Water molecular bridge undermines thermal insulation of Nano-porous silica aerogels

Yang, M.Y.; Sheng, Qiang; Hu, Zhang; Tang, G.H.

doi:10.1016/j.molliq.2021.118176

Cited by 23 publications

(5 citation statements)

References 48 publications

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“…Its corresponding snapshots of molecular dynamics are shown in Figures f–j. The number density of the inner water droplet is equal to that of the bulk water liquid (0.03 Å –3 ), which agrees well with the literature …”

Section: Interaction Validationsupporting

confidence: 91%

“…The number density of the inner water droplet is equal to that of the bulk water liquid (0.03 Å −3 ), which agrees well with the literature. 49 To quantitatively describe those interactions, their corresponding contact angle is measured. As shown in Figure 4a, based on its distributions of number density, the curve of the water droplet at the equilibrium state is obtained.…”

Section: ■ Interaction Validationmentioning

confidence: 99%

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Atomic-Level Insights into Hollow Silica-Based Materials for Drug Delivery: Effects of Wettability and Porosity

Song,

Dong,

Dong

et al. 2023

ACS Biomater. Sci. Eng.

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Experimental evidence has demonstrated that the drug carrier capacity can be significantly enhanced through the use of hollow silica particles. Nevertheless, the effects of varying functional drug carrier surfaces and porous structures remain ambiguous. This study employs molecular dynamics simulations to examine the effects of varying the surface wettability, pore size, and flow velocity on the transfer process. The different levels of wettability of the silica surface with the coarse-grained water model is illustrated by adjusted interaction parameters. The effect of wettability is investigated. With weak interactions, the flow molecules form a nanodroplet to transfer through the porous structure. A strong interaction will lead to molecules flowing as a liquid film to transfer through the structure. Interestingly, the “contradiction effect” is observed when the flow molecules fail to penetrate the porous structure with weak interactions, during which surface tension dominates their flow behavior. Moreover, different porous structures are considered. The flow behaviors are divided into three processes: (1) fast flowing, (2) transient point, and (3) penetration flowing. Furthermore, the concept of surface molecules is defined to quantitatively measure the effect of porosity. A recommended contact angle is proposed. The results will pave the way for more carrier structures in medical engineering.

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Section: Interaction Validationsupporting

confidence: 91%

Section: ■ Interaction Validationmentioning

confidence: 99%

Atomic-Level Insights into Hollow Silica-Based Materials for Drug Delivery: Effects of Wettability and Porosity

Song,

Dong,

Dong

et al. 2023

ACS Biomater. Sci. Eng.

View full text Add to dashboard Cite

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“…In the present work, an amorphous silica plate is prepared by the “melt–quench method” , and the interactions in silica are modeled by a modified Tersoff potential . More details can be found in our previous work …”

Section: Methodsmentioning

confidence: 99%

“…38 More details can be found in our previous work. 39 For the nitrogen−silica system, nitrogen based on a coarse grain model is employed to represent gas molecules, where the force between gas molecules is modeled by the Lennard−Jones potential 40 φ(r) = 4ε[(σ/r) 12 − (σ/r) 6 ], where r is the intermolecular separation, σ is the length scale, and ε is the energy scale. The function is truncated at the cutoff radius r c = 4.0σ, beyond which molecular interactions are neglected.…”

Section: ■ Introductionmentioning

confidence: 99%

How Gas–Solid Interaction Matters in Graphene-Doped Silica Aerogels

et al. 2022

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It was interesting to experimentally find that the thermal insulation of silica aerogels was improved by doping graphene sheets with high heat conductivity. The underlying mechanism is investigated in the present work from the perspective of gas−solid interaction using a comprehensive analysis of molecular dynamics (MD) simulations, theoretical modeling, and experimental data. The MD-modeled small pores are demonstrated to effectively represent big pores in silica aerogels because of similar heat conduction physics, because it is found that adsorption does not contribute to gas heat conduction. Meanwhile, based on the experimentally measured density, the porous structures are schematically re-engineered using molecular modeling for the first time. The evaluated pore size distributions numerically present a consistency with available experimental data. Inspired by the visualization of the 3D pore structure, we proposed a graphene/silica/nitrogen model to evaluate the role of graphene in heat conduction: it can not only reduce effective gas collision (impede heat transport) but also enhance the gas−solid coupling effect. The former is dominant because of the high porosity, leading to an improvement in thermal insulation. The competition between them can be the reason for the "trade-off" phenomenon in the graphene doping effect in the available experiment.

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“… 22 Additionally, they investigated the effect of water molecules on the TC of SA, discovering that the adsorption of water molecules can fill molecular-level defects, reducing phonon scattering and thus enhancing TC. 23 However, despite the significant progress made by the MD method in revealing the TC mechanisms of SA, current research still has limitations. For example, intuitive characterization methods for the pore structure in aerogels are not yet mature, and the specific impact of porosity on thermal conduction mechanisms is not fully understood.…”

Section: Introductionmentioning

confidence: 99%