ACS Omega
·
2019
·
IF 2.584
Hao Xu,Chao Chang,Nan Yi,Peng Tao,Chengyi Song,Jianbo Wu,Tao Deng,Wen Shang
This paper studied the coalescence, spreading, and rebound of two droplets with different temperatures on a superhydrophobic surface. When the temperature of the impacting droplet was the same as that of the stationary droplet, there was a large deformation of both droplets before the coalescence and the energy dissipation was also large. The coalescence happened at the time close to the maximum spreading. When the temperature of the impacting droplet increased, the deformation of both droplets became smaller before the coalescence and the coalescence happened at or even before the droplets started to spread. The energy dissipation and loss in the later situation is less than those in the previous case. The rebounding characteristics of the merged droplets were also found to be dependent on the temperature. There is an optimum temperature at which the merged droplets can rebound for more times due to the balance of energy loss and also the interaction of the merged droplets with the underlying superhydrophobic substrate. These findings may help further the fundamental understanding of droplet collision on a superhydrophobic surfaces and also offer an alternative strategy to remove droplets from the underlying surfaces for different industrial applications, including condensation heat transfer in steam power plants and phase-change-based thermal management systems.
研究领域:
物理学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CANADIAN JOURNAL OF CHEMICAL ENGINEERING
·
2022
·Vol. 101
·期 7
·4170-4183
·
IF 2.5
Feng Rong,Limin He,Yuling Lü,Ce Wang,Shipeng Wang
Microscopic adhesion of oil droplets is a hot research topic within multiphase flow systems in the petrochemical field in recent years, and it is also the key to revealing the mechanism of oil droplet–wall interaction. In this paper, a high-speed camera was used to capture the dynamic process of oil droplets impacting stainless steel, polyethylene, brass, and other materials in water, deeply analyze the influence mechanism of material wettability, droplet size, and inclination on adhesion behaviour in this process, and draw the Re~ θ eq phase diagram. The experimental results show that properly enhancing the lipophilicity of the material can prolong the drainage time and effectively inhibit adhesion. Too much lipophilicity can dramatically shorten the drainage time instead, which easily leads to the rapid adhesion of oil droplets. An increase in droplet size can also prolong the drainage time; at Re ≥46.31, the excessive initial kinetic energy is consumed in the form of oil droplet rebound, which is not conducive to adhesion, and the more lipophilic the material is, the more significant the rebound effect. In addition, although an increase in the inclination can inhibit oil droplet bounce off, it also decreases the wall restraint to oil droplets, resulting in lateral and normal displacements, which greatly increases the drainage time. The findings can facilitate the understanding of oil droplet–wall interaction and provide a scientific basis for the design and development of efficient separation equipment and the optimization of the low-temperature gathering and transportation of high water-bearing crude oil.
研究领域:
石油工程
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表面科学
✓ 已验证
产品关联
DOI
高影响因子
LANGMUIR
·
2023
·
IF 3.9
Hailong Liu,Nuo Zheng,Jiaqi Chen,Ding Yang,Junfeng Wang
The control of a droplet bouncing on a substrate is of great importance not only in academic research but also in practical applications. In this work, we focus on a particular type of non-Newtonian fluid known as shear-thinning fluid. The rebound behaviors of shear-thinning fluid droplets impinging on a hydrophobic surface (equilibrium contact angle θeq ≈ 108°and contact angle hysteresis Δθ ≈ 20°) have been studied experimentally and numerically. The impact processes of Newtonian fluid droplets with various viscosities and non-Newtonian fluid droplets with dilute xanthan gum solutions were recorded by a high-speed imaging system under a range of Weber numbers (We) from 12 to 208. A numerical model of the droplet impact on the solid substrate was also constructed using a finite element scheme with the phase field method (PFM). The experimental results show that unlike the Newtonian fluid droplets where either partial rebound or deposition occurs, complete rebound behavior was observed for non-Newtonian fluid droplets under a certain range of We. Moreover, the minimum value of We required for complete rebound increases with xanthan concentration. The numerical simulations indicate that the shear-thinning property significantly affects the rebound behavior of the droplets. As the amount of xanthan increases, the high shear rate regions shift to the bottom of the droplet and the receding of the contact line accelerates. Once the high shear rate region appears only near the contact line, the droplet tends to fully rebound even on a hydrophobic surface. Through the impact maps of various droplets, we found that the maximum dimensionless height Hmax* of the droplet increases almost linearly with We as Hmax* ∼ αWe. In addition, a critical value Hmax, c* for the distinction between deposition and rebound for droplets on the hydrophobic surface has been theoretically derived. The prediction of the model shows good consistency with the experimental results.
