1
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Ma C, Chen Y, Chu J. Time-Dependent Pinning of Nanoblisters Confined by Two-Dimensional Sheets. Part 2: Contact Line Pinning. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:709-716. [PMID: 36596242 DOI: 10.1021/acs.langmuir.2c03318] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Pinning of droplets on solids is an omnipresent wetting phenomenon that attracts intense research interest. Unlike in classical wetting, pinning effects in a novel wetting problem where droplets are confined onto the substrates by elastic films have hardly been investigated. Here, following our study in an accompanying paper (part 1) on the static mechanics of nanoscale blisters confined between a two-dimensional elastic sheet and its substrate, we investigate in this part the pinning behaviors of such blisters by using atomic force microscopy. The blisters' lateral retention forces are shown to scale almost linearly with their contact lines and to increase until saturation upon increasing their resting times. Our analysis reveals a mechanism of microdeformation of the substrate at the contact line. The creep of the microdeformation is found to cause the time-dependent pinning, which is evidenced by residual fine ridge structures left by blisters after their spread after long resting times.
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2
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Noël O, Mazeran PE, Stanković I. Nature of Dynamic Friction in a Humid Hydrophobic Nanocontact. ACS NANO 2022; 16:10768-10774. [PMID: 35731935 DOI: 10.1021/acsnano.2c02665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
The physics of dynamic friction on water molecule contaminated surfaces is still poorly understood. In line with the growing interest in hydrophobic contact for industrial applications, this paper focuses on friction mechanisms in such interfaces. As a commonly used material, contact with graphite is considered in a twin-fold approach based on experimental investigations using the circular mode atomic force microscopy technique combined with molecular dynamic simulations. We demonstrate that an intuitive paradigm, which asserts that water molecules are squeezed out of a hydrophobic contact, should be refined. As a consequence, we introduce a mechanism considering a droplet produced within the sliding nanocontact by the accumulation of water adsorbed on the substrate. Then we show that a full slip regime of the droplet sliding on the hydrophobic substrate explains the experimental tribological behavior.
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Affiliation(s)
- Olivier Noël
- IMMM, UMR CNRS 6283, Le Mans Université, Avenue O. Messiaen, 72085 Cedex 09, Le Mans, France
| | - Pierre-Emmanuel Mazeran
- Sorbonne Universités, Université de Technologie de Compiègne, Laboratoire Roberval, FRE UTC-CNRS 2012, Centre de Recherche de Royallieu, CS 60319, 60203, Compiègne Cedex, France
| | - Igor Stanković
- Scientific Computing Laboratory, Center for the Study of Complex Systems, Institute of Physics Belgrade, University of Belgrade, Pregrevica 118, 11080 Belgrade, Serbia
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3
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Jena AK, Bhimavarapu YVR, Tang S, Liu J, Das R, Gulec S, Vinod A, Yao CW, Cai T, Tadmor R. Stages That Lead to Drop Depinning and Onset of Motion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:92-99. [PMID: 34939810 DOI: 10.1021/acs.langmuir.1c02091] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
In this paper, we consider drops that are subjected to a gradually increasing lateral force and follow the stages of the motion of the drops. We show that the first time a drop slides as a whole is when the receding edge of the drop is pulled by the advancing edge (the advancing edge drags the receding edge). The generality of this phenomenon includes sessile and pendant drops and spans over various chemically and topographically different cases. Because this observation is true for both pendant and sessile cases, we exclude hydrostatic pressure as its reason. Instead, we explain it in terms of the wetting adaptation and interfacial modulus, that is, the difference in the energies of the solid interface at the advancing and receding edges. At the receding edge, a slight motion exposes to the air a recently wetted solid surface whose molecules had reoriented to the liquid and will take time to reorient back to the air. This results in a high surface energy at the solid-air interface which pulls on the triple line, that is, inhibits the motion of the receding edge. On the other hand, at the advancing edge, a slight advancement does not change the nature of the solid interfacial molecules outside the drop, and the advancing side's sliding can continue. Moreover, the solid molecules under the drop at the advancing edge take time to reorient, and hence, their configuration is not yet adapted for the liquid and therefore not adapted for retention of the advancing edge. Therefore, in sliding-drop experiments, the advancing edge moves before the receding one, typically a few times before the receding edge moves. For the same reason, the last motion of the receding edge usually happens as a result of the advancing edge pulling on it.
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Affiliation(s)
- Akash K Jena
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Yagna Valkya Reddy Bhimavarapu
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Sirui Tang
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Jie Liu
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Ratul Das
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Semih Gulec
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Appu Vinod
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Chun-Wei Yao
- Department of Mechanical Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Tianxing Cai
- Dan F. Smith Department of Chemical & Biomolecular Engineering, Lamar University, P.O. Box 10053, Beaumont Texas 77710, United States
| | - Rafael Tadmor
- Department of Mechanical Engineering, Ben Gurion University, Beer Sheva 84105, Israel
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4
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Ding W, Dorao CA, Fernandino M. Improving superamphiphobicity by mimicking tree-branch topography. J Colloid Interface Sci 2021; 611:118-128. [PMID: 34933190 DOI: 10.1016/j.jcis.2021.12.056] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/17/2022]
Abstract
when a droplet impacts on a superhydrophobic structured surface below a certain impact velocity, the droplet can bounce off completely from the surface. However, above such velocity a fraction of the droplet will pin on the surface. Surfaces capable of repelling water droplets are ubiquitous in nature or have been artificially fabricated. However, as the surface tension of the liquid is reduced, the capability of the surface to remain non-wetting gets hindered. Despite progress in previous research, the understanding and development of superamphiphobic surface to impacting low surface tension droplets remains elusive. It is proposed that multi-layer re-entrant like roughness can further enhance the anti-wetting properties also for low surface tension fluids. In this work, we produce patterned conical micro-structures with lateral nano-sized roughness. Furthermore, the droplet impact experiments are conducted on various surfaces with variable surface tensions (27 mN/m - 72 mN/m) by using droplets with different Weber numbers (2-170). We show that conical microstructures with lateral roughness mimicking tree-branches provides a surface topology capable of absorbing the force exerted by the droplet during the impact which prevents the droplet from pinning on the surface at higher impact velocity even for low surface tension droplets. Our study has significance for understanding the liquid interaction mechanism with the surface during the impact process and for the associated surface design considerations.
