Ultra-small-angle scattering studies of complex fluids

Bhatia, Surita R.

doi:10.1016/j.cocis.2004.10.001

Cited by 32 publications

(20 citation statements)

References 54 publications

(48 reference statements)

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“…A scattering behavior of (3 < α < 4) has been observed in the literature previously for colloidal attractive glasses . Interestingly, most USAXS data reported in the literature for montmorillonite clay dispersions show exponential laws with 1 < α < 3. , …”

Section: Resultsmentioning

confidence: 56%

Flocculated Laponite-PEG/PEO Dispersions with Multivalent Salt: A SAXS, Cryo-TEM, and Computer Simulation Study

Thuresson¹,

Segad

Plivelic

et al. 2017

J. Phys. Chem. C

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The aim of this study is to scrutinize the mechanism behind aggregation, i.e., tactoid formation of nanostructures with the shape of a platelet. For that purpose, the clay minerals Laponite and montmorillonite have been used as model systems. More specifically, we are interested in the role of: the platelet size, the electrostatic interactions, and adsorbing polymers. Our hypothesis is that the presence of PEG is crucial for tactoid formation if the system is constituted by small nanometric platelets. For this purpose, SAXS, USAXS, Cryo-TEM, and coarse-grained molecular dynamics simulations have been used to study how the formation and the morphology of the tactoids are affected by the platelet size. The simulations indicate that ion–ion correlations are not enough to induce large tactoids solely if the platelets are small and the absolute charge is too low, i.e., in the size and charge range of Laponite. When a polymer is introduced into the system, the tactoid size grows, and the results can be explained by weak attractive electrostatic correlation forces and polymer bridging. It is shown that when the salt concentration increases the long-ranged electrostatic repulsion is screened, and a free energy minimum appears at short distances due to the ion–ion correlation effects. When a strongly adsorbing polymer is introduced into the system, a second free energy minimum appears at a slightly larger separation. The latter dominates if the polymer is relatively long and/or the polymer concentration is high enough.

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Section: Resultsmentioning

confidence: 56%

Flocculated Laponite-PEG/PEO Dispersions with Multivalent Salt: A SAXS, Cryo-TEM, and Computer Simulation Study

Thuresson¹,

Segad

Plivelic

et al. 2017

J. Phys. Chem. C

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“…Recent advances in ultra small angle scattering techniques offer advantages and complementary information. 25 Rheology and mechanical testing may nicely distinguish between properties of chemically 21 vs physically cross-linked polymerclay materials. 17,18 Since shear can influence both the macroscopic texture and the orientation of the anisotropic particle on the nanometer length scale, it is helpful to combine the above mentioned techniques and correlate changes in the mechanical properties with changes in structure on different length scales.…”

Section: Introductionmentioning

confidence: 99%

Supramolecular structures in nanocomposite multilayered films

Stefanescu

Dundigalla

Ferreiro

et al. 2006

Phys. Chem. Chem. Phys.

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We investigate the multilayered structures of poly(ethylene)oxide/montmorillonite nanocomposite films made from solution. The shear orientation of a polymer-clay network in solution combined with simultaneous solvent evaporation leads to supramolecular multilayer formation in the film. The resulting films have highly ordered structures with sheet-like multilayers on the micrometer length scale. The polymer covered clay platelets were found to orient in interconnected blob-like chains and layers on the nanometer length scale. Inside the blobs, scattering experiments indicate the polymer covered and stacked clay platelets oriented in the plane of the film. The polymer is found to be partially crystalline although this is not visible by optical microscopy. Atomic force microscopy suggests that the excess polymer, which is not directly adsorbed to the clay, is wrapped around the stacked platelets building blobs and the polymer also interconnects the polymer-clay layers. Overall our results suggest the re-intercalation of clay platelets in films made from exfoliated polymer-clay solutions as well as the supramolecular order and hierarchical structuring on the nanometer, via micrometer to the centimeter length scale.

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“…At lower Q ranges, n was equal to 4; so at length scales smaller than 200 nm, the polyisobutylene and polyisoprene remained phase segregated . The presence of bicontinuous phase separation in PAA in neat aqueous solution under shear was likely due to the more periodic structure of the PAA resulting from the stacking of PAA chains, as opposed to chains floating free in the solution at rest. , This observation is supported by the viscosity vs shear rate curves for the electrode slurry, in which viscosity decreased as a function of increasing shear rate (discussed later). Each PAA had its own solvent sheath, so the separation of PAA chains by the solvent sheaths can be thought of as the beginning of phase separation.…”

Section: Resultsmentioning

confidence: 86%

Understanding Binder–Silicon Interactions during Slurry Processing

et al. 2020

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The conformation of poly(acrylic acid) (PAA) as a function of shear during slurry processing to construct silicon-based anodes is elucidated via rheology-coupled ultra-small-angle neutron scattering (rheo-USANS). Rheo-USANS shows that PAA with encapsulated silicon exists as discrete aggregates that do not interact with one another. As a result, a well-connected matrix of silicon and carbon black dispersed in PAA does not exist; thus, the electrode is inhomogeneous. Raman mapping and X-ray photoelectron spectroscopy were used to confirm the electrode heterogeneity and further understand the cycling properties. These results are correlated to silicon surface chemistry to provide a pathway to making better electrodes.

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Ultra-small-angle scattering studies of complex fluids

Cited by 32 publications

References 54 publications

Flocculated Laponite-PEG/PEO Dispersions with Multivalent Salt: A SAXS, Cryo-TEM, and Computer Simulation Study

Flocculated Laponite-PEG/PEO Dispersions with Multivalent Salt: A SAXS, Cryo-TEM, and Computer Simulation Study

Supramolecular structures in nanocomposite multilayered films

Understanding Binder–Silicon Interactions during Slurry Processing

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