Investigation of the Photochromism of WO, TiO, and Composite WO-TiO Nanoparticles.

We report the synthesis of WO, TiO, and TiO-WO nanoparticles by a polyol route, with the objective of studying the influence of the preparation method on their photochromic properties. By combining transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and diffuse reflectance experiments, we show that low W concentrations and high ripening temperatures allow the preparation of WO nanoparticles with high photochromic efficiency. WO-TiO nanocomposites (NCs) prepared by the introduction of a TiO solution in a WO nanoparticle suspension exhibit a strong coloring photochromism, which is attributed to the TiO coating of the WO nanoparticles as it involves the formation of W-O-Ti oxo-bonds in place of W-ν defects.

Solvent-induced assembly of mono- and divalent silica nanoparticles.

Particles with attractive patches are appealing candidates to be used as building units to fabricate novel colloidal architectures by self-assembly. Here, we report the synthesis of one-patch silica nanoparticles, which consist of silica half-spheres whose concave face carries in its center a polymeric patch made of grafted polystyrene chains. The multistage synthesis allows for a fine control of the patch-to-particle size ratio from 0.

Transfer of multi-DNA patches by colloidal stamping.

Patchy particles have received great attention due to their ability to develop directional and selective interactions and serve as building units for the self-assembly of innovative colloidal molecules and crystalline structures. Although synthesizing particles with multiple dissimilar patches is still highly challenging and lacks efficient methods, these building blocks would open paths towards a broader range of ordered materials with inherent properties. Herein, we describe a new approach to pattern functional DNA patches at the surface of particles, by the use of colloidal stamps.

Linear Assembly of Two-Patch Silica Nanoparticles and Control of Chain Length by Coassembly with Colloidal Chain Stoppers.

The self-assembly of patchy nanosized building blocks is an efficient strategy for producing highly organized materials. Herein we report the chaining of divalent silica nanoparticles with polystyrene patches dispersed in tetrahydrofuran triggered by lowering the solvent quality. We study the influence of the patch-to-particle size ratio and show that the nature of the added nonsolvent, for example, ethanol, water, or salty water, and its volume fraction should be carefully adjusted.

Solvent-Induced Assembly of One-Patch Silica Nanoparticles into Robust Clusters, Wormlike Chains and Bilayers.

We report the synthesis and solvent-induced assembly of one-patch silica nanoparticles in the size range of 100-150 nm. They consisted, as a first approximation, of silica half-spheres of which the truncated face was itself concave and carried in its center a polymeric patch made of grafted polystyrene chains. The multistage synthesis led to 98% pure batches and allowed a fine control of the patch-to-particle size ratio from 0.