Template assisted preparation of high surface area macroporous supports with uniform and tunable nanocrystal loadings.

The incorporation of catalytic nanocrystals into macroporous support materials has been very attractive due to their increased catalyst mass activity. This increase in catalytic efficiency is attributed in part to the increased surface area to volume ratio of the catalysts and the use of complementary support materials that can enhance their catalytic activity and stability. A uniform and tunable coating of nanocrystals on porous matrices can be difficult to achieve with some techniques such as electrodeposition.

Role of interparticle interactions on microstructural and rheological properties of cellulose nanocrystal stabilized emulsions.

Hypothesis: Microstructural and rheological properties of particle-stabilized emulsions are highly influenced by the nanoparticle properties such as size and surface charge. Surface charge of colloidal particles not only influences the interfacial adsorption but also the interparticle network formed by the non-adsorbed particles in the continuous phase.

Experiments: We have studied oil-in-water emulsions stabilized by cellulose nanocrystals (CNCs) with two different degrees of surface charge.

Analysis of network formation and long-term stability in silica nanoparticle stabilized emulsions.

Emulsions are widely used in industrial applications, including in food sciences, cosmetics, and enhanced oil recovery. For these industries, an in depth understanding of the stability and rheological properties of emulsions under both static and dynamic conditions is vital to their successful application. Presented here is a thorough assessment of a model nanoparticle (NP) stabilized dodecane-in-water emulsion as a route to improved understanding of the relationship between NP properties, microstructure and droplet-droplet interactions on the stability and rheological properties of emulsions.

Stabilization of Oil-in-Water Emulsions with Noninterfacially Adsorbed Particles.

Classical (surfactant stabilized) and Pickering (particle stabilized) type emulsions have been widely studied to elucidate the mechanisms by which emulsion stabilization is achieved. In Pickering emulsions, a key defining factor is that the stabilizing particles reside at the liquid-liquid interface providing a mechanical barrier to droplet coalescence. This interfacial adsorption is achieved through the use of nanoparticles that are partially wet by both liquid phases, often through covalent surface modification of or surfactant adsorption to the nanoparticle surfaces.

Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading.

Functional colloidal materials were prepared by design through the self-assembly of nanoparticles (NPs) on the surfaces of polystyrene (PS) spheres with control over NP surface coverage, NP-to-NP spacing, and NP composition. The ability to control and fine tune the coating was extended to the first demonstration of the co-assembly of NPs of dissimilar composition onto the same PS sphere, forming a multi-component coating. A broad range of NP decorated PS (PS@NPs) spheres were prepared with uniform coatings attributed to electrostatic and hydrogen bonding interactions between stabilizing groups on the NPs and the functionalized surfaces of the PS spheres.

Microwave assisted formation of monoreactive perfluoroalkylsilane-based self-assembled monolayers.

We demonstrate the use of microwave radiation as a tool to accelerate the formation of perfluoroalkylsilane based self-assembled monolayers (SAMs) on silicon oxide surfaces. Surface coverage of these SAMs of monoreactive perfluoroalkylsilanes increased in proportion to the duration over which the solutions were heated by microwave radiation.

Electrochemically active nickel foams as support materials for nanoscopic platinum electrocatalysts.

Platinum is deposited on open-cell nickel foam in low loading amounts via chemical reduction of Pt cations (specifically, Pt(2+) or Pt(4+)) originating from aqueous Pt salt solutions. The resulting Pt-modified nickel foams (Pt/Ni foams) are characterized using complementary electrochemical and materials analysis techniques. These include electron microscopy to examine the morphology of the deposited material, cyclic voltammetry to evaluate the electrochemical surface area of the deposited Pt, and inductively coupled plasma optical emission spectrometry to determine the mass of deposited Pt on the Ni foam substrate.

Colloidal core-shell materials with 'spiky' surfaces assembled from gold nanorods.

A series of core-shell materials with 'spiky' surfaces are prepared through the self-assembly of gold nanorods onto polystyrene microspheres. Loading of the nanorods is finely tuned and the assemblies exhibit surface plasmon resonance properties. The 'spiky' surface topography of the assembled structures could serve as a versatile substrate for surface-enhanced Raman spectroscopy based sensing applications.