Rod-plate interactions in sepiolite-LAPONITE® gels: microstructure, surface chemistry and rheology.

Pure and composite clay gels of sepiolite and LAPONITE® at 4 wt% solids were characterised microstructurally and rheologically. They all displayed time-dependent behaviour, i.e.

Microstructure of Sodium Montmorillonite Gels with Long Aging Time Scale.

Purified sodium montmorillonite (SWy-2) gels of a few percent solids displayed pronounced time-dependent rheological or aging behavior with a long time scale. The aging behavior was characterized by an increasing yield stress with rest time. This increase continued even after a week of rest.

Surface chemistry, rheology and microstructure of purified natural and synthetic hectorite suspensions.

Natural (N-) and synthetic (S-) hectorite suspensions were found to display significant time-dependent rheology or ageing behaviour and shear thinning flow behaviour. The ageing behaviour was characterised by an increasing yield stress with rest time. The yield stress continued to increase even after a week of rest, a reflection of a long process.

The role of hydroxyethyl groups in the construction of wormlike micelles in the system of quaternary ammonium surfactant and sodium salicylate.

To understand the role of electrostatic interactions and hydrogen bonds in the formation of wormlike micelles with the aid of sodium salicylate, two quaternary ammonium surfactants with the headgroup decorated by one hydroxyethyl group N-cetyl-N-(2-hydroxyethyl)dimethylammonium bromide and two hydroxyethyl groups N-cetyl-N,N-di(2-hydroxyethyl)methylammonium bromide, abbreviated as CHEMAB and CDHAB, respectively, were synthesized in this work. Single crystal X-ray diffraction was used to study the intermolecular interactions of surfactants, and (1)H NMR and rheological measurements were employed to investigate the molecular arrangement and morphology of the wormlike micelles. The synergistic interactions of hydrogen bonding and more effective shielding of electrostatic repulsion contribute to the formation and viscoelastic behavior of wormlike micelles.

The dynamics of microcystis genotypes and microcystin production and associations with environmental factors during blooms in Lake Chaohu, China.

Lake Chaohu, which is a large, shallow, hypertrophic freshwater lake in southeastern China, has been experiencing lake-wide toxic Microcystis blooms in recent decades. To illuminate the relationships between microcystin (MC) production, the genotypic composition of the Microcystis community and environmental factors, water samples and associated environmental data were collected from June to October 2012 within Lake Chaohu. The Microcystis genotypes and MC concentrations were quantified using quantitative real-time PCR (qPCR) and HPLC, respectively.

Aggregation behavior of long-chain piperidinium ionic liquids in ethylammonium nitrate.

Micelles formed by the long-chain piperidinium ionic liquids (ILs) N-alkyl-N-methylpiperidinium bromide of general formula CnPDB (n = 12, 14, 16) in ethylammonium nitrate (EAN) were investigated through surface tension and dissipative particle dynamics (DPD) simulations. Through surface tension measurements, the critical micelle concentration (cmc), the effectiveness of surface tension reduction (Πcmc), the maximum excess surface concentration (Гmax) and the minimum area occupied per surfactant molecule (Amin) can be obtained. A series of thermodynamic parameters (DG0 m, DH0 m and DS0 m) of micellization can be calculated and the results showed that the micellization was entropy-driven.

Formation of worm-like micelles in mixed N-hexadecyl-N-methylpyrrolidinium bromide-based cationic surfactant and anionic surfactant systems.

Through the descriptive and rheological characterization of worm-like micelles formed by N-hexadecyl-N-methylpyrrolidinium bromide and sodium laurate, the formation and properties of the worm-like micelles were affected by the concentrations of sodium laurate and temperature. Additionally, cryogenic transmission electron microscopy images further validated the formation of worm-like micelles.

Study of micelle formation by fluorocarbon surfactant N-(2-hydroxypropyl)perfluorooctane amide in aqueous solution.

Micelles formed by fluorocarbon surfactant N-(2-hydroxypropyl)perfluorooctane amide in aqueous solution were studied through surface tension, dynamic light scatting (DLS), isothermal titration calorimetry (ITC), and dissipative particle dynamic (DPD) simulations. Through surface tension measurements, the effectiveness of surface tension reduction, the maximum surface excess concentration, and the minimum area occupied per surfactant molecule at the air/water interface were investigated. The critical micelle concentration (cmc) at different temperatures and a series of thermodynamic parameters (ΔG(m)0, ΔH(m)0, ΔS(m)0, ΔG(ads)0, ΔH(m)(A) and ΔC(p(m))0) of micellization were evaluated.