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Affiliation(s)
- Wenwu Ding
- Department of Energy and Process Engineering. Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Carlos Alberto Dorao
- Department of Energy and Process Engineering. Norwegian University of Science and Technology, Trondheim 7491, Norway
| | - Maria Fernandino
- Department of Energy and Process Engineering. Norwegian University of Science and Technology, Trondheim 7491, Norway.
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5
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Tadmor R. Open Problems in Wetting Phenomena: Pinning Retention Forces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:6357-6372. [PMID: 34008988 DOI: 10.1021/acs.langmuir.0c02768] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We review existing explanations for drop pinning and the origin of the force required to initiate the sliding of a drop on a solid surface (depinning). Theories that describe these phenomena include de Gennes', Marmur's, Furmidge's, the related Furmidge-Extrand's, and Tadmor's theory. These theories are all well cited but generally do not address each other, and usually papers that cite one of them ignore the others. Here, we discuss the advantages and disadvantages of these theories and their applicability to different experimental systems. Thus, we link different experimental systems to the theories that describe them best. We describe the force laws that can be deduced should these theories be united and the major open problems that remain. We describe a physical meaning that can be extracted from retention force measurements, specifically, the interfacial modulus that describes the tendency of a solid to conform to the liquid. This has implications for various wetting phenomena such as adhesion robustness, drug penetration into biological tissues, and solid robustness/resilience versus solid degradation over time as a result of its contact with a liquid.
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Affiliation(s)
- Rafael Tadmor
- Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105, Israel
- Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont Texas 77710, United States
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6
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Kordijazi A, Behera S, Patel D, Rohatgi P, Nosonovsky M. Predictive Analysis of Wettability of Al-Si Based Multiphase Alloys and Aluminum Matrix Composites by Machine Learning and Physical Modeling. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3766-3777. [PMID: 33730496 DOI: 10.1021/acs.langmuir.1c00358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Wetting of multiphase alloys and their composites depends on multiple parameters, and these relationships are difficult to predict from first principles only. We study correlations between the composition, surface finish, and microstructure of Al-Si alloys (Si content 7-50%) and Al metal matrix composites (MMCs) with graphite (Gr), NiAl3, and SiC and the water contact angle (CA) experimentally, theoretically, and with machine learning (ML) techniques. Their surface properties were modified by mechanical abrasion, etching, and addition of alloying elements. An ML approach was developed to investigate correlations between the predictor variables (properties of the materials) and the CA. Theoretical models of wetting of rough surfaces (Wenzel, Cassie-Baxter, and their modifications) do not fully capture the CA, while ML models follow the experimental values. A full factorial design is utilized with combinations of all levels of the predictor factors (grit size, silicon percentage, droplet size, elapsed time, etching, reinforcing particles). To map the predictor variables to the response variables, 409 experimental data points were applied to train and test various supervised ML models, namely, regression, artificial neural network (ANN), chi-square automatic interaction detection (CHAID), extreme gradient boosting (XGBoost), and random forest. The correlations between the most significant factors and CA are explored through visualization techniques. The most accurately trained model shows a strong positive linear correlation (r > 0.9) between predicted and observed CA values in the test set, indicating the robustness of the model. The experimental measurements and artificial intelligence results demonstrate that CA increases following mechanically abrading the surface, etching, and adding Gr to the surface. The ML methods are promising to predict wetting properties and to provide a deeper understanding of the physical phenomena associated with the wettability of metallic alloys and their metal matrix composites.
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Affiliation(s)
- Amir Kordijazi
- Department of Industrial and Manufacturing Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
- Department of Material Science and Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Swaroop Behera
- Department of Material Science and Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Dhrumil Patel
- Department of Material Science and Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Pradeep Rohatgi
- Department of Material Science and Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
| | - Michael Nosonovsky
- Department of Mechanical Engineering, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, United States
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7
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Tadmor R, Tang S, Yao CW, Gulec S, Yadav S. Comment on "Comparison of the Lateral Retention Forces on Sessile, Pendant, and Inverted Sessile Drops". LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:475-476. [PMID: 31838847 DOI: 10.1021/acs.langmuir.9b02660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Tadmor et al.'s 2009 PRL article shows experiments of pendant drops with ∼30% higher retention forces than their sessile analogues. A recent article (de la Madrid, R. et al. Langmuir 2019, 35, 2871) seemingly explains this result theoretically using a drastically different experimental system that shows a ∼3% higher force that exceeds the scatter in three out of four data points. The differences between the two experimental systems might have allowed the two theories to coexist, but Tadmor's theory, which can explain both, allows an understanding of the solid-liquid interaction, which the newer theory lacks.
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Affiliation(s)
- Rafael Tadmor
- Department of Mechanical Engineering , Ben Gurion University , Beer Sheva , Israel
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8
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Tang S, Bhimavarapu Y, Gulec S, Das R, Liu J, N Guessan H, Whitehead T, Yao CW, Tadmor R. Droplets Sliding down a Vertical Surface under Increasing Horizontal Forces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8191-8198. [PMID: 30990708 DOI: 10.1021/acs.langmuir.8b04157] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We have investigated the retention forces of liquid drops on rotating, vertical surfaces. We considered two scenarios: in one, a horizontal, centrifugal force pushes the drop toward the surface (?pushed drop? case), and in the other, a horizontal, centrifugal force pulls the drop away from the surface (?pulled drop? case). Both drops slide down as the centrifugal force increases, although one expects that the pushed drop should remain stuck to the surface. Even more surprising, when the centrifugal force is low, the pushed drop moves faster than the pulled drop, but when the centrifugal force is high, the pushed drop moves much slower than the pulled drop. We explain these results in terms of interfacial modulus between the drop and the surface.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Rafael Tadmor
- Department of Mechanical Engineering , Ben Gurion University , Beer Sheva , Israel
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9
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Papadopoulou E, Megaridis CM, Walther JH, Koumoutsakos P. Ultrafast Propulsion of Water Nanodroplets on Patterned Graphene. ACS NANO 2019; 13:5465-5472. [PMID: 31025854 DOI: 10.1021/acsnano.9b00252] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The directed transport of liquids at the nanoscale is of great importance for nanotechnology applications ranging from water filtration to the cooling of electronics and precision medicine. Here we demonstrate such unidirectional, pumpless transport of water nanodroplets on graphene sheets patterned with hydrophilic/phobic areas inspired by natural systems. We find that spatially varying patterning of the graphene surfaces can lead to water transport at ultrafast velocities, far exceeding macroscale estimates. We perform extensive molecular dynamics simulations to show that such high transport velocities ( O(102 m/s)) are due to differences of the advancing and receding contact angles of the moving droplet. This contact angle hysteresis and the ensuing transport depend on the surface pattern and the droplet size. We present a scaling law for the driving capillary and resisting friction forces on the water droplet and use it to predict nanodroplet trajectories on a wedge-patterned graphene sheet. The present results demonstrate that graphene with spatially variable wettability is a potent material for fast and precise transport of nanodroplets with significant potential for directed nanoscale liquid transport and precision drug delivery.
