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Charged Polystyrene Nanoparticles Near a SiO2/Water Interface
Maja S Hellsing1, Adrian R Rennie2, Michael Rodal3
1Bioscience and Materials , RISE Research Institutes of Sweden , Box 5607, SE-114 86 Stockholm , Sweden.
Langmuir : the ACS Journal of Surfaces and Colloids
|December 6, 2018
Summary
Quartz crystal microbalance with dissipation (QCM-D) monitoring reveals how polystyrene particle dispersions behave at interfaces. The study shows particle-surface separation, not adhesion, influences viscoelastic properties, offering new insights into complex liquid characterization.
Area of Science:
- Colloid and Surface Science
- Materials Science
- Physical Chemistry
Background:
- Quartz crystal microbalance with dissipation (QCM-D) is a key technique for studying liquid-solid interfaces and complex liquid viscoelasticity.
- Understanding interfacial behavior of colloidal dispersions is crucial for various applications.
Purpose of the Study:
- To investigate the interfacial structure and high-frequency viscoelastic properties of charge-stabilized polystyrene particles in water using QCM-D.
- To explore how ionic strength and particle concentration affect these properties.
Main Methods:
- Utilized Quartz Crystal Microbalance with Dissipation (QCM-D) monitoring.
- Analyzed adsorption processes at liquid-solid interfaces.
- Employed a viscoelastic Kelvin-Voigt model to interpret QCM-D data.
Main Results:
- Observed increases in frequency and dissipation upon replacing water with particle dispersions at low ionic strength.
- Viscosity increased from 1.0 to 1.3 mPa s with particle volume fraction (0.005-0.07), exceeding predictions for non-interacting dispersions.
- Polystyrene particles were found to be separated from the surface by a layer of dispersion medium, not adhered.
Conclusions:
- The QCM-D response is explained by a viscoelastic Kelvin-Voigt model, indicating a dispersion medium layer of 50-250 nm.
- This layer thickness decreased with increasing particle concentration and salt addition.
- Surface attachment is not necessary for anomalous QCM-D responses; a viscoelastic liquid layer can induce similar effects.
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