High-Frequency Viscosity and Shear Modulus of Sterically Stabilized Colloid Particles as Probed by Torsional Resonance Oscillation

Weiß, A.; Ballauff, Matthias; Willenbacher, Norbert

doi:10.1006/jcis.1999.6281

Cited by 12 publications

(15 citation statements)

References 21 publications

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“…Willenbacher and colleagues have been the first to use this device for the study of colloidal suspensions. [79,80] They also showed that the data obtained at approximately 8 KHz refer to the highfrequency limits of G 0 and G 00 . The thickness D HF measured at this high frequency is obviously smaller than the respective low-frequency data if the network on the particles is swollen (low temperature).…”

Section: Flow Behaviormentioning

confidence: 91%

Nanoscopic Polymer Particles with a Well‐Defined Surface: Synthesis, Characterization, and Properties

Ballauff

2003

Macro Chemistry & Physics

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We review our recent work on polymeric latex particles having a well‐defined surface of grafted polymers. Two types of particles are discussed: i) particles with a thermosensitive shell, and ii) particles bearing a dense layer of linear polyelectrolyte chains on their surface (“spherical polyelectrolyte brush”). Both types of particles consist of a polystyrene core onto which either linear or crosslinked chains are grafted. The synthesis of these core–shell particles proceeds in a two‐step process which is reviewed in detail. In particular, we discuss the photo‐emulsion polymerization used for the synthesis of the spherical polyelectrolyte brushes. Most of the studies of these particles have been done in aqueous suspension. Here the equilibrium structure of the surface layer of the particles has been investigated by dynamic light scattering and by small‐angle X‐ray scattering. Results deduced from the flow behavior of the particles in dilute solution can directly be derived from static data. Very recent data refer to the interaction of the spherical polyelectrolyte brushes with solid interfaces. It is demonstrated that particles bearing positively charged polyelectrolyte chains interact strongly with negatively charged surfaces. The strong interaction that is directly evident from AFM studies can be used to generate 2D networks of the particles on the surface.

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Section: Flow Behaviormentioning

confidence: 91%

Nanoscopic Polymer Particles with a Well‐Defined Surface: Synthesis, Characterization, and Properties

Ballauff

2003

Macro Chemistry & Physics

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“…Open questions are the influence of shape anisotropy, the role of roughness and non-central interactions in the viscosity and rigidity of colloidal aggregates and gels (Pantina and Furst 2005;Wang et al 2019), or the importance of short-range interactions and hydrodynamics in concentrated colloidal gels or glasses. Alternatively, the elastic response in the high-frequency limit can be used to derive the average interparticle pair-potential (Zwanzig and Mountain 1965), which has been applied for instance to sterically (Zwanzig and Mountain 1965;Elliott and Russel 1998;Weiss et al 1999;Nommensen et al 2000;Duits et al 2001) or electrostatically stabilised dispersions (Bergenholtz et al 1998b;Fritz et al 2002a).…”

Section: Applicationsmentioning

confidence: 99%

Bulk rheometry at high frequencies: a review of experimental approaches

et al. 2019

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High-frequency rheology is a form of mechanical spectroscopy which provides access to fast dynamics in soft materials and hence can give valuable information about the local scale microstructure. It is particularly useful for systems where timetemperature superposition cannot be used, when there is a need to extend the frequency range beyond what is possible with conventional rotational devices. This review gives an overview of different approaches to high-frequency bulk rheometry, i.e. mechanical rheometers that can operate at acoustic (20 Hz-20 kHz) or ultrasound (> 20 kHz) frequencies. As with all rheometers, precise control and know-how of the kinematic conditions are of prime importance. The inherent effects of shear wave propagation that occur in oscillatory measurements will hence be addressed first, identifying the gap and surface loading limits. Different high-frequency techniques are then classified based on their mode of operation. They are reviewed critically, contrasting ease of operation with the dynamic frequency range obtained. A comparative overview of the different types of techniques in terms of their operating window aims to provide a practical guide for selecting the right approach for a given problem. The review ends with a more forward looking discussion of selected material classes for which the use of high-frequency rheometry has proven particularly valuable or holds promise for bringing physical insights.

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“…These high frequency, low‐shear viscosity data of suspensions of rigid and uniformly porous spherical particles are obtained from numerical simulations using a hydrodynamic multipole method and cover broad ranges of permeability parameter β (defined in Equation (27)) and volume fraction of particles. One set of data deals with high‐frequency limiting shear viscosity of concentrated suspensions of solid core‐hairy shell particles, obtained experimentally. Two sets of data deal with high‐frequency limiting shear viscosity of concentrated suspensions of hard spheres .…”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…Figure 8. Comparison between model predictions and high-frequency oscillatory shear viscosity data [52][53][54][55] for suspensions of three different types of particles: wholly porous particles with different permeabilities, solid core-hairy shell composite particles, and hard spheres. The maximum packing volume fraction w m is taken to be 0.85 in Models 3 and 4. particles (porous particles, solid core-hairy shell particles, and hard spheres).…”

Section: Comparison Of Model Predictions With Viscosity Datamentioning

confidence: 99%

Viscosity models for concentrated suspensions of solid core‐porous shell particles

Pal

2015

Can J Chem Eng

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New models are developed for the low-shear viscosity of concentrated suspensions of solid coreporous shell particles taking into consideration the effects of the thickness and permeability of shell surrounding the solid core of the core-shell particles. The relative viscosity of suspension depends on factors such as: relative thickness of the porous shell, size of the composite (solid core-porous shell) particles, permeability of the shell, and volume fraction of the core particles.For given relative thickness of porous layer and size of the composite particles, the relative viscosity of suspension decreases substantially with the i ncrease in the permeability of the porous layer at a fixed volume fraction of core particles. Upon shrinking of the solid core, the relative viscosity of suspension exhibits a large increase provided that the size of the composite particles, the permeability of the porous shell, and the volume fraction of core particles are all kept constant. The proposed models are evaluated using data available on low-shear viscosity of concentrated suspensions of three different types of particles: porous particles, solid core -hairy shell particles, and hard spheres.

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High-Frequency Viscosity and Shear Modulus of Sterically Stabilized Colloid Particles as Probed by Torsional Resonance Oscillation

Cited by 12 publications

References 21 publications

Nanoscopic Polymer Particles with a Well‐Defined Surface: Synthesis, Characterization, and Properties

Nanoscopic Polymer Particles with a Well‐Defined Surface: Synthesis, Characterization, and Properties

Bulk rheometry at high frequencies: a review of experimental approaches

Viscosity models for concentrated suspensions of solid core‐porous shell particles

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