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Affiliation(s)
- Ermioni Papadopoulou
- Computational Science and Engineering Laboratory , ETH Zürich , Zürich CH-8092 , Switzerland
| | - Constantine M Megaridis
- Department of Mechanical and Industrial Engineering , University of Illinois at Chicago , Chicago , Illinois 60607 , United States
| | - Jens H Walther
- Computational Science and Engineering Laboratory , ETH Zürich , Zürich CH-8092 , Switzerland
- Department of Mechanical Engineering , Technical University of Denmark , 2800 Kongens Lyngby , Denmark
| | - Petros Koumoutsakos
- Computational Science and Engineering Laboratory , ETH Zürich , Zürich CH-8092 , Switzerland
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10
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Gulec S, Yadav S, Das R, Bhave V, Tadmor R. The Influence of Gravity on Contact Angle and Circumference of Sessile and Pendant Drops has a Crucial Historic Aspect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:5435-5441. [PMID: 30839217 DOI: 10.1021/acs.langmuir.8b03861] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Normally, pendant drops adapt contact angles that are closer to 90° than their sessile analogues. This is due to the drop's weight that pulls the pendant drop and straightens its contact angles. In this paper, we show a case in which the opposite happens: sessile drops that adapt contact angles that are closer to 90° than their pendant analogues. To achieve these peculiar states, one needs to increase the effective gravity on the drops and then relax it again to 1 g. Apparently, this and other phenomena depend not only on the direction of the gravitational force but also on the drop's history. We show that the drop's contact angle (and resultant area) is affected by two types of histories: short-term history and long-term history. For example, if we gradually increase the effective gravity on the drop, decrease it back to 1 g, and then repeat this cycle again and again, we see that the first cycle is drastically different, whereas other cycles approach a plateau in their behavior. In addition to drop's history, we explain these observations in terms of volume conservation, drop contact area, and pinning effect. This study may be generalized for other body forces such as electrical and magnetic or accelerating systems.
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Affiliation(s)
- Semih Gulec
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Sakshi Yadav
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Ratul Das
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Vaibhav Bhave
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Rafael Tadmor
- Dan F. Smith Department of Chemical Engineering , Lamar University , Beaumont , Texas 77710 , United States
- Department of Mechanical Engineering , Ben Gurion University , Beer Sheva 8410501 , Israel
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11
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Luo Z, Mehraeen S. Predictive Model to Probe the Impact of Gravity and Surface Tension on Rising Wetting Thin Films. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:4189-4196. [PMID: 30794419 DOI: 10.1021/acs.langmuir.8b03971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Utilizing kinetic Monte Carlo simulations, we developed a three-dimensional Ising lattice gas model to reveal the wetting mechanism of a liquid film rising along a vertical substrate. The model takes into account the impact of surface tension, gravity, and interaction energy between liquid particles and between liquid and substrate on the rise of the liquid film. We verify that in low gravitational acceleration regime, the growth of the liquid film follows the universal law of [Formula: see text]. As gravitational acceleration and surface tension vary, the simulation results show the detailed dynamics of the solid-liquid interface. Explicit analysis of the interface displacement and roughness under different gravitational accelerations and surface tensions is also presented.
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Affiliation(s)
- Zhen Luo
- Department of Chemical Engineering , University of Illinois at Chicago , 810 South Clinton Street , Chicago , Illinois 60607 , United States
| | - Shafigh Mehraeen
- Department of Chemical Engineering , University of Illinois at Chicago , 810 South Clinton Street , Chicago , Illinois 60607 , United States
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12
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Pan S, Guo R, Björnmalm M, Richardson JJ, Li L, Peng C, Bertleff-Zieschang N, Xu W, Jiang J, Caruso F. Coatings super-repellent to ultralow surface tension liquids. NATURE MATERIALS 2018; 17:1040-1047. [PMID: 30323333 DOI: 10.1038/s41563-018-0178-2] [Citation(s) in RCA: 142] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 08/29/2018] [Indexed: 06/08/2023]
Abstract
High-performance coatings that durably and fully repel liquids are of interest for fundamental research and practical applications. Such coatings should allow for droplet beading, roll off and bouncing, which is difficult to achieve for ultralow surface tension liquids. Here we report a bottom-up approach to prepare super-repellent coatings using a mixture of fluorosilanes and cyanoacrylate. On application to surfaces, the coatings assemble into thin films of locally multi-re-entrant hierarchical structures with very low surface energies. The resulting materials are super-repellent to solvents, acids and bases, polymer solutions and ultralow surface tension liquids, characterized by ultrahigh liquid contact angles (>150°) and negligible roll-off angles (~0°). Furthermore, the coatings are transparent, durable and demonstrate universal liquid bouncing, tailored responsiveness and anti-freezing properties, and are thus a promising alternative to existing synthetic super-repellent coatings.
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Affiliation(s)
- Shuaijun Pan
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China.
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia.
| | - Rui Guo
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Mattias Björnmalm
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia
- Department of Materials, Department of Bioengineering, and the Institute of Biomedical Engineering, Imperial College London, London, UK
| | - Joseph J Richardson
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Ling Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China
| | - Chang Peng
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China
- College of Science, Hunan Agricultural University, Changsha, China
| | - Nadja Bertleff-Zieschang
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia
| | - Weijian Xu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China.
| | - Jianhui Jiang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, China.
| | - Frank Caruso
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria, Australia.
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13
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Breki A, Nosonovsky M. Einstein's Viscosity Equation for Nanolubricated Friction. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:12968-12973. [PMID: 30296098 DOI: 10.1021/acs.langmuir.8b02861] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The generalized Einstein equation for the viscosity of a dispersion/suspension, μ = (1 + αfϕ)μ0, where μ0 is the liquid viscosity, ϕ is the solid volume fraction, and αf is a coefficient, is applied to the viscosity of a nanofluid lubricant. The coefficient of lubricated friction in the hydrodynamic regime is proportional to the viscosity of the lubricant. Therefore, an equation for the coefficient of friction with nanofluid lubrication can be formulated. We present such an equation and show its validity for common types of bearings (journal, rolling, and ball bearings). The equation, which may be viewed as one of nanofriction laws, is compared with experimental results for WS2 nanoparticle-enhanced oil lubrication, showing agreement within 7% accuracy.
