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

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.

Download Full-text

A molecular dynamics simulation of boundary lubrication: The effect of n-alkanes chain length and normal load

Wear ◽

10.1016/j.wear.2013.01.052 ◽

2013 ◽

Vol 301 (1-2) ◽

pp. 62-69 ◽

Cited By ~ 30

Author(s):

Xuan Zheng ◽

Hongtao Zhu ◽

Buyung Kosasih ◽

A. Kiet Tieu

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Chain Length ◽

Boundary Lubrication ◽

Normal Load ◽

Dynamics Simulation

Download Full-text

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

ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels ◽

10.1115/icnmm2016-7962 ◽

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.

Download Full-text