Nanoparticles bearing a strongly bound polymer coating were formed by the thermal decomposition of iron pentacarbonyl in the presence of ammonia and polymeric dispersants. The dispersants consist of polyisobutylene, polyethylene, or polystyrene chains functionalized with tetraethylenepentamine, a short polyethyleneimine chain. Polystyrene-based dispersants were prepared with both graft and block copolymer architectures. Inorganic-organic core-shell nanoparticles were formed with all three types of dispersants. In addition, more complex particles were observed in the case of the polystyrene-based dispersants in 1-methylnaphthalene. The core material was identified as metallic iron, while the particle shells are formed from the polymeric dispersant which binds to the core. High-resolution TEM revealed evidence for crystallization within the polymer shell, possibly facilitated by chain alignment upon binding. The nanocomposites display room-temperature magnetic behavior ranging from superparamagnetic to ferromagnetic. The saturation magnetization and coercivity were found to depend on the diameter of the iron core.

The interaction of water monomers with a gold surface is investigated using density functional theory (DFT) to develop a better understanding of the response of a water molecule to an imposed electric field at the surface. Two gold surface orientations, Au(111) and Au(110), are studied. Multiple unique stable adsorption positions of water molecules are identified for each surface orientation, and the results are validated against existing theoretical and experimental data. The values of the adsorption energies do not vary by more than 0.06 eV, which suggests that the potential energy surface of the water molecule interacting with the gold electrode is relatively smooth. The projected density of states and the difference charge density analyses reveal that the interaction mechanism between the water molecule and the gold electrode is a partial exchange of charge rather than a chemical bonding. A normal electric field of magnitude between ±5.0 × 109 V/m is applied and its effect on the geometry and orientation of the water molecule is analyzed. The change in the geometry of the water molecule in response to the applied electric field shows a strong nonlinearity and asymmetry with respect to the magnitude and direction of the applied field. The interaction between the water monomer and Au electrode with/without the electric field is explained in terms of the interplay of Au–O, Au–OH, and electrostatic interactions. There is a significant difference between the dielectric response of the water molecule on the Au(111) and Au(110) surface that is related to the strength of the adsorption energy of the water monomer to both surfaces.

The future of integrated circuits with three‐dimensional chip architecture hinges on the development of practical solutions for the management of excessive amounts of heat generation. This requires new polymer–matrix composites (PMCs), with good processibility, high effective thermal conductivity (keff), and low but tailored electrical conductivity (σ). This article explores the synergy of hybrid fillers: (i) hexagonal boron nitride (hBN) platelets with different sizes and shapes; (ii) hBN platelets with carbon‐based fillers promoting the keff of the polyphenylene sulfide (PPS) composites. It explores the promotion of interconnectivity among the fillers in the PPS matrix, leading to higher keff, by the uses of hybrid fillers. It discusses using carbon‐based fillers as secondary fillers to tailor the PMCs' σ. Finally, it presents the effects of hybrid fillers on the PMCs' coefficient of thermal expansion. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Linear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. In this paper, we provide a comprehensive mathematical theory of voltammetry in electrochemical cells with unsupported electrolytes and for other situations where diffuse charge effects play a role, and present analytical and simulated solutions of the time-dependent PoissonNernst-Planck equations with generalized Frumkin-Butler-Volmer boundary conditions for a 1:1 electrolyte and a simple reaction. Using these solutions, we construct theoretical and simulated current-voltage curves for liquid and solid thin films, membranes with fixed background charge, and cells with blocking electrodes. The full range of dimensionless parameters is considered, including the dimensionless Debye screening length (scaled to the electrode separation), Damkohler number (ratio of characteristic diffusion and reaction times), and dimensionless sweep rate (scaled to the thermal voltage per diffusion time). The analysis focuses on the coupling of Faradaic reactions and diffuse charge dynamics, although capacitive charging of the electrical double layers is also studied, for early time transients at reactive electrodes and for nonreactive blocking electrodes. Our work highlights cases where diffuse charge effects are important in the context of voltammetry, and illustrates which regimes can be approximated using simple analytical expressions and which require more careful consideration.