Molecular dynamics simulations of wetting behavior of water droplets on polytetrafluorethylene surfaces

Chen, Shuai; Wang, Jiadao; Ma, Tianbao; Chen, Darong

doi:10.1063/1.4868641

Cited by 50 publications

(17 citation statements)

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“…In recent years, the two states are intensively investigated in the progress in superhydrophobic surface developments, [7][8][9] and the results of the molecular simulations show that the fluid-solid interaction intensity has a dominant influence on the relationship between the two states, in relation to the wetting phenomena. [10][11][12][13][14][15] However, under the influence of a varying fluid-solid interaction, the local thermodynamic state of the liquid in the vicinity of the solid surface having nanometer-scale structures, which is intimately involved in the interfacial phenomena, and the transition mechanism between the two states based on the local thermodynamic quantities have yet to be revealed in detail from a molecular point of view.…”

Section: Introductionmentioning

confidence: 99%

Local pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit pore obtained by the perturbative method

Fujiwara

Shibahara

2015

The Journal of Chemical Physics

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A classical molecular dynamics simulation was conducted for a liquid-solid interfacial system with a nanometer-scale slit pore in order to reveal local thermodynamic states: local pressure components and interfacial tensions of a liquid film in the vicinity of the slit. The simulation also examined the transition mechanism between the two states of the liquid film: (a) liquid film on the slit and (b) liquid film in the slit, based on the local thermodynamic quantities from a molecular point of view. An instantaneous expression of the local pressure components and interfacial tensions, which is based on a volume perturbation, was presented to investigate time-dependent phenomena in molecular dynamics simulations. The interactions between the particles were described by the 12-6 Lennard-Jones potential, and effects of the fluid-solid interaction intensity on the local pressure components and interfacial tensions of the fluid in the vicinity of the slit were examined in detail by the presented perturbative method. The results revealed that the local pressure components tangential to the solid surface in the vicinity of the 1st fluid layer from the solid surface are different in a two dimensional plane, and the difference became pronounced in the vicinity of the corner of the slit, for cases where the fluid-solid interaction intensities are relatively strong. The results for the local interfacial tensions of the fluid inside the slit suggested that the local interfacial tensions in the vicinity of the 2nd and 3rd layers of the solid atoms from the entrance of the slit act as a trigger for the transition between the two states under the influence of a varying fluid-solid interaction.

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Section: Introductionmentioning

confidence: 99%

Local pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit pore obtained by the perturbative method

Fujiwara

Shibahara

2015

The Journal of Chemical Physics

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“…Molecular dynamics (MD) simulation is a powerful tool to obtain the microscopic details of atomistic system, and it has been widely used to investigate the physiochemistry of surface and the wetting behaviors [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] . One of the key issue in MD simulation is the potential models adopted to describe the interaction between molecules.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

Hakim

Kurniawan

Indahyanti³

et al. 2021

ICS Phys. Chem.

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The underlying principle of surface wettability has obtained great attentions for the development of novel functional surfaces. Molecular dynamics simulations has been widely utilized to obtain molecular-level details of surface wettability that is commonly quantified in term of contact angle of a liquid droplet on the surface. In this work, the sensitivity of contact angle calculation at various degrees of surface hydrophilicity to the adopted potential models of water: SPC/E, TIP4P, and TIP5P, is investigated. The simulation cell consists of a water droplet on a structureless surface whose hydrophilicity is modified by introducing a scaling factor to the water-surface interaction parameter. The simulation shows that the differences in contact angle described by the potential models are systematic and become more visible with the increase of the surface hydrophilicity. An alternative method to compute a contact angle based on the height of center-of-mass of the droplet is also evaluated, and the resulting contact angles are generally larger than those determined from the liquid-gas interfacial line.

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“…For instance, the surface functional groups of a polymer surface with amino, carboxyl, ammonium, and carboxylate groups and oxidation exhibit water contact angles ranging from ∼20 to ∼120°. − Modeling and simulation are useful to predict the surface wettability properties especially when tuning the surface texturing and chemical properties are paramount to facilitate good coating design. Molecular dynamics (MD) simulations can accurately predict the wetting behaviors of water on polymers based on their atomic structures and dynamics, − which provide useful guidelines to experimental fabrication.…”

Section: Introductionmentioning

confidence: 99%

Multiscale Modeling to Predict the Hydrophobicity of an Experimentally Designed Coating

et al. 2020

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Fine-tuning surface energies of coatings through experimental trial and error can be very tedious and time-consuming. The use of a reliable theoretical model can provide useful guidelines for experimental and formulation design for surface hydrophobicity. In this work, we perform multiscale modeling with molecular dynamics (MD) simulations, theoretical models, and computational fluid dynamics (CFD) simulations to investigate the wetting and sliding behavior of a water droplet on experimentally fabricated coatings. The wetting behavior of a water droplet on untreated polydimethylsiloxane (PDMS) surface and PDMS surface functionalized with hydroxyl and fluoride groups is studied by MD simulations. MD simulation results show that water contact angle (WCA) increases with increasing length of fluorocarbon chains, and this is in good agreement with experimental measurement of PDMS surface functionalized with C8F17. A theoretical model using the results from the MD simulation and inputs from experimental measurements of surface morphology is further proposed to predict the WCA of functionalized microstructured PDMS surface. The validated theoretical model shows that, though increasing the filler concentration aids in enhancing surface hydrophobicity, the separation distance between neighboring features decreases, weakening the hydrophobicity property and indicating there is an optimal filler concentration for the most hydrophobic surface. To perform multiscale modeling to predict the hydrophobicity of coating, the CFD model is constructed to predict droplet sliding and bouncing on an inclined surface in the macroscopic scale by using the WCA from MD simulations and theoretical model as input. The sliding and bouncing behaviors in CFD simulations are well-matched with the experimental observations on different hydrophobic surfaces. This multiscale model presented here is useful in the formulation design for controlled surface hydrophobicity of PDMS surfaces, and it facilitates the applications of PDMS in various aqueous systems.

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Molecular dynamics simulations of wetting behavior of water droplets on polytetrafluorethylene surfaces

Cited by 50 publications

References 50 publications

Local pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit pore obtained by the perturbative method

Local pressure components and interfacial tensions of a liquid film in the vicinity of a solid surface with a nanometer-scale slit pore obtained by the perturbative method

Molecular Dynamics Simulation of Wetting Behavior: Contact Angle Dependency on Water Potential Models

Multiscale Modeling to Predict the Hydrophobicity of an Experimentally Designed Coating

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