研究领域:
流体力学
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材料科学
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界面科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF MATERIALS RESEARCH
·
2023
·Vol. 38
·期 9
·2339-2348
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IF 2.7
Zhou Jiajie,Li Longyang,Zhu Lijing,Zeng Zhixiang,Zhang Jinwei,Lin Cunguo
When the impact force of the droplets is low (the Weber number is low), the influence of the solid surface and the lubricating liquid cannot be ignored. Here, slippery liquid-infused surfaces were prepared by hydrochloric acid etching and low surface energy triethoxy-1H,1H,2H,2H-tridecafluoro-n-octylsilane modification on Al sheets, then infiltrated with different lubricating liquids. The bounce behavior of droplets is studied under the condition of controlling the Weber number is 19. The results show that the lubricating liquids can be locked when the roughness is sufficient. The adhesion of a slippery liquid-infused surface is related to the surface tension and viscosity, which is lower, and it is more beneficial to droplet bounce. But lubricating fluids with too low viscosity are more likely to be lost from the microstructure after being struck by droplets. It is significant for the application of slippery liquid-infused surfaces in low impact. Graphical Abstract
研究领域:
材料科学
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
ACS Sustainable Chemistry & Engineering
·
2024
·
IF 7.1
Yue Wang,Ridan Song,Haiqi Huang,Zhenping Bao,Yuxia Gao,Yanling Wu,Songhao Zhang,Rui Liu,Chenhui Zhang,Fengpei Du
How to restrain the bounce behavior of droplets on hydrophobic surfaces is a problem in daily life, especially during pesticide spraying. Adding polymer is a constructive strategy to enhance the ability of pesticide deposition on plant leaves, but it lacks guidance about the relationship between molecular structure and regulation capacity. This study selected poly(vinyl alcohol) (PVA) with different degrees of alcoholysis and polymerization to explore physicochemical properties in different dimensions affecting the bounce behavior. The results revealed that PVA-1788 had the best regulatory ability according to suitable phase viscosity, good surface activity, high adhesion force, and tensile viscosity. Based on statistical analysis, breaking distance at the solid–gas–liquid three-phase line is quantitative sustainability metrics to promote droplet adhesion. Namely, the solution containing PVA-1788 were embedded in the micronano structures on the hydrophobic surfaces to form claw structures and then produced the pinning effect for enhancing energy consumption so as to inhibit the droplet retraction. This mechanism was verified by SEM and fluorescence microscopy, and the higher the release height, the faster the initial rate, resulting in the significant pinning effect, because of obvious bordered deposition and permeation. This study provides the mechanism into guiding polymer adjuvants added in pesticides in view of quantitative sustainability metrics, which can lead to economic and environmental benefits in the future.
研究领域:
材料科学
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农业科学
·
表面化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Zhenming Chu,Weicheng Jiao,Yifan Huang,Liuyang Chen,Yongting Zheng,Rongguo Wang,Xiaodong He
The directional rebound control of droplets is of great significance in many industrial applications, such as anti-icing, self-cleaning and microfluidics devices. Various strategies of droplets directional transport have been studied at room temperature and high temperature. However, it is still a challenge to control the rebound direction of droplets without external forces at low temperature and condensation conditions, where the droplets transit to Wenzel state. Herein, two kinds of graphene-based wrinkled superhydrophobic films with regular high-low structures (RSGF) and irregular spiral structures (ISGF) are prepared. The droplets on the films are still in the Cassie state by adjusting the size of the microstructure at low temperature. More importantly, the experimental and numerical simulation results reveal that the regularity of wrinkled structures can be used to adjust the distribution of viscous forces between film and droplets, which can control the direction of droplets rebound force. On the RSGF, the impacting droplets can retract symmetrically and rebound along the vertical direction; while on the ISGF, the droplets retract asymmetrically due to the irregular spiral microstructure and the rebound direction is shifted in the fixed direction.
