Simultaneous study of molecular and micelle diffusion in a technical microemulsion system by dynamic light scattering
| Autor: | Andreas P. Fröba, Michael H. Rausch, Cédric Giraudet, Matthias S. G. Knoll, Christian Joachim Hahn |
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| Rok vydání: | 2019 |
| Předmět: |
Molecular diffusion
Materials science Observable 02 engineering and technology 010402 general chemistry 021001 nanoscience & nanotechnology 01 natural sciences Micelle 0104 chemical sciences Surfaces Coatings and Films Electronic Optical and Magnetic Materials Condensed Matter::Soft Condensed Matter Biomaterials Colloid and Surface Chemistry Pulmonary surfactant Dynamic light scattering Chemical physics Scientific method Microemulsion Diffusion (business) 0210 nano-technology |
| Zdroj: | Journal of Colloid and Interface Science. 544:144-154 |
| ISSN: | 0021-9797 |
| Popis: | Hypothesis The application of dynamic light scattering (DLS) is well-established for measuring diffusion coefficients related to either molecular or translational micelle diffusion. The simultaneous determination of both transport properties should be feasible, but has not been reported in the literature yet. Experiments Different diffusion modes present in a microemulsion and selected subsystems consisting of a polyol mixture, a binary surfactant mixture, and carbon dioxide (CO2) were investigated systematically by DLS at temperatures of (314, 333, and 353) K and corresponding pressures of (10, 13, and 16) MPa. Findings Diffusion coefficients related to molecular and translational micelle diffusion could be measured simultaneously and increase with increasing temperature. From the translational diffusion coefficients, an increase in the hydrodynamic diameter of the micelles from their non-swollen to the CO2-swollen state being in agreement with literature data for the same and similar microemulsions was found. The effective diffusion coefficients related to the faster molecular diffusion process only observable in the presence of CO2 are not affected significantly by the surfactant. The time-dependent parts of the recorded intensity correlation functions related to molecular diffusion processes are heterodyne because the scattered light modulated by molecular concentration fluctuations is superimposed with light scattered by the micelles. |
| Databáze: | OpenAIRE |
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