scholarly journals Evaluation of Surface Energy by Molecular Dynamics Simulation and Discussion about Cleavage Fracture in .ALPHA.-Al2O3

2004 ◽  
Vol 112 (1301) ◽  
pp. 46-49 ◽  
Author(s):  
Shin-ichi TAKEMATSU ◽  
Takashi MIZUGUCHI ◽  
Hideharu NAKASHIMA ◽  
Ken-ichi IKEDA ◽  
Hiroshi ABE
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Surface Energy ◽  
Cleavage Fracture ◽  
Dynamics Simulation

scholarly journals Comparative Studies on Water Self-Diffusivity Confined in Graphene Nanogap: Molecular Dynamics Simulation

2016 ◽  
Author(s):  
Mohammad Moulod ◽  
Gisuk Hwang
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Surface Energy ◽  
Water Transport ◽  
Surface Interactions ◽  
Bulk Water ◽  
Water Desalination ◽  
Atomic Scale ◽  
Dynamics Simulation ◽  
Interatomic Potentials

Fundamental understanding of the water in graphene is crucial to optimally design and operate the sustainable energy, water desalination, and bio-medical systems. A numerous atomic-scale studies have been reported, primarily articulating the surface interactions (interatomic potentials) between the water and graphene. However, a systematic comparative study among the various interatomic potentials is rare, especially for the water transport confined in the graphene nanostructure. In this study, the effects of different interatomic potentials and gap sizes on water self-diffusivity are investigated using the molecular dynamics simulation at T = 300 K. The water is confined in the rigid graphene nanogap with the various gap sizes Lz = 0.7 to 4.17 nm, using SPC/E and TIP3P water models. The water self-diffusivity is calculated using the mean squared displacement approach. It is found that the water self-diffusivity in the confined region is lower than that of the bulk water, and it decreases as the gap size decreases and the surface energy increases. Also, the water self-diffusivity nearly linearly decreases with the increasing surface energy to reach the bulk water self-diffusivity at zero surface energy. The obtained results provide a roadmap to fundamentally understand the water transport properties in the graphene geometries and surface interactions.

scholarly journals Quantitative Study on Solubility Parameters and Related Thermodynamic Parameters of PVA with Different Alcoholysis Degrees

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3778
Author(s):  
Siqi Chen ◽  
Hao Yang ◽  
Kui Huang ◽  
Xiaolong Ge ◽  
Hanpeng Yao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Surface Energy ◽  
Chain Length ◽  
Dynamics Simulation ◽  
Solubility Parameters ◽  
Specific Surface Energy ◽  
Surface Parameters ◽  
Surface And Interface ◽  
Dispersive Surface Energy

In recent years, inverse gas chromatography (IGC) and molecular dynamics simulation methods have been used to characterize the solubility parameters and surface parameters of polymers, which can provide quantitative reference for the further study of the surface and interface compatibility of polymer components in the future. In this paper, the solubility parameters and surface parameters of two kinds of common alcoholysis, PVA88 and PVA99, are studied by using the IGC method. The accuracy of the solubility parameters obtained by the IGC experiment is verified by molecular dynamics simulation. On the basis of this, the influence of repeated units of polyvinyl alcohol (PVA) on solubility parameters is studied, so as to determine the appropriate chain length of the PVA for simulation verification calculation. The results show that the solubility parameters are not much different when the PVA chain length is 30 and above; the numerical trends of the solubility parameters of PVA88 and PVA99 at room temperature are the same as the results of molecular dynamics simulation; the dispersive surface energy γsd and the specific surface energy γssp are scattered with the temperature distribution and have a small dependence on temperature. On the whole, the surface energy of PVA99 with a higher alcoholysis degree is higher than that of PVA88 with a lower alcoholysis degree. The surface specific adsorption free energy (∆Gsp) indicates that both PVA88 and PVA99 are amphoteric meta-acid materials, and the acidity of PVA99 is stronger.

Molecular dynamics simulation study on surface structure and surface energy of anatase

2010 ◽  
Vol 18 (7) ◽  
pp. 075002 ◽  
Author(s):  
Dai-Ping Song ◽  
Ming-Jun Chen ◽  
Ying-Chun Liang ◽  
Chun-Ya Wu ◽  
Zhi-Jiang Xie ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Surface Energy ◽  
Surface Structure ◽  
Simulation Study ◽  
Dynamics Simulation

Characteristics of the Water Meniscus at AFM Tip for Various Surface Energy

2008 ◽  
Author(s):  
Hojin Choi ◽  
Jung Yun Kim ◽  
Seungdo Hong ◽  
Joonkyung Jang ◽  
Man Yeong Ha
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Surface Energy ◽  
Equilibrium State ◽  
Atomic Force Microscope ◽  
Capillary Force ◽  
Flat Surface ◽  
Dynamics Simulation ◽  
Atomic Force ◽  
Water Meniscus

The atomic force microscope (AFM), invented by Binning et al [1], has become a useful tool for its application in various fields of research. Even though AFM shows outstanding performance, one problem is the large adhesion forces due to the formation of a water meniscus in ambient condition. Therefore, it is important to understand the properties of the water meniscus. In previous studies, a theoretical method or Monte Carlo method was used to model the water meniscus problem with the assumption of thermodynamic equilibrium. But the physical phenomenon, occurs in a real AFM environment, is difficult to reach the thermodynamic equilibrium state due to a continuous variation of the water meniscus structure. Through two methods, addressed upon, only shows the equilibrium state, they have many difficulties to make clear the mechanism of a water meniscus formation. Because it is also troublesome to simulate the formation process of a water meniscus, most of researches have only investigated the properties of the water meniscus. Molecular Dynamics Simulation (MD) is the most suitable method for our needs. We can not only obtain the capillary force of the water meniscus, but also visualize the forming mechanism of the water meniscus. For these reasons, the water meniscus is expected to be understood easier. We performed a molecular dynamics simulation of the water meniscus that forms between an atomic force microscope (AFM) tip and a flat solid surface. We obtained the density profile and the capillary force of the nano-scale meniscus. We also examined the structure change in the meniscus by scanning the AFM tip at various distances between the AFM tip and the flat surface. In the case of a hydrophilic tip and a hydrophobic flat surface, the water meniscus changes from convex to concave as the surface energy of the flat surface increases. Using Young-Laplace equation, we obtain the capillary force of the water meniscus. In the case of a hydrophilic tip and a hydrophilic flat surface, the capillary force decreases as the distance between the AFM tip and the flat surface increases. We also examined the radius of the water meniscus. As the distance increases, the radius gets smaller. At a distance over d = 2.5nm, the radius of the water meniscus starts to fluctuate due to the instability of the water meniscus becoming narrow.

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