研究领域:
材料科学
·
流体力学
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2020
·
IF 8.758
Yue Ma,Yuxia Gao,Kefei Zhao,Hao Zhang,Zilu Li,Fengpei Du,Jun Hu
Despite small-molecule surfactants and polymers being widely used as pesticide adjuvants to inhibit droplet bouncing and splashing, they still have intrinsic drawbacks either in the easy wind drift and evaporation, the unfavorable wettability, or the usage of nonrenewable resources. In this paper, we found that upon droplet impacting, 1D nanofibers assembled from natural glycyrrhizic acid (GL) could pin on the rough hydrophobic surface and delay the retraction rate of droplets effectively. Using GL as a tank-mixed adjuvant, the efficiency of glyphosate to control the weed growth was improved significantly in the field experiment, which addressed the dilemmas of current adjuvants elegantly. Our work not only provides a constructive way to overcome droplet bouncing but also prompted us to verify in future if all 1D nanofibers assembled from different small molecules can display similar control efficiencies.
研究领域:
植物科学
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农业科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Advanced Materials Interfaces
·
2021
·Vol. 9
·期 1
·2101515
·
IF 6.147
Haoran Li,Xiaolong Chen,Wenpeng Hong,Yan Li,Boyu Li
Natural freezing at a low temperature poses fatal threats to aircraft, cables, and plants. Accelerating the rebound of the impacting droplet is an important approach to reduce ice accretion on the solid surface. Herein, a superhydrophobic copper myristate surface with a static contact angle of 158° is prepared to study the dynamic behaviors of the impacting droplet on the inclined surface. For the first time, the sudden contraction of the impacting droplet, especially in the cases at a high Weber number, is reported. With the increase of the Weber number, after reaching the maximum wetting diameter, the contraction process changes from direct contraction to sliding at first and then contracting while maintaining the maximum wetting diameter. Further investigations confirm that the sudden contraction of the trailing edge is the underlying mechanism for accelerating the droplet rebound. This discovery provides new insight and explanation for the dynamic evolution of impacting droplets on the inclined superhydrophobic surface.
研究领域:
材料科学
·
流体力学
✓ 已验证
产品关联
DOI
高影响因子
Nature Communications
·
2024
·Vol. 15
·期 1
·1-11
·
IF 14.7
Li Yanhong,Zhao Wenchang,Zhou Ying,Tang Shuxian,Wang Shiyu,Zheng Yutong,Wang Zuankai,Zhu Pingan
The rebound of liquid droplets on solid surfaces exhibits behavior reminiscent of elastic spheres, albeit with distinct contact dynamics. While the rapid detachment of droplets from surfaces holds significant relevance for various applications, previous endeavors relying on engineered surfaces can only reduce the contact time to several milliseconds, primarily due to capillary effects dominating droplet bounce. Here, we present ultrafast rebound by designing heterogeneous core-shell droplets encapsulating a particle (DEP), which achieves an unprecedentedly short contact time of 0.3 ms and 0.05 ms with polydimethylsiloxane and glass particles, respectively. This remarkable contact-time reduction is universally applicable to diverse systems, including both water and oil droplets, elastic and rigid particles, super-repellent and superlyophilic surfaces, and is effective across a wide range of impact velocities. Beyond exhibiting liquid-like dynamics, DEP manifests solid-like behavior owing to asynchronized motions between the particle and the droplet, which effectively breaks down the dominance of capillarity. With systematic experimental and analytical studies, we delineate contact times in three bouncing regimes and identify critical conditions governing regime transitions. DEP amalgamates the bouncing dynamics of both solids and liquids, offering a robust and versatile strategy for tailoring contact time to suit diverse applications involving solid-liquid composite systems.
