Growth kinetics and structure of a colloidal silica-based network: in situ RheoSAXS investigations

Silica gels have a multitude of applications ranging from cosmetics and food science to oil and gas recovery. For proper design and application, it is important to have a thorough understanding of the underlying mechanisms of gel formation under different circumstances. The growth and structure of colloidal silica gels has been investigated using RheoSAXS to study the effect of silica concentration, NaCl concentration, temperature and shear rate. Additionally, SAXS in combination with a strong magnetic field has been applied to investigate the effect of magnetic microparticles and magnetic field on the development of the gel structure. Results indicate that the strongest effect on the gel kinetics are achieved by altering the activator concentration, here in the form of NaCl, followed by silica concentration and temperature. Small structural effects were also observed, with larger cluster sizes being produced at lower silica concentration and at higher NaCl concentration. Applying shear caused major changes both in structure as well as the macroscopic behavior of the silica, preventing the gel from reaching an arrested state, instead forming a viscous liquid. Applying a magnetic field appears to suppress the formation of larger clusters. The same effect is observed for increasing magnetic microparticle concentrations.publishedVersio

CO2 Adsorption Enhanced by Tuning the Layer Charge in a Clay Mineral

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Intercalation of CO2 Selected by Type of Interlayer Cation in Dried Synthetic Hectorite

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Influence of CO2 on Nanoconfined Water in a Clay Mineral

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Dipolar ordering of clay particles in various carrier fluids

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Electric-stress-induced Slip Lines in Jammed Particle Monolayers

Drops fully covered by particles, so called Pickering emulsion drops, are used to stabilize emulsions and are ideal templates for producing particles and advanced capsules. Recent studies show how electrohydrodynamic circulation flows in drops can structure free particles on their surfaces. In this article, we study the structure of Pickering drops subjected to DC E-fields. Due to its effects, we observe plastic (irreversible) deformation of the two-dimensional granuar solid covering the droplet, including particle reorganisation similar to the “grain layer gliding” and “block gliding” typical of jammed granular matter

Electric field nematic alignment of fluorohectorite clay particles in oligomeric matrices

We study the behavior of fluorohectorite synthetic clay particles dispersed in paraffin wax. We report wide-angle x-ray scattering related to electric-field-induced alignment of the embedded clay particles. The development of anisotropic arrangement of the particles is measured during melting and crystallization of the composites. The degree of anisotropy is quantified by fitting azimuthal changes of the clay diffraction peak intensity to the Maier-Saupe function. This parametric function is then used to extract both the full width at half maximum (FWHM) and the amplitude of the anisotropic scattering and eventually to estimate a nematic order parameter for this system. Finally, the time evolution of the one-to-zero and zero-to-one water layer transition in paraffin embedded fluorohectorite clay galleries is presented, and we demonstrate that such particles can be used as “meso-detectors” for monitoring the local water content in bulk carrier matrices, such as paraffin wax