Enhancing catalytic potential of gold nanoparticles by linear and cross-linked polyurethane blending

This work describes the synthesis of gold nanoparticles (AuNPs) and their subsequent stabilization using a water-borne polyurethane matrix of micro-particles (Au/PU) by a heating method. Composites were prepared both from linear and cross-linked polyurethane (LPU and CPU). Catalytic activities of synthesized composites exhibiting 226.4 nm size were evaluated for reduction of Congo red dye. More than 90% Congo red degradation was achieved in just 6 minutes with Au/LPU. Under similar conditions, 30% of dye was degraded with Au/CPU composite in 5 minutes. The effects of different variables such as concentration of dye, catalyst dose and concentration of reagents have been optimized. The degradation process followed first order kinetics. The most efficient composite (Au/LPU) was characterized using UV/Vis, FTIR, SEM, XRD and DLS techniques. The excellent catalytic activity can be attributed to the polyurethane matrix making the dye available to catalytic sites (AuNPs).

This work describes the synthesis of gold nanoparticles (AuNPs) and their subsequent stabilization using a water-borne polyurethane matrix of micro-particles (Au/PU).

Preparation of hollow polyurethane microspheres with tunable surface structures via electrospraying technology

For the first time, electrospraying was employed to fabricate hollow polyurethane microspheres with controlled size and tunable surface morphology.

Polyamide 66 microspheres metallised with in situ synthesised gold nanoparticles for a catalytic application

A simple concept is proposed to metallise polyamide 66 (PA66) spherulite structures with in situ synthesised gold nanoparticles (Au NPs) using a wet chemical method. This cost-effective approach, applied to produce a PA66/Au NP hybrid material, offers the advantages of controlling the nanoparticle size, the size distribution and the organic-inorganic interactions. These are the key factors that have to be controlled to construct consistent Au nanostructures which are essential for producing the catalytic activities of interest. The hybrid materials obtained are characterised by means of scanning electron microscopy, transmission electron microscopy, attenuated total reflection-Fourier transform infrared spectrometry and X-ray diffraction spectrometry. The results show that PA66 microspheres obtained via the crystallisation process are coated with Au NPs of 13 nm in size. It was found that controlling the metal coordination is the key parameter to template the Au NPs on the spherulite surfaces. The preparation processes and the key factors leading to the formation of PA66 spherulites coated with Au NPs are discussed. Moreover, the efficiency of the coated spherulites as a potential catalyst is proved by demonstrating the reduction of methylene blue via UV-visible spectrometry.

Electroanalysis Using Macro-, Micro-, and Nanochemical Architectures on Electrode Surfaces. Bulk Surface Modification of Glassy Carbon Microspheres with Gold Nanoparticles and Their Electrical Wiring Using Carbon Nanotubes

Gold nanoparticles (approximately 30-60 nm in diameter) were deposited onto the surface of glassy carbon microspheres (10-20 microm) through electroless plating to produce bulk (i.e., gram) quantities of nanoparticle surface-modified microspheres. The gold nanoparticle-modified powder was then characterized by means of scanning electron microscopy and cyclic voltammetry. The voltammetric response of a macroelectrode consisting of a film of gold nanoparticle-modified glassy carbon microspheres, bound together and "wired-up" using multiwalled carbon nanotubes (MWCNTs), was investigated. We demonstrate that by intelligently exploiting both nano- and microchemical architectures and wiring up the electroactive centers using MWCNTs in this way, we can obtain macroelectrode voltammetric behavior while only using approximately 1% by mass of the expensive gold material that would be required to construct the equivalent gold film macrodisk electrode. The potential utility of electrodes constructed using chemical architectures such as this was demonstrated by applying them to the analytical determination of arsenic(III) concentration. An optimized limit of detection of 2.5 ppb was obtained.