研究领域:
流体力学
·
材料科学
·
界面化学
✓ 已验证
DOI
高影响因子
LANGMUIR
·
2025
·
IF 3.9
Yue Zhang,Ao Gong,Tao Wang,Shuai Zhang,Ying Nie,Xun Sun
Manipulation of directional bouncing behavior of liquid droplets after impacting solid surfaces is highly significant for biological, agricultural, engineering, and industrial applications. Here, we prepared a surface with a chemical gradient on a Ti-6Al-4V substrate, on which directional multiple bouncing of droplets and long-range movement has been achieved. The wetting gradient of the vapor-deposited surface reached 2.5° mm–1 by finely controlling the distribution of low surface energy functional groups. Droplet adhesion force analysis was carried out to visualize the variation of surface wettability. On this surface with inhomogeneous wettability, the droplet repeated the impacting and rebounding 8 times along the direction of the chemical gradient, displaying an interesting phenomenon of “droplet trampoline”. The maximal rebound height and the horizontal jumping distance reached 8.36 and 10.19 mm, respectively. Additionally, the underlying mechanism behind this consecutive bouncing behavior of droplets was thoroughly elucidated from energy and force perspectives. This research is anticipated to advance the understanding of directional continuous bounce behavior of a droplet and provide a promising strategy to delicately manipulate the movement of droplets.
研究领域:
材料科学
·
表面工程
·
流体力学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PEST MANAGEMENT SCIENCE
·
2025
·
IF 3.8
Feng-yu Li,Meng Yu,Yu Fang,Ying-jian Ma,Yin-min Wang,Shou-he Pan,Lin Mu,Xin-yu Guo,Sen Pang,Yong Xu,Rui Zhao,Xue-min Wu
Background Droplet rebound on superhydrophobic leaves during pesticide application significantly increases pesticide waste and decreases application efficiency. An appropriate surfactant is crucial for suppressing droplet rebound and enhancing wetting and spreading on leaf surfaces. Results The rebound, wetting and spreading behaviors of cetyltrimethylammonium bromide (C n TAB) series of surfactants with varying different carbon chain lengths ( n = 6–16) were evaluated on peanut leaves. Aqueous solutions of C 6 TAB–C 16 TAB were prepared, their physicochemical properties were assessed. The surface properties of peanut leaves and droplet impact, wetting, and spreading behaviors were also tested. Conclusion At equivalent concentrations, shorter-chain surfactant molecules were less effective at forming likely micellar aggregates that suppress droplet rebound. However, as chain length increased, the wetting and spreading rate of surfactant molecules improved, resulting in reverse wetting and suppressing bouncing. Furthermore, the impact of leaf micro/nanostructures and charge properties on the wetting behavior of different surfactant droplets was elucidated, revealing factors underlying the enhanced retention quantity and poor wetting and spreading of the C n TAB series. These findings may aid in reducing pesticide waste and provide multidimensional support for the precise control of droplet behavior in different scenarios and during C n TAB application. These findings hold substantial value for future agricultural spraying applications, especially for unmanned aerial vehicle plant protection. © 2025 Society of Chemical Industry.
研究领域:
植物科学
·
农业化学
·
农药应用
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Surfaces and Interfaces
·
2023
·
IF 6.2
Rui Zhao,Meng Yu,Zhe Sun,Shou-he Pan,Yin-min Wang,Ying-jian Ma,Xin-yu Guo,Yong Xu,Xue-min Wu
Regulation of the droplet impact and wetting behavior of hydrophobic surfaces is a difficult problem to solve. The addition of surfactants is commonly used to improve droplet retention by modifying interfacial properties . The effect of the surfactant structure on the regulation of droplet rebound and wetting behavior needs further research. In this study, the physicochemical properties and regulation of droplet behavior for nonionic surfactants with different hydrophilic chain lengths were investigated. The results indicate that with an increasing hydrophilic chain (Epoxyethane (EO) numbers) length, Isodecyl polyoxyethylene ether (XL) surfactant solutions could better regulate the droplet impact behavior on hydrophobic surfaces and better suppress droplet rebound. This mainly attributed to a faster diffusion of surfactant molecules to newly formed interfaces, thus leading to better wetting reversal and deposition of substrates. Additionally, it was found that with the reduction of the hydrophilic chain length, XL surfactant solutions could better regulate droplet wetting, mainly attributed to its critical micelle concentration and surface tension, creating greater Marangoni forces during spreading and leading to faster spreading rates and larger spreading areas. The results from this study promote understanding of the mechanism for regulation of impact behavior and surfactant solution wetting on hydrophobic surfaces by regulating the EO chain length. This provides an effective strategy in regulating droplet deposition on hydrophobic surfaces and provides the basic data or guidance for the use of nonionic surfactants as tank-mixing adjuvants in unmanned aerial vehicle plant protection.
研究领域:
化学
·
农业科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）