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We investigated the effect of Fe3O4 nanoparticle orientation on the magnetic properties of hybrid polymer nanocomposite thin films. A multilayer thin film consisting of alternating layers of polymers and assembled iron oxide nanoparticles was prepared by spin coating and Langmuir–Blodgett techniques. Transmission electron microscopy and neutron reflectivity measurements were employed to determine structural information related to the lateral orientation of the Fe3O4 nanoparticle monolayer and the layered architecture along the depth of the multilayer, respectively. The magnetic properties of the hybrid multilayer were characterized by SQUID magnetometry and compared with the properties of a spin-coated polymer nanocomposite thin film containing homogenously dispersed Fe3O4 nanoparticles. We found that the closely-packed monolayer structure of the Fe3O4 nanoparticles changed the magnetic properties on account of the dipolar interactions between particles, whereas the homogeneously-dispersed nanoparticles embedded in the polymer matrix exhibited zero remanent magnetization and coercivity due to isolation of the nanoparticles and lack of dipolar interactions.

Here, we report a simple and fast synthetic route to Ag/AgBr hybrid nanostructures prepared by reducing AgBr nanoparticles synthesized by the reaction of Ag+ with Br− in the presence of polyethyleneimine (PEI). By controlling the experimental conditions including reaction temperature and amount of reducing agent, we could easily control the morphology and composition of a variety of Ag/AgBr hybrid nanostructures including Ag nanoparticles decorated with AgBr nanoparticles and hollow cage-like Ag-rich nanostructures. The Ag/AgBr hybrid nanostructures exhibited enhanced photocatalytic activity and recyclability for decomposing methylene blue (MB) under visible-light illumination because of a small bandgap (2.6 eV) and strong SPR effect. In particular, we found that the Ag/AgBr hybrid nanostructures showed a photocatalytic reaction rate that was 1000 times faster than commercial TiO2 (P-25). In addition, the Ag/AgBr hybrid nanostructures had a higher photocatalytic activity compared to Ag/AgCl hybrid nanostructures towards the decomposition of methyl orange (MO) under visible light illumination.

Synthesizing Cu nanocrystals with tunable sizes in the sub-100 nm regime and good uniformity is essential for their applications in microelectronics. In this paper, we demonstrate a facile and scalable synthetic route to uniform Cu nanocrystals with tunable sizes in the range of 20–100 nm based on an ethylene glycol (EG)-assisted synthetic method with appropriate alkylamine and fatty acid as surfactant and co-surfactant, respectively. In this approach, the size of Cu nanocrystals could be readily controlled by varying alkyl chain length of alkylamine, fatty acid, or both. We also demonstrate that these Cu nanocrystals can be successfully applied to the fabrication of solution-processed electrodes for organic field-effect transistors with reasonably high hole mobility.

This work describes a simple and aqueous-phase route for the synthesis of Cu nanowires (Cu NWs) having a long length of 140−180 μm, a high aspect ratio of more than 350, and long-term stability. High-quality Cu NWs were synthesized by reduction of CuCl2 with ascorbic acid in the presence of branched polyethyleneimine (BPEI) in an aqueous solution at 90 °C. The synthesized uniform Cu NWs showed long-term stability without the formation of Cu oxides on the surface of the NWs after being stored at room temperature for 40 days. Interestingly, we found that Cl− in the reacting solution played a key role in the formation of long Cu NWs. We also investigated the influence of various experimental conditions including the weight ratio of BPEI/CuCl2, the pH of the reacting solution, and the reaction temperature on the length, morphology, and stability of Cu NWs.

This study explores the facile controlled-synthesis and localized surface plasmonic properties of Au nanoplates. Au nanoplates were synthesized via a reaction of HAuCl4 with branched polyethyleneimine (BPEI) in the presence of urea at a reaction temperature as low as 30 °C. Structural characterizations revealed that the synthesized Au nanoplates had an average lateral size of around 2–8 μm and a thickness of around 40 nm, plus they were highly crystalline in spite of the low reaction temperature. Studies of the growth factors for Au nanoplates showed that the PEI morphology, molar ratio of BPEI/HAuCl4, pH of the reaction solution, and concentration of urea all played important roles in the formation of thin Au nanoplates. With a low BPEI/HAuCl4 ratio or under acidic conditions, thick Au plates were synthesized, whereas Au nanoparticles around 10–20 nm were observed with a high BPEI/HAuCl4 ratio or under basic conditions. When the synthesis was conducted in the absence of urea, thick Au nanoplates were synthesized, indicating that urea can serve as a capping agent for thin Au nanoplates. The resulting Au nanoplates also exhibited an enhanced surface-enhanced Raman scattering (SERS) signal when compared with Au nanoparticles due to their sharp corners and edges.