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Affiliation(s)
- Alexander Breki
- Department of Machine Design , Peter the Great St. Petersburg Polytechnic University , 29 Polytechnicheskaya Street , St. Petersburg 195251 , Russia
| | - Michael Nosonovsky
- Mechanical Engineering , University of Wisconsin-Milwaukee , 3200 N. Cramer Street , Milwaukee , Wisconsin 53211 , United States
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14
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Abstract
When a three-phase contact line moves along a solid surface, the contact angle no longer corresponds to the static equilibrium angle but is larger when the liquid is advancing and smaller when the liquid is receding. The difference between the advancing and receding contact angles, i.e., the contact angle hysteresis, is of paramount importance in wetting and capillarity. For example, it determines the magnitude of the external force that is required to make a drop slide on a solid surface. Until now, fundamental origin of the contact angle hysteresis has been controversial. Here, this origin is revealed and a quantitative theory is derived. The theory is corroborated by the available experimental data for a large number of solid-liquid combinations. The theory is applied in modelling the contact angle hysteresis on a textured surface, and these results are also in quantitative agreement with the experimental data.
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Affiliation(s)
- Lasse Makkonen
- VTT Technical Research Centre of Finland, Espoo 02044 VTT, Finland
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15
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Yang Z, Bhowmick S, Sen FG, Banerji A, Alpas AT. Roles of sliding-induced defects and dissociated water molecules on low friction of graphene. Sci Rep 2018; 8:121. [PMID: 29317658 PMCID: PMC5760666 DOI: 10.1038/s41598-017-17971-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 12/04/2017] [Indexed: 11/09/2022] Open
Abstract
Sliding contact experiments and first-principles calculations were performed to elucidate the roles of structural defects and water dissociative adsorption process on the tribo-chemical mechanisms responsible for low friction of graphene. Sliding friction tests conducted in ambient air and under a dry N2 atmosphere showed that in both cases a high running-in coefficient of friction (COF) occurred initially but a low steady-state COF was reached only when the sliding was continued in air with moisture. Density functional theory (DFT) calculations indicated that the energy barrier (E b ) for dissociative adsorption of H2O was significantly lower in case of reconstructed graphene with a monovacancy compared to pristine graphene. Cross-sectional transmission electron microscopy of graphene transferred to the counterface revealed a partly amorphous structure incorporating damaged graphene layers with d-spacings larger than that of the original layers. DFT calculations on the reconstructed bilayer AB graphene systems revealed an increase of d-spacing due to the chemisorption of H, O, and OH at the vacancy sites and a reduction in the interlayer binding energy (E B ) between the bilayer graphene interfaces compared to pristine graphene. Thus, sliding induced defects facilitated dissociative adsorption of water molecules and reduced COF of graphene for sliding tests under ambient and humid environments but not under an inert atmosphere.
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Affiliation(s)
- Zaixiu Yang
- Engineering Materials Program, Mechanical, Automotive and Materials Engineering Department, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Sukanta Bhowmick
- Engineering Materials Program, Mechanical, Automotive and Materials Engineering Department, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Fatih G Sen
- Center for Nanoscale Materials, Argonne National Laboratory, Cass Ave, Lemont, IL, 60439, USA
| | - Anindya Banerji
- Engineering Materials Program, Mechanical, Automotive and Materials Engineering Department, University of Windsor, Windsor, Ontario, N9B 3P4, Canada
| | - Ahmet T Alpas
- Engineering Materials Program, Mechanical, Automotive and Materials Engineering Department, University of Windsor, Windsor, Ontario, N9B 3P4, Canada.
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16
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Relationship between contact angle and contact line radius for micro to atto [10−6 to 10−18] liter size oil droplets. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.10.134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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17
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Qiao S, Li S, Li Q, Li B, Liu K, Feng XQ. Friction of Droplets Sliding on Microstructured Superhydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13480-13489. [PMID: 29094600 DOI: 10.1021/acs.langmuir.7b03087] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Liquid transport is a fundamental process relevant to a wide range of applications, for example, heat transfer, anti-icing, self-cleaning, drag reduction, and microfluidic systems. For these applications, a deeper understanding of the sliding behavior of water droplets on solid surfaces is of particular importance. In this study, the frictional behavior of water droplets sliding on superhydrophobic surfaces decorated with micropillar arrays was studied using a nanotribometer. Our experiments show that surfaces with a higher solid area fraction generally exhibited larger friction, although friction might drop when the solid area fraction was close to unity. More interestingly, we found that the sliding friction of droplets was enhanced when the dimension of the microstructures increased, showing a distinct size effect. The nonmonotonic dependence of friction force on solid area fraction and the apparent size effect can be qualitatively explained by the evolution of two governing factors, that is, the true length of the contact line and the coordination degree of the depinning events. The mechanisms are expected to be generally applicable for other liquid transport processes involving the dynamic motion of a three-phase contact line, which may provide a new means of tuning liquid-transfer behavior through surface microstructures.
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Affiliation(s)
| | | | | | | | - Kesong Liu
- Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry and Environment, Beihang University , Beijing 100191, China
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18
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Chen SY, Kaufman Y, Schrader AM, Seo D, Lee DW, Page SH, Koenig PH, Isaacs S, Gizaw Y, Israelachvili JN. Contact Angle and Adhesion Dynamics and Hysteresis on Molecularly Smooth Chemically Homogeneous Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:10041-10050. [PMID: 28745509 DOI: 10.1021/acs.langmuir.7b02075] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Measuring truly equilibrium adhesion energies or contact angles to obtain the thermodynamic values is experimentally difficult because it requires loading/unloading or advancing/receding boundaries to be measured at rates that can be slower than 1 nm/s. We have measured advancing-receding contact angles and loading-unloading adhesion energies for various systems and geometries involving molecularly smooth and chemically homogeneous surfaces moving at different but steady velocities in both directions, ±V, focusing on the thermodynamic limit of ±V → 0. We have used the Bell Theory (1978) to derive expressions for the dynamic (velocity-dependent) adhesion energies and contact angles suitable for both (i) dynamic adhesion measurements using the classic Johnson-Kendall-Roberts (JKR, 1971) theory of "contact mechanics" and (ii) dynamic contact angle hysteresis measurements of both rolling droplets and syringe-controlled (sessile) droplets on various surfaces. We present our results for systems that exhibited both steady and varying velocities from V ≈ 10 mm/s to 1 nm/s, where in all cases but one, the advancing (V > 0) and receding (V < 0) adhesion energies and/or contact angles converged toward the same theoretical (thermodynamic) values as V → 0. Our equations for the dynamic contact angles are similar to the classic equations of Blake & Haynes (1969) and fitted the experimental adhesion data equally well over the range of velocities studied, although with somewhat different fitting parameters for the characteristic molecular length/dimension or area and characteristic bond formation/rupture lifetime or velocity. Our theoretical and experimental methods and results unify previous kinetic theories of adhesion and contact angle hysteresis and offer new experimental methods for testing kinetic models in the thermodynamic, quasi-static, limit. Our analyses are limited to kinetic effects only, and we conclude that hydrodynamic, i.e., viscous, and inertial effects do not play a role at the interfacial velocities of our experiments, i.e., V < (1-10) mm/s (for water and hexadecane, but for viscous polymers it may be different), consistent with previously reported studies.
