A ring stain is often an undesirable consequence of droplet drying. Particles inside evaporating droplets with a pinned contact line are transported toward the periphery by radial flow. In this paper, we demonstrate how suspensions of laponite can be used to control the radial flow inside picoliter droplets and produce uniform deposits. The improvement in homogeneity arises from a sol-gel trans...

oft materials, such as gels and colloidal glasses, often exhibit different rheological properties at ulk and microscopic scales as a result of their complex microstructure. This phenomenon has ecently been demonstrated for a gel-forming aqueous dispersion of Laponite clay Oppong et al. hys. Rev. E 78, 021405 2008 . For this material, microrheology reveals a significantly weaker el and a longer ...

In this paper we report the effect of the incorporation of nano-dimensional clay platelets, laponite, on the J-aggregation of a thiacyanine dye N,N'-dioctadecyl thiacyanine perchlorate (NK) assembled into Langmuir-Blodgett (LB) monolayers. pi-A isotherms and atomic force microscopic studies confirm the successful incorporation of clay platelets into the Langmuir monolayer of NK. J-aggregates of...

Using a fluorescence recovery after photobleaching (FRAP) technique, we present measurements of probe diffusion in a colloidal glass-a Laponite suspension. By varying the probe size over 2 orders of magnitude, as well as the concentration of the colloidal glass, we evidence and quantify the deviations of the probe diffusivity from the bulk Stokes-Einstein expectations. These experiments suggest...

The triblock copolymer Pluronic F127 (PF127) is frequently used in colloidal and pharmaceutical formulations. Concentrated aqueous solutions of PF127 (>15 wt %) are known to undergo thermogelling (i.e., a sol-to-gel transition upon heating), which is attributed to the formation of a volume-filling cubic array of micelles. Here, we report that thermogelling can occur at much lower PF127 concentr...

The addition of chitosan to silicate (Laponite) cross-linked poly(ethylene oxide) (PEO) is used for tuning nanocomposite material properties and tailoring cellular adhesion and bioactivity. By combining the characteristics of chitosan (which promotes cell adhesion and growth, antimicrobial) with properties of PEO (prevents protein and cell adhesion) and those of Laponite (bioactive), the result...

ess as: P r visibl niversity 2013.11.0 Abstract In this study, laponite and montmorillonite clays were found to be able to decompose rhodamine B upon visible light irradiation (k > 420 nm). Very interestingly, it was found that rhodamine B on laponite underwent a stepwise N-deethylation and its decomposition was terminated once rhodamine 110, as a decomposition product, was formed, whereas the ...

We study adsorption of two nonionic surfactants (C12E5 and C12E8) on a dispersed suspension of negatively charged laponite particles. First, we quantify adsorption, i.e. the amount of adsorbed molecules per gram of dried solid. Then, we show that contrast variation experiments under controlled conditions along the adsorption isotherm of the surfactant on dispersed laponite particles allow to de...

The process of dynamical arrest, leading to formation of different arrested states such as glasses and gels, along with the closely related process of aging, is central for both basic research and technology. Here we report on a study of the time-dependent structural evolution of two aqueous Laponite clay suspensions at different weight concentrations. Neutron diffraction experiments have been ...