Coarse-grained (CG) non-equilibrium molecular dynamics simulation was used to study the thermal conductivity of a cross-linked network composed of epoxy resin (E51) and polyether amine (PEA). By probing the mechanism of heat transfer in the cross-linked epoxy resin, we systematically explored the effects of the crosslinking degree, chain length and multi-functional groups of the curing agent on the thermal conductivity behavior. Our results indicate that the thermal conductivity is mainly dependent on the chain length and the functional groups of the curing agent. A shorter chain length and a curing agent with more functional groups contribute to higher thermal conductivity, while the crosslinking degree has a negligible effect. Moreover, it is revealed that the thermal conductivity is manipulated by the non-bonding interaction energy (E_pair) and the vibrational density. In general, our work could provide some guidelines for the design and fabrication of a cross-linked epoxy network with high thermal conductivity.

This paper reports the synthesis and antibacterial performance of a novel type of layer-structured montmorillonite (MMT) nanocomposite with cationic silica nanoparticles through an intercalating self-assembly method. The quaternary amine-functionalized SiO₂ nanoparticles were first prepared by grafting dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (PQAC) onto the surfaces of silica nanoparticles, and their chemical composition and structure were characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. Then, the reactant PQAC–SiO₂ nanoparticles were intercalated into the interlayers of MMT through electrostatic self-assembly to achieve the layer-structured MMT/PQAC–SiO₂ nanocomposites. The ordered and layered structural characteristics of the resulting nanocomposites were characterized using X-ray diffraction patterns and N₂ adsorption–desorption measurements and then confirmed by scanning electron microscopy and transmission electron microscopy. The optimum weight ratio of MMT/PQAC–SiO₂ nanoparticles was also achieved for the self-assembly fabrication of the nanocomposites on the basis of results mentioned above. The MMT/PQAC–SiO₂ nanoparticles gained an excellent thermal stability due to the intercalation of PQAC–SiO₂ nanocomposites into MMT and their onset degradation temperature was improved by 40 °C compared to that of PQAC–SiO₂ nanoparticles. Most of all, the nanocomposites presented a significant antibacterial effect against Escherichia coli and Staphylococcus aureus as the model microorganisms of Gram-negative and Gram-positive bacteria, respectively. This type of layered structural nanocomposite is expected to be applied for food packaging and containment of food materials, medical bandages for wound care, removal of environment pollutants like pesticides and phenol, etc.

This paper reports a new route to synthesize calcium carbonate (CaCO ₃ )-based nanoscale ionic materials (NIMs) via an in situ formation method to form the CaCO ₃ nanoparticles with a polysiloxane quaternary ammonium salt (PQAC) corona (PQAC-CaCO ₃ nanoparticles), followed by an ionic exchange reaction to fabricate a poly(ethylene glycol)-tailed sulfonate anion (NPEP) canopy. The chemical compositions and structures of the CaCO ₃ -based NIMs synthesized in this work were confirmed by Fourier-transform infrared spectroscopy and solid-state ¹³ C NMR spectroscopy. Transmission electron microscopic observation indicated that the CaCO ₃ -based NIMs presented a rhombohedral shape with a well-defined core-shell structure, and they also obtained an NPEP canopy with a thickness of 4–6 nm. X-ray powder diffraction investigation confirmed that the CaCO ₃ inner core had a calcite crystalline structure, whereas the NPEP canopy was amorphous. The NPEP canopy was found to show a characteristic crystallization–melting behaviour in the presence of the ion bonding with PQAC-CaCO ₃ nanoparticles according to the characterization of differential scanning calorimetry. Thermogravimetric analysis indicated that the CaCO ₃ -based NIMs achieved a high content of NPEP canopy as well as an improvement in thermal stability owing to the ion-bonding effect. Most of all, the CaCO ₃ -based NIMs demonstrated a liquid-like behaviour above the critical temperature in the absence of solvent. Moreover, the CaCO ₃ -based NIMs also showed a relatively high electrical conductivity with a temperature dependency due to the ionic conductive effect. This work will provide a more feasible and energy-saving methodology for the preparation of CaCO ₃ -based NIMs to promote their industrialization and extensive applications.