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Affiliation(s)
- Szu-Ying Chen
- Department of Chemical Engineering, University of California at Santa Barbara (UCSB) , Santa Barbara, California 93106, United States
| | - Yair Kaufman
- Zuckerberg Institute for Water Research, The Jacob Blaustein Institutes for Desert Research, Ben Gurion University of the Negev , Sede Boqer Campus 84990, Midreshet Ben-Gurion, Israel
| | - Alex M Schrader
- Department of Chemical Engineering, University of California at Santa Barbara (UCSB) , Santa Barbara, California 93106, United States
| | - Dongjin Seo
- Department of Chemical Engineering, University of California at Santa Barbara (UCSB) , Santa Barbara, California 93106, United States
| | - Dong Woog Lee
- School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST) , UNIST-gil 50, Ulsan 689-798, Republic of Korea
| | - Steven H Page
- The Procter & Gamble Co. , Winton Hill Business Center, 6210 Center Hill Avenue, Cincinnati, Ohio 45224, United States
| | - Peter H Koenig
- The Procter & Gamble Co. , Beckett Ridge Technical Center, Union Centre Boulevard, West Chester Township, Ohio 45069, United States
| | - Sandra Isaacs
- The Procter & Gamble Co. , Winton Hill Business Center, 6210 Center Hill Avenue, Cincinnati, Ohio 45224, United States
| | - Yonas Gizaw
- The Procter & Gamble Co. , Winton Hill Business Center, 6210 Center Hill Avenue, Cincinnati, Ohio 45224, United States
| | - Jacob N Israelachvili
- Department of Chemical Engineering, University of California at Santa Barbara (UCSB) , Santa Barbara, California 93106, United States
- Materials Department, University of California at Santa Barbara (UCSB) , Santa Barbara, California 93106, United States
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19
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Evgenidis SP, Kalić K, Kostoglou M, Karapantsios TD. Kerberos : A three camera headed centrifugal/tilting device for studying wetting/dewetting under the influence of controlled body forces. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2016.07.079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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20
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Tadmor R, Das R, Gulec S, Liu J, E N'guessan H, Shah M, S Wasnik P, Yadav SB. Solid-Liquid Work of Adhesion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:3594-3600. [PMID: 28121158 DOI: 10.1021/acs.langmuir.6b04437] [Citation(s) in RCA: 93] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We establish a tool for direct measurements of the work needed to separate a liquid from a solid. This method mimics a pendant drop that is subjected to a gravitational force that is slowly increasing until the solid-liquid contact area starts to shrink spontaneously. The work of separation is then calculated in analogy to Tate's law. The values obtained for the work of separation are independent of drop size and are in agreement with Dupré's theory, showing that they are equal to the work of adhesion.
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Affiliation(s)
- Rafael Tadmor
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Ratul Das
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Semih Gulec
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Jie Liu
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Hartmann E N'guessan
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Meet Shah
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Priyanka S Wasnik
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
| | - Sakshi B Yadav
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont Texas 77710, United States
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21
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Terpiłowski K, Wiącek AE, Jurak M. Influence of nitrogen plasma treatment on the wettability of polyetheretherketone and deposited chitosan layers. ADVANCES IN POLYMER TECHNOLOGY 2017. [DOI: 10.1002/adv.21813] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Konrad Terpiłowski
- Department of Physical Chemistry - Interfacial Phenomena; Faculty of Chemistry; Maria Curie-Sklodowska University; Lublin Poland
| | - Agnieszka Ewa Wiącek
- Department of Physical Chemistry - Interfacial Phenomena; Faculty of Chemistry; Maria Curie-Sklodowska University; Lublin Poland
| | - Małgorzata Jurak
- Department of Physical Chemistry - Interfacial Phenomena; Faculty of Chemistry; Maria Curie-Sklodowska University; Lublin Poland
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22
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Zuo P, Liu J, Li S. The load-bearing ability of a particle raft under the transverse compression of a slender rod. SOFT MATTER 2017; 13:2315-2321. [PMID: 28230872 DOI: 10.1039/c6sm02752k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Liquid marbles and particle rafts are liquid interfaces covered with tiny particles, which are accompanied with many exotic behaviors. This study seeks to extend our understanding on the load-bearing ability of a particle raft under the transverse compression of a slender rod. At first, the interface morphologies of the particle raft and water are captured and compared with each other. Then the load-distance curves of the particle raft and water surface are measured using a self-developed device. For the particle raft, the hydrophobicity of the rod almost does not affect the interface morphology and the supporting load. To address the mechanism of this phenomenon, we perform the experiment and find that the surface tension of the particle raft is almost the same as that of water, but the equivalent contact angle of the rod attached to the particles is greatly enhanced. Finally, the model of an axisymmetrical rod pressing liquid is built, and the numerical result is in excellent agreement with the experimental data. These analyses may be beneficial to the measurement of mechanical behaviors for soft interfaces, separation of oil and water, flotation in minerals, and design of miniature boats.
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Affiliation(s)
- Pingcheng Zuo
- Department of Engineering Mechanics, College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China.
| | - Jianlin Liu
- Department of Engineering Mechanics, College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China.
| | - Shanpeng Li
- Department of Engineering Mechanics, College of Pipeline and Civil Engineering, China University of Petroleum (East China), Qingdao 266580, China.
