Osmotic pressure and phase boundary determination of multiphase systems by analytical ultracentrifugation

Page, Miles G.; Zemb, Thomas; Dubois, Monique; Cölfen, Helmut

Osmotic pressure and phase boundary determination of multiphase systems by analytical ultracentrifugation

Dateien

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Datum

2008

Autor:innen

Page, Miles G.

Zemb, Thomas

Dubois, Monique

Cölfen, Helmut

Publikationstyp

Zeitschriftenartikel

Publikationsstatus

Published

Erschienen in

ChemPhysChem. 2008, 9(6), pp. 882-890. ISSN 1439-4235. eISSN 1439-7641. Available under: doi: 10.1002/cphc.200700668

Zusammenfassung

We show that analytical ultracentrifugation can be applied to derive full equations of state of colloids in a single sedimentation equilibrium experiment, by determination of single-phase boundaries as well as of osmotic pressure versus concentration at fixed temperatures. A continuous dependence of the osmotic pressure, over orders of magnitude between at least ∼101 and 104 Pa, and a wide concentration range, are determined in agreement with standard theoretical considerations. Two model experimental colloidal systems are investigated: For a well-known synthetic clay system (laponite), it is shown that two regimes—counter-ion ideal gas and interacting double layers—can easily be identified in the equation of state, whereas metastable glass- or microphase-separated gel states previously encountered in osmotic stress measurements of laponite are circumvented. For the case of rigid, crystallized catanionic bilayers, single phase domains can be identified. Osmotic pressure results in this case disagree with results obtained using the classical osmotic stress technique, as a result of sample adhesion to the ultracentrifuge cell windows and uncertainty due to possible micromolar ion contamination.

Fachgebiet (DDC)

540 Chemie

Schlagwörter

clays, equation of state, osmotic pressure, phase transitions, sedimentation equilibrium

Zitieren

ISO 690

PAGE, Miles G., Thomas ZEMB, Monique DUBOIS, Helmut CÖLFEN, 2008. Osmotic pressure and phase boundary determination of multiphase systems by analytical ultracentrifugation. In: ChemPhysChem. 2008, 9(6), pp. 882-890. ISSN 1439-4235. eISSN 1439-7641. Available under: doi: 10.1002/cphc.200700668

BibTex

@article{Page2008-04-21Osmot-16652,
  year={2008},
  doi={10.1002/cphc.200700668},
  title={Osmotic pressure and phase boundary determination of multiphase systems by analytical ultracentrifugation},
  number={6},
  volume={9},
  issn={1439-4235},
  journal={ChemPhysChem},
  pages={882--890},
  author={Page, Miles G. and Zemb, Thomas and Dubois, Monique and Cölfen, Helmut}
}

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