TEM and HRTEM evidence for the role of ligands in the formation of shape-controlled platinum nanoparticles

The morphology of platinum nanoparticles synthesized using an organometallic approach from PtMe(2) (C(8) H(12) ) is influenced by the nature of the ligands used as stabilizing agents. The use of long alkyl chain amines leads to the formation of multipodal nanoparticles that transform into compact nano-objects, adopting cubic, truncated cubic, or cuboctahedral shapes. In contrast, the use of diamine ligands allows the growth of compact (111) arrowlike faces, forming polycrystalline nanoparticles of an overall desert-rose aspect. Different reaction parameters are studied ([ligand]/[metal] ratio, temperature, solvent identity) in order to optimize the various shapes.

Selective decoration of metal nanoparticles inside or outside of organic microstructures via self-assembly of resorcinarene

A facile template method was described for the decoration of organic microtubes with various nanoparticles (NPs), which was achieved in a straightforward "mix" process in the presence of templates and resorcinarene-functionalized nanoparticles (AuNPs, AgNPs, PtNPs, and PdNPs). A combination of UV-visible spectra and Fourier transform-infrared spectroscopy, transmission electron microscopy, field emission scanning electron microscopy, X-ray diffraction measurements, contact angle experiment, and energy dispersive X-ray spectroscopy was used for analysis. Interestingly, it was found that NPs could be encapsulated into the microtubes during the process of resorcinarene self-assembly. As a model system, AuNP-loaded microtubes were investigated and discussed, and loaded nanoparticles with a narrow size distribution were observed. Furthermore, AuNP-decorated microsheets could also be obtained by the assembly of resorcinarene with hydrazide groups. Remarkably, it was also observed that the incorporated NPs could be redispersed by treating the NP-loaded microtubes, which made it possible to realize the uptake and release of given nanoparticles. This procedure was scalable to diverse resorcinarene-based self-assemblies and applicable to various metal nanoparticles that decorate by resorcinarenes.

Insight into the Broad Field of Polymer Nanocomposites: From Carbon Nanotubes to Clay Nanoplatelets, via Metal Nanoparticles

Highly ordered polymer nanocomposites are complex materials that display a rich morphological behavior owing to variations in composition, structure, and properties on a nanometer length scale. Metal-polymer nanocomposite materials are becoming more popular for applications requiring low cost, high metal surface areas. Catalytic systems seem to be the most prevalent application for a wide range of metals used in polymer nanocomposites, particularly for metals like Pt, Ni, Co, and Au, with known catalytic activities. On the other hand, among the most frequently utilized techniques to prepare polymer/CNT and/or polymer/clay nanocomposites are approaches like melt mixing, solution casting, electrospinning and solid-state shear pulverization. Additionally, some of the current and potential applications of polymer/CNT and/or polymer/clay nanocomposites include photovoltaic devices, optical switches, electromagnetic interference (EMI) shielding, aerospace and automotive materials, packaging, adhesives and coatings. This extensive review covers a broad range of articles, typically from high impact-factor journals, on most of the polymer-nanocomposites known to date: polymer/carbon nanotubes, polymer/metal nanospheres, and polymer/clay nanoplatelets composites. The various types of nanocomposites are described form the preparation stages to performance and applications. Comparisons of the various types of nanocomposites are conducted and conclusions are formulated.

Formation and Stabilization of Anisotropic Palladium and Platinum Nanoparticles in Aqueous Polymer Solution Using Microwave Irradiation

Anisotropic palladium and platinum nanoparticles were synthesized by reduction of the corresponding metal ions with hydrazine using polyacrylamide as a stabilizing agent in aqueous medium under microwave irradiation. The formation of particles was confirmed by UV-visible spectroscopy. The size and shape of the particles were determined using transmission electron microscopy. Rapid microwave heating resulted in ‘star-shaped’ palladium nanoparticles, but platinum nanoparticles were observed to be spherical with a distinctly visible 3–4 nm coating of polyacrylamide on their surface, which was not observed for the palladium particles. The Pt nanoparticles were used as a catalyst in the redox reaction.