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23
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Terpilowski K, Rymuszka D, Hołysz L, Ilnicki M. Surface properties of metal alloys used in aviation after plasma treatment. SURF INTERFACE ANAL 2017. [DOI: 10.1002/sia.6204] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Konrad Terpilowski
- Department of Physical Chemistry-Interfacial Phenomena, Faculty of Chemistry; Maria Curie-Sklodowska University; 20-031 Lublin Poland
| | - Diana Rymuszka
- Department of Physical Chemistry-Interfacial Phenomena, Faculty of Chemistry; Maria Curie-Sklodowska University; 20-031 Lublin Poland
| | - Lucyna Hołysz
- Department of Physical Chemistry-Interfacial Phenomena, Faculty of Chemistry; Maria Curie-Sklodowska University; 20-031 Lublin Poland
| | - Marek Ilnicki
- Chemical Advisory and Trade Sp. z o. o; Warszawa Poland
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24
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Suzuki S, Ueno K. Apparent Contact Angle Calculated from a Water Repellent Model with Pinning Effect. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:138-143. [PMID: 28001421 DOI: 10.1021/acs.langmuir.6b03832] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A set of new theoretical equations for apparent contact angles is proposed. The equations are derived from an equilibrium of interfacial tensions of a three-phase contact line pinned at the edges of a fine structure. These equations are validated by comparison with contact-angle measurement results for 2 μL water droplets on poly(methyl methacrylate) microstructured samples with square pillars or holes. The equilibrium contact angles predicted by the new equations reasonably agree with the experimental results. In contrast, the values predicted by the Cassie-Baxter equation or the Wenzel equation do not qualitatively agree with the experimental results in pillar pattern cases because the Cassie-Baxter equation and the Wenzel equation do not account for the pinning effect.
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Affiliation(s)
- Shojiro Suzuki
- Graduate School of Engineering, Iwate University , 4-3-5 Ueda, Morioka 020-8551, Japan
| | - Kazuyuki Ueno
- Graduate School of Engineering, Iwate University , 4-3-5 Ueda, Morioka 020-8551, Japan
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25
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Wang Y, Ma L, Xu X, Luo J. Expressions for the evaporation of sessile liquid droplets incorporating the evaporative cooling effect. J Colloid Interface Sci 2016; 484:291-297. [DOI: 10.1016/j.jcis.2016.09.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Revised: 09/06/2016] [Accepted: 09/06/2016] [Indexed: 11/29/2022]
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26
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Statistical Contact Angle Analyses with the High-Precision Drop Shape Analysis (HPDSA) Approach: Basic Principles and Applications. COATINGS 2016. [DOI: 10.3390/coatings6040057] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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27
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Tadmor R, Wasnik PS, N'guessan HE, Tadmor R, Tadmor M. Inducing arbitrary vapor pressures, and quantifying leakages. AIChE J 2016. [DOI: 10.1002/aic.15329] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Rafael Tadmor
- Dan F. Smith Dept. of Chemical Engineering; Lamar University; Beaumont TX 77710
| | - Priyanka S. Wasnik
- Dan F. Smith Dept. of Chemical Engineering; Lamar University; Beaumont TX 77710
| | | | - Rafael Tadmor
- Dept. of Chemical Engineering; Technion, Israel Institute of Technology; Haifa Israel
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28
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Cai ZB, Zhao L, Zhang X, Yue W, Zhu MH. Combined Effect of Textured Patterns and Graphene Flake Additives on Tribological Behavior under Boundary Lubrication. PLoS One 2016; 11:e0152143. [PMID: 27054762 PMCID: PMC4824447 DOI: 10.1371/journal.pone.0152143] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 03/09/2016] [Indexed: 12/01/2022] Open
Abstract
A ball-on-plate wear test was employed to investigate the effectiveness of graphene (GP) nanoparticles dispersed in a synthetic-oil-based lubricant in reducing wear. The effect by area ratio of elliptically shaped dimple textures and elevated temperatures were also explored. Pure PAO4 based oil and a mixture of this oil with 0.01 wt% GP were compared as lubricants. At pit area ratio of 5%, GP-base oil effectively reduced friction and wear, especially at 60 and 100 °C. Under pure PAO4 oil lubrication, the untextured surfaces gained low friction coefficients (COFs) and wear rates under 60 and 100 °C. With increasing laser--texture area ratio, the COF and wear rate decreased at 25 and 150 °C but increased at 60 and 100 °C. Under the GP-based oil lubrication, the textured surface with 5% area ratio achieved the lowest COF among those of the area ratios tested at all test temperatures. Meanwhile, the textured surface with 20% area ratio obtained the highest COF among those of the area ratios. With the joint action of GP and texture, the textured surface with 10% area ratio exhibited the best anti-wear performance among all of the textured surfaces at all test temperatures.
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Affiliation(s)
- Zhen-bing Cai
- Key Lab of Advanced Technologies of Materials (Ministry of Education), Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China
| | - Lei Zhao
- Key Lab of Advanced Technologies of Materials (Ministry of Education), Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China
| | - Xu Zhang
- Key Lab of Advanced Technologies of Materials (Ministry of Education), Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China
| | - Wen Yue
- Mechanical Engineering Department, School of Engineering and Technology, China University of Geosciences (Beijing), 100083, China
| | - Min-hao Zhu
- Key Lab of Advanced Technologies of Materials (Ministry of Education), Tribology Research Institute, Southwest Jiaotong University, Chengdu, 610031, China
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29
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Controlling arbitrary humidity without convection. J Colloid Interface Sci 2015; 455:212-9. [DOI: 10.1016/j.jcis.2015.04.072] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 04/23/2015] [Indexed: 01/24/2023]
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30
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Geometric Interpretation of Surface Tension Equilibrium in Superhydrophobic Systems. ENTROPY 2015. [DOI: 10.3390/e17074684] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Chen L, Lei J, Wang F, Wang G, Feng H. Facile synthesis of graphene sheets from fluorinated graphite. RSC Adv 2015. [DOI: 10.1039/c5ra00910c] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The chemical exfoliation of FGi by hydrazine hydrate to create graphene sheets.
