Polymer nanogels are used as colloidal stabilisers in emulsion polymerization. The nanogels were made by the covalent crosslinking of block copolymer micelles, the macromolecular building blocks of which were synthesized using a combination of catalytic chain transfer emulsion polymerization and reversible addition fragmentation chain-transfer (RAFT) of methacrylate monomers. The use of the nanogels in an emulsion polymerization led to anisotropic Janus and patchy colloids, where a latex particle was decorated by a number of patches on its surface. Control on the particle size and patch density was achieved by tailoring of the reaction conditions, such as varying the amount of nanogels, pH and salt concentration. Overall, the emulsion polymerization process in the presence of nanogels as stabilizers is shown to be a versatile and easily scalable route towards the fabrication of Janus and patchy polymer colloids.

We report an insight into the synthesis of silica-based "matchstick"-shaped colloidal particles, which are of interest in the area of self-propulsion on small length scales. The generation of aqueous emulsion droplets dispersed in an n-pentanol-rich continuous phase and their use as reaction centers allows for the fabrication of siliceous microparticles that exhibit anisotropy in both particle morphology, that is, a "matchstick" shape, and chemistry, that is, a transition-metal oxide-enriched head. We provide a series of kinetic studies to gain a mechanistic understanding and unravel the particle formation and growth processes. Additionally, we demonstrate the ability to select the aspect ratio of the "matchstick" particle in a straightforward manner.

Scattering enhancers are a class of nanomaterials used in every colored or white material surrounding us: from paints and inks to food and cosmetics to packaging and paper. Such hiding...

A simple, versatile approach for the roughening of polymer microparticles surfaces via a deformation technique in the presence of an inorganic matrix is presented here. The process consists of straightforward steps: (1) preparation of a bicomposite colloidal sol, that is polymer particles and inorganic particles, dispersed in a liquid, (2) drying of the mixture onto a suitable hard substrate, (3) heating the dried film above the glass transition temperature of the polymer, and (4) re-dispersion and chemical etching of the inorganic medium. The primary driver is capillary imbibition of the polymer melt into the inorganic colloidal template. In addition, 2D particle tracking experiments of dispersed rough particles in water were performed to probe the diffusional behaviour of the roughened objects in comparison with their smooth precursors. We show that, despite large scale roughness (up to 10% asperity size with respect to particle diameter), Stokes law is obeyed and the particle motion can be modelled simply with the Stokes-Einstein-Sutherland relation.

Microspheres with catalytic caps have become a popular model system for studying self-propelled colloids. Existing experimental studies involve predominantly “smooth” particle surfaces. In this study we determine the effect of irregular surface deformations on the propulsive mechanism with a particular focus on speed. The particle surfaces of polymer microspheres were deformed prior to depositing a layer of platinum which resulted in the formation of nanoscopic pillars of catalyst. Self-propulsion was induced upon exposure of the micromotors to hydrogen peroxide, whilst they were dispersed in water. The topological surface features were shown to boost speed (~2×) when the underlying deformations are small (nanoscale), whilst large deformations afforded little difference despite a substantial apparent catalytic surface area. Colloids with deformed surfaces were more likely to display a mixture of rotational and translational propulsion than their “smooth” counterparts.

<div> <div> <div> <p>Microspheres with catalytic caps have become a popular model system for studying self- propelled colloids. Existing experimental studies involve predominantly “smooth” particle surfaces. In this study we determine the effect of irregular surface deformations on the propulsive mechanism with a particular focus on speed. The particle surfaces were deformed prior to depositing a catalytic layer which resulted in the formation of nanoscopic pillars of catalyst. These features were shown to boost speed (~2×) when the underlying surface deformations are small (nanoscale), whilst large deformations afforded little difference despite a substantial apparent catalytic surface area. Colloids with deformed surfaces were more likely to display a mixture of rotational and translational propulsion than their “smooth” counterparts. </p> </div> </div> </div>

Facile synthetic methodology unlocks alkyl pyridinium acrylamide monomers for use in the construction of cucurbit[8]uril mediated dynamic, fluorescent hydrogels.

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