Robust superhydrophobic self-cleaning coating prepared by silane modified multi-walled carbon nanotubes: A combined experimental and molecular dynamics study.

As a functional material, superhydrophobic coating has been widely studied in the field of self-cleaning. However, obtaining superhydrophobic coatings with robustness through simple preparation processes remains a challenge. In this paper, a robust superhydrophobic coating is prepared based on multi-walled carbon nanotubes modified by octyltrimethoxysilane, and its performance and hydrophobic mechanism are studied by experiments and molecular dynamics simulation. The superhydrophobic coating is prepared by one-step spraying method. The coating is characterized and analyzed by scanning electron microscopy and Fourier transform infrared spectroscopy, and the properties of the coating are tested by experiments. Molecular dynamics simulation is used in the study to construct a molecular model system, and the molecular modification mechanism and coating wettability are simulated under the COMPASSII force field. The results show that octyltrimethoxysilane successfully modified carbon nanotubes, and the hydroxyl groups at the head of the molecular chain are bound to the surface of the carbon nanotubes in the form of hydrogen bonds, while the tail of the molecular chain is far away from the surface. After modification, the surface of carbon nanotubes changed from hydrophilic to hydrophobic. The prepared superhydrophobic coating not only has excellent self-cleaning properties, but also exhibits corrosion resistance to acid and alkali solutions. The coating still has superhydrophobic when the wear length is in the range of 400 cm. It can be seen that a robust superhydrophobic self-cleaning coating is successfully prepared by a simple one-step spraying method. The modification mechanism and the hydrophobic mechanism of the coating were obtained by the combination of experiment and molecular dynamics simulation, which provided theoretical support for the superhydrophobic of the coating at the micro level.

Thermal transport of graphene-C3B superlattices and van der Waals heterostructures: a molecular dynamics study.

Two-dimensional (2D) materials have attracted more and more attention due to their excellent properties. In this work, we systematically explore the heat transport properties of Graphene-C3B (GRA-C3B) superlattices and van der Waals (vdW) heterostructures using molecular dynamics method. The effects of interface types and heat flow directions on the in-plane interfacial thermal resistance (ITRip) are analyzed. Obvious thermal rectification is detected in the more energy stable interface, GRA zigzag-C3B zigzag (ZZ) interface, which also has the minimum value of ITRip. The dependence of the superlattices thermal conductivity (k) of the ZZ interface on the period length (lp) is investigated. The results show that when thelpis 3.5 nm, thekreaches a minimum value of 35.52 W m-1K-1, indicating a transition stage from coherent phonon transport to incoherent phonon transport. Afterwards, the effects of system size, temperature, coupling strength and vacancy defect on the out-of-plane interfacial thermal resistance (ITRop) are evaluated. With the increase of temperature, coupling strength and vacancy defect, ITRopare found to reduce effectively due to the enhanced Umklapp phonon scattering and increased probability of energy transfer. Phonon density of states and phonon participation ratio is evaluated to reveal phonon behavior during heat transport. This work is expected to provide essential guidance for the thermal management of nanoelectronics based on 2D monolayer GRA and C3B.

Interfacial thermal transport of graphene/ß-Ga2O3 heterojunctions: a molecular dynamics study with a self-consistent interatomic potential.

Graphene/ß-Ga2O3 heterojunctions are widely used in high-power and high-frequency devices, for which thermal management is vital to the device operation and life. Here we apply molecular dynamics simulation to calculate the interfacial thermal resistance (ITR) between graphene and ß-Ga2O3. Based on the rigid ion model, a self-consistent interatomic potential with a set of parameters that can well reproduce the basic physical properties of crystal ß-Ga2O3 is fitted. Using this potential, the effects of model size, interface type, temperature, vacancy defects and graphene hydrogenation on the ITR of graphene/ß-Ga2O3 heterojunctions are evaluated. The results show that there is no obvious dependence of ITR on the size of graphene and ß-Ga2O3. It is reported that the ITR values of the (100), (010) and (001) interfaces are 7.28 ± 0.35 × 10-8 K m2 W-1, 6.69 ± 0.44 × 10-8 K m2 W-1 and 5.22 ± 0.35 × 10-8 K m2 W-1 at 300 K, respectively. Both temperature increase and vacancy defect increase can prompt the energy propagation across graphene/ß-Ga2O3 interfaces due to the enhancement of phonon coupling. In addition, graphene hydrogenation provides new channels for in-plane and out-of-plane phonon coupling, and thus reduces the ITR between graphene and ß-Ga2O3. This study provides basic strategies for the thermal design and management of graphene/ß-Ga2O3 based photoelectric devices.

Geometrical nonlinear stability analyses of cable-truss domes.

The nonlinear finite element method is used to analyze the geometrical nonlinear stability of cable-truss domes with different cable distributions. The results indicate that the critical load increases evidently when cables, especially diagonal cables, are distributed in the structure. The critical loads of the structure at different rise-span ratios are also discussed in this paper. It was shown that the effect of the tensional cable is more evident at small rise-span ratio. The buckling of the structure is characterized by a global collapse at small rise-span ratio; that the torsional buckling of the radial truss occurs at big rise-span ratio; and that at proper rise-span ratio, the global collapse and the lateral buckling of the truss occur nearly simultaneously.