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Affiliation(s)
- Li Chen
- College of Petrochemical Technology
- Lanzhou University of Technology
- Lanzhou 730050
- China
| | - Jiaojiao Lei
- College of Petrochemical Technology
- Lanzhou University of Technology
- Lanzhou 730050
- China
| | - Fuhui Wang
- College of Petrochemical Technology
- Lanzhou University of Technology
- Lanzhou 730050
- China
| | - Guochao Wang
- College of Petrochemical Technology
- Lanzhou University of Technology
- Lanzhou 730050
- China
| | - Huixia Feng
- College of Petrochemical Technology
- Lanzhou University of Technology
- Lanzhou 730050
- China
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32
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Ramachandran R, Nosonovsky M. Coupling of surface energy with electric potential makes superhydrophobic surfaces corrosion-resistant. Phys Chem Chem Phys 2015; 17:24988-97. [DOI: 10.1039/c5cp04462f] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The superhydrophobicity makes metallic surfaces corrosion-resistant. Hydrophobization leads to a decrease in the corrosion potential.
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Affiliation(s)
- Rahul Ramachandran
- Department of Mechanical Engineering
- College of Engineering & Applied Science
- University of Wisconsin-Milwaukee
- Milwaukee
- USA
| | - Michael Nosonovsky
- Department of Mechanical Engineering
- College of Engineering & Applied Science
- University of Wisconsin-Milwaukee
- Milwaukee
- USA
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33
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Pan S, Guo R, Xu W. Investigating and biomimicking the surface wetting behaviors of ginkgo leaf. SOFT MATTER 2014; 10:8800-8803. [PMID: 25299973 DOI: 10.1039/c4sm01844c] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
For the first time, the surface composite Cassie-Baxter wetting state is carefully investigated using ginkgo biloba as natural model. Investigations follow two directions: (a) low local solid contact areal fraction leading to high apparent contact angles; and (b) thick air plastron trapped at the contacting interface leading to stable dewetting state.
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Affiliation(s)
- Shuaijun Pan
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.
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34
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Zhang YN, Bortolani V, Mistura G. Influence of graphene coating on the adsorption and tribology of Xe on Au(1 1 1) substrate. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:445003. [PMID: 25243384 DOI: 10.1088/0953-8984/26/44/445003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The adsorption and tribological properties of graphene have received increasing attention for the further development of graphene-based coatings in applications. In this work, we performed first principles calculations with the inclusion of the nonlocal van der Waals correction to study the effect of graphene coating on the adsorption geometries, sliding frictions and electronic properties of Xe monolayer on the Au(1 1 1) substrate. The calculated activation energies indicate that Xe becomes movable on pure Au(1 1 1) surface at a temperature of around 30 K, whereas its motion can be activated only at a high temperature of ~50 K on graphene and on graphene-coated Au(1 1 1) substrates, in good agreement with recent experimental measurements by quartz crystal microbalance technique.
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Affiliation(s)
- Y N Zhang
- Chengdu Green Energy and Green Manufacturing Technology R&D Center, Sichuan, 620107, People's Republic of China. Beijing Computational Science Research Center, Beijing, 100084, People's Republic of China
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35
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Ramachandran R, Nosonovsky M. Surface micro/nanotopography, wetting properties and the potential for biomimetic icephobicity of skunk cabbage Symplocarpus foetidus. SOFT MATTER 2014; 10:7797-7803. [PMID: 25144747 DOI: 10.1039/c4sm01230e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Lotus (Nelumbo nucifera) is known for its two remarkable properties: superhydrophobicity and thermogenesis; however, the relationship between these two properties remains obscure. Most botanists agree that thermogenesis helps to attract pollinators, while non-wetting helps to catch pollinators and prevents contamination. Here we investigate the surface micro- and nanotopography and wetting properties of eastern skunk cabbage (Symplocarpus foetidus), another thermogenic plant, which is known for its ability to melt snow. The skunk cabbage leaves are hydrophobic but not superhydrophobic, and they have high contact angle hysteresis (similar to the rose petal effect). We develop a heat transfer model to relate icephobicity with heat transfer and discuss the biomimetic potential that both thermogenic and superhydrophobic plants may have for icephobicity in soft materials.
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Affiliation(s)
- Rahul Ramachandran
- College of Engineering & Applied Science, University of Wisconsin-Milwaukee, Milwaukee, WI 53211, USA.
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36
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Abstract
Graphene oxide (GO), a graphene-related material containing oxygen-functional groups, has attracted considerable attention because of its strongly hydrophilic behavior and potential use in GO-hybrid composites. We put our focus on the fabrication and rheological characteristics of GO-based electrorheological and magnetorheological smart fluids under electric and magnetic fields, respectively in this Highlight. A brief perspective on the significant role of GO in tribology and the amphiphilic characteristics of Pickering emulsions are also included.
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Affiliation(s)
- Wen Ling Zhang
- Department of Polymer Science and Engineering, Inha University, Incheon 402-751, Korea.
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37
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Hejazi V, Moghadam AD, Rohatgi P, Nosonovsky M. Beyond Wenzel and Cassie-Baxter: second-order effects on the wetting of rough surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9423-9429. [PMID: 25051526 DOI: 10.1021/la502143v] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The Wenzel and Cassie-Baxter models are almost exclusively used to explain the contact angle dependence of the structure of rough and patterned solid surfaces. However, these two classical models do not always accurately predict the wetting properties of surfaces since they fail to capture the effect of many interactions occurring during wetting, including, for example, the effect of the disjoining pressure and of crystal microstructure, grains, and defects. We call such effects the second-order effects and present here a model showing how the disjoining pressure isotherm can affect wettability due to the formation of thin liquid films. We measure water contact angles on pairs of metallic surfaces with nominally the same Wenzel roughness obtained by abrasion and by chemical etching. These two methods of surface roughening result in different rough surface structure, thus leading to different values of the contact angle, which cannot be captured by the Wenzel- and Cassie-type models. The chemical and physical changes that occur on the stainless steel and aluminum alloy surfaces as a result of intergranular corrosion, along with selective intermetallic dissolution, lead to a surface roughness generated on the nano- and microscales.
