorption of the nanoparticles with increasing electronegativity of the monolayers. On the basis of these results, we studied the in situ adsorption of nanoparticles under the different monolayers by X-ray reflectivity measurements. Electron density profiles of the liquid/gas interfaces were obtained from the X-ray reflectivity data. The results gave clear evidence for the presence of electrostatic interaction between the differently charged monolayers and the positively charged nanoparticles. While the adsorption process was favored by the negatively charged stearic acid monolayer, the positively charged layer of stearyl amine prevented the formation of ultrathin nanoparticle layers.

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