Nanoscale Azide Polymer Functionalization: A Robust Solution for Suppressing the Carbon Nanotube–Polymer Matrix Thermal Interface Resistance

The large thermal resistance across the carbon nanotube (CNT)–polymer matrix interface is a limiting factor for achieving polymer composites with high thermal conductivities. Using equilibrium molecular dynamics simulations we show that an azide-terminated aromatic polymer HLK5 (C₂₂H₂₅O₃N₃) functionalized onto the CNT sidewall can efficiently decrease the thermal resistance between the nanotube and different types of polymer matrices (polystyrene, epoxy, and polyethylene). The HLK5 functionalization can also significantly decrease the CNT–CNT junction resistance. Compared with hydroxyl and octane functionalizations, the HLK5 one alters less the high intrinsic CNT thermal conductivity at the same surface coverage ratio. By revealing the important role played by the atomistic van der Waals interactions in attaining these key results, our study brings a new perspective in the nanoscale design of advanced CNT–polymer materials

Novel DABCO Based Ionic Liquids: Green and Efficient Catalysts with Dual Catalytic Roles for Aqueous Knoevenagel Condensation

Four novel basic ionic liquids (ILs), based on 1,4-diazobicyclo[2.2.2]­octane (DABCO) and 3-chloro-1,2-propanediol, have been introduced as catalysts for Knoevenagel condensation. These catalysts are applicable to a wide range of aromatic/heteroaromatic aldehydes with α-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water at room temperature, and they afford the products in excellent yields within short times. These reactions are operationally simple, and the desired products can be separated directly from the reaction mixture without further purification. A possible reaction mechanism was proposed, and the relevant evidence was given. In addition, the ionic liquids used can be regenerated and recycled several times without significant loss of activity. Furthermore, the novel ILs could be efficiently used in a step of atorvastatin synthesis

Novel Multiple-Acidic Ionic Liquids: Catalysts for Environmentally Friendly Benign Synthesis of <i>trans</i>-β-Nitrostyrenes under Solvent-Free Conditions

A series of novel multiple-acidic ionic liquids, sulfated from the low-cost starting material 2-aminoethanol, were introduced as catalysts for the Henry reaction of versatile aldehydes and nitroalkane under solvent-free conditions. The ionic liquid with hydrogen sulfate as a counteranion showed the best catalytic efficiency and gave the corresponding <i>trans</i>-β-nitrostyrenes in good to excellent yields. More importantly, the ionic liquid catalyst could be readily recovered and reused six times without considerable loss of its catalytic activity

Thermal Transport across Surfactant Layers on Gold Nanorods in Aqueous Solution

Ultrafast transient absorption experiments and molecular dynamics simulations are utilized to investigate the thermal transport between aqueous solutions and cetyltrimethylammonium bromide (CTAB)- or polyethylene glycol (PEG)-functionalized gold nanorods (GNRs). The transient absorption measurement data are interpreted with a multiscale heat diffusion model, which incorporates the interfacial thermal conductances predicted by molecular dynamics. According to our observations, the effective thermal conductance of the GNR/PEG/water system is higher than that of the GNR/CTAB/water system with a surfactant layer of the same length. We attribute the enhancement of thermal transport to the larger thermal conductance at the GNR/PEG interface as compared with that at the GNR/CTAB interface, in addition to the water penetration into the hydrophilic PEG layer. Our results highlight the role of the GNR/polymer thermal interfaces in designing biological and composite-based heat transfer applications of GNRs, and the importance of multiscale analysis in interpreting transient absorption data in systems consisting of low interfacial thermal conductances