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Affiliation(s)
- Vahid Hejazi
- College of Engineering & Applied Science, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53211, United States
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38
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Pittoni PG, Lin CH, Yu TS, Lin SY. On the uniqueness of the receding contact angle: effects of substrate roughness and humidity on evaporation of water drops. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:9346-9354. [PMID: 25029610 DOI: 10.1021/la501455d] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Could a unique receding contact angle be indicated for describing the wetting properties of a real gas-liquid-solid system? Could a receding contact angle be defined if the triple line of a sessile drop is not moving at all during the whole measurement process? To what extent is the receding contact angle influenced by the intrinsic properties of the system or the measurement procedures? In order to answer these questions, a systematic investigation was conducted in this study on the effects of substrate roughness and relative humidity on the behavior of pure water drops spreading and evaporating on polycarbonate (PC) surfaces characterized by different morphologies. Dynamic, advancing, and receding contact angles were found to be strongly affected by substrate roughness. Specifically, a receding contact angle could not be measured at all for drops evaporating on the more rugged PC surfaces, since the drops were observed strongly pinning to the substrate almost until their complete disappearance. Substrate roughness and system relative humidity were also found responsible for drastic changes in the depinning time (from ∼10 to ∼60 min). Thus, for measurement observations not sufficiently long, no movement of the triple line could be noted, with, again, the failure to find a receding contact angle. Therefore, to keep using concepts such as the receding contact angle as meaningful specifications of a given gas-liquid-solid system, the imperative to carefully investigate and report the inner characteristics of the system (substrate roughness, topography, impurities, defects, chemical properties, etc.) is pointed out in this study. The necessity of establishing methodological standards (drop size, measurement method, system history, observation interval, relative humidity, etc.) is also suggested.
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Affiliation(s)
- Paola G Pittoni
- Department of Chemical Engineering National Taiwan University of Science and Technology , 43 Keelung Road, Section 4, Taipei 106, Taiwan
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Bajaj P, Rivera JA, Marchwiany D, Solovyeva V, Bashir R. Graphene-based patterning and differentiation of C2C12 myoblasts. Adv Healthc Mater 2014; 3:995-1000. [PMID: 24352858 DOI: 10.1002/adhm.201300550] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2013] [Indexed: 11/09/2022]
Abstract
This study aims at generating highly aligned functional myotubes using graphene as the underlying scaffold. Graphene not only supports the growth of C2C12 muscle cells but also enhances its differentiation and leads to spontaneous patterning of myotubes.
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Affiliation(s)
- Piyush Bajaj
- Department of Bioengineering; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
- Micro and Nanotechnology Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
| | - Jose A. Rivera
- Department of Bioengineering; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
- Micro and Nanotechnology Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
| | - Daniel Marchwiany
- Micro and Nanotechnology Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
- Department of Molecular and Cellular Biology; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
| | - Vita Solovyeva
- Micro and Nanotechnology Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
- Department of Electrical and Computer Engineering; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
| | - Rashid Bashir
- Department of Bioengineering; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
- Micro and Nanotechnology Laboratory; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
- Department of Electrical and Computer Engineering; University of Illinois at Urbana-Champaign; Urbana IL 61801 USA
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Free-decay and resonant methods for investigating the fundamental limit of superhydrophobicity. Nat Commun 2014; 4:2398. [PMID: 24025991 DOI: 10.1038/ncomms3398] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Accepted: 08/05/2013] [Indexed: 11/08/2022] Open
Abstract
The recently demonstrated extremely water-repellent surfaces with contact angles close to 180° with nearly zero hysteresis approach the fundamental limit of non-wetting. The measurement of the small but non-zero energy dissipation of a droplet moving on such a surface is not feasible with the contemporary methods, although it would be needed for optimized technological applications related to dirt repellency, microfluidics and functional surfaces. Here we show that magnetically controlled freely decaying and resonant oscillations of water droplets doped with superparamagnetic nanoparticles allow quantification of the energy dissipation as a function of normal force. Two dissipative forces are identified at a precision of ~ 10 nN, one related to contact angle hysteresis near the three-phase contact line and the other to viscous dissipation near the droplet-solid interface. The method is adaptable to common optical goniometers and facilitates systematic and quantitative investigations of dynamical superhydrophobicity, defects and inhomogeneities on extremely superhydrophobic surfaces.
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Madani S, Amirfazli A. Oil drop shedding from solid substrates by a shearing liquid. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2013.04.058] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Flores-Vivian I, Hejazi V, Kozhukhova MI, Nosonovsky M, Sobolev K. Self-assembling particle-siloxane coatings for superhydrophobic concrete. ACS APPLIED MATERIALS & INTERFACES 2013; 5:13284-13294. [PMID: 24245777 DOI: 10.1021/am404272v] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We report here, for the first time in the literature, a method to synthesize hydrophobic and superhydrophobic concrete. Concrete is normally a hydrophilic material, which significantly reduces the durability of concrete structures and pavements. To synthesize water-repellent concrete, hydrophobic emulsions were fabricated and applied on portland cement mortar tiles. The emulsion was enriched with the polymethyl-hydrogen siloxane oil hydrophobic agent as well as metakaolin (MK) or silica fume (SF) to induce the microroughness and polyvinyl alcohol (PVA) fibers to create hierarchical surfaces. Various emulsion types were investigated by using different mixing procedures, and single- and double-layer hydrophobic coatings were applied. The emulsions and coatings were characterized with optical microscope and scanning electron microscope (SEM), and their wetting properties, including the water contact angle (CA) and roll-off angle, were measured. A theoretical model for coated and non-coated concrete, which can be generalized for other types of materials, was developed to predict the effect of surface roughness and composition on the CA. An optimized distance between the aggregates was found where the CA has the highest value. The maximal CA measured was 156° for the specimen with PVA fibers treated with MK based emulsion. Since water penetration is the main factor leading to concrete deterioration, hydrophobic water-repellent concretes have much longer durability then regular concretes and can have a broad range of applications in civil and materials engineering.
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Affiliation(s)
- Ismael Flores-Vivian
- Department of Civil Engineering and Mechanics and ‡Department of Mechanical Engineering, University of Wisconsin , Milwaukee, Wisconsin, 53201, United States
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Tadmor R. Misconceptions in wetting phenomena. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:15474-15475. [PMID: 24256467 DOI: 10.1021/la403578q] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
In a recent paper ('t Mannetje, D.; Banpurkar, A.; Koppelman, H.; Duits, M. H. G.; van den Ende, D.; Mugele, F. Electrically Tunable Wetting Defects Characterized by a Simple Capillary Force Sensor. Langmuir 2013, 29, 9944-9949), there are a few misconceptions regarding the interpretations of theories emanating from Shanahan and de Gennes in describing centrifugal adhesion balance (CAB) experiments, making their results seemingly contradictory to the theory. These are clarified here. We show that their results, if interpreted correctly, do not contradict the theories mentioned above.
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Affiliation(s)
- Rafael Tadmor
- Dan F. Smith Department of Chemical Engineering, Lamar University , Beaumont, Texas 77710, United States
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Sarkar A, Kietzig AM. General equation of wettability: A tool to calculate the contact angle for a rough surface. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.04.055] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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