Polymeric microparticles with hexagonal surface patterns comprising of colloids or dimples were fabricated using photocurable emulsion droplets. Colloidal silica particles within the interior of the photocurable emulsion droplets formed two-dimensional (2D) crystals at the droplet surface by anchoring on the emulsion interface, and the resulting composite structures were captured by rapid photo...

LUDOX® colloidal silicas are aqueous dispersions of very small silica particles in the low nanometer size range. Many grades are offered in this family, giving broad flexibility for specific performance targets. This bulletin aims to inform the formulator about the unique properties of LUDOX® colloidal silica and to offer starting points for applications such as anticorrosive coatings and archi...

We report on a single-step coating process and the resulting colloidal stability of silica-coated spindle-type hematite nanoparticles (NPs) decorated with a layer of poly(acrylic acid) (PAA) polyelectrolyte chains that are partially incorporated into the silica shell. The stability of PAA coated NPs as a function of pH and salt concentration in water was compared to bare hematite particles and ...

Polymerization rates of silica at various concentrations and pHs have been studied via nephelometry. The ability and potency of ultrasonic radiation on the coagulation process in aqueous samples with and without silica colloidal particles have been extensively investigated. Factors affecting the rate and filtration volume such as silica concentration, time of radiation, temperature, and fre...

Disc centrifuge photosedimentometry (DCP) with fluids of different densities is used to simultaneously determine the particle size and effective density of spherical silica particles. Incorporation of a calibrated infrared pyrometer into a DCP instrument is shown to enhance the measurement capability of the DCP technique by correcting for the temperature dependence of the spin fluid's density a...

A new microfluidic approach to preparing anisotropic colloidal photonic crystal microparticles is developed and the self-assembly kinetics of colloidal nanoparticles is discussed. Based on the “coffee ring” effect in the self-assembly process of colloidal silica particle in strong solvent extraction environment, we successfully prepared anisotropic photonic crystal microparticles with different...

We report a comprehensive study of laser-initiated, liquid-assisted colloidal (LILAC) lithography, and illustrate its utility in patterning silicon substrates. The method combines single shot laser irradiation (frequency doubled Ti-sapphire laser, 50fs pulse duration, 400nm wavelength) and medium-tuned optical near-field effects around arrays of silica colloidal particles to achieve 3-D surface...

Thermal wetting can simply, selectively and reversibly join patchy particles into clusters (2D and 3D) and also colloidal crystals over the narrow temperature range of 1-2 °C. This is demonstrated with Janus particles (gold half-coated silica spheres) immersed in a binary mixture of water/2,6-lutidine, such that the relative strength of gold-gold bonding through hydrophobic interaction and sili...

Water-cast films of two ethers of cellulose, hydroxypropylcellulose (HPC) and hydroxyethylcellulose (HEC), with dispersed silica particles, were deposited on flat substrates. X-ray specular reflectivity was used to characterize the structure of these solid ca. 1000 Å thick films as a function of the added colloidal fraction. It was shown that the structural changes resulting from increasing amo...

We describe a six-step method for making colloidal clusters of 2, 3, or 4 silica particles with a radius of 1.2 microm. This method, originally described by Manoharan et al. (Manoharan, V. N.; Elsesser, M. T.; Pine, D. J. Science 2003, 301, 483), is based on the encapsulation of silica spheres in emulsion droplets. The originality of our work lies in the preparation of monodisperse emulsions, w...