1
|
Tümer EH, Erbil HY, Akdoǧan N. Wetting of Superhydrophobic Polylactic Acid Micropillared Patterns. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2022; 38:10052-10064. [PMID: 35930742 PMCID: PMC9387099 DOI: 10.1021/acs.langmuir.2c01708] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Revised: 07/27/2022] [Indexed: 06/10/2023]
Abstract
Superhydrophobic (SH) polylactic acid (PLA) surfaces were previously produced by various methods and used especially in biomedical applications and oil/water separation processes after 2008. However, the wettability of SH-PLA patterns containing micropillars has not been investigated before. In this study, PLA patterns having regular microstructured pillars with 12 different pillar diameters and pillar-to-pillar distances were prepared by hot pressing pre-flattened PLA sheets onto preformed polydimethylsiloxane (PDMS) soft molds having micro-sized pits. PDMS templates were previously prepared by photolithography using SU-8 molds. Apparent, advancing, and receding water contact angle measurements were carried out on the PLA patterns containing micropillars, and the morphology of the patterns was examined by optical and SEM microscopy. The largest contact angle obtained without the surface modification of the pure PLA pattern was 139°. Then, PLA micropatterns were hydrophobized using three types of silanes via chemical vapor deposition method, and SH-PLA patterns were obtained having θs of up to 167°. It was found that the highest θ values could be obtained when PLA pattern samples were coated with a silane containing a fluorine atom in its chemical structure. Washing and service life stability tests were also performed on the coated pattern samples and all of the silane coatings on the PLA patterns were found to be resistant over a 6 month period.
Collapse
Affiliation(s)
- Eda Hazal Tümer
- Department
of Chemical Engineering, Gebze Technical
University, Gebze, Kocaeli 41400, Türkiye
| | - H. Yildirim Erbil
- Department
of Chemical Engineering, Gebze Technical
University, Gebze, Kocaeli 41400, Türkiye
| | - Numan Akdoǧan
- Department
of Physics, Gebze Technical University, Gebze, Kocaeli 41400, Türkiye
| |
Collapse
|
2
|
Wang J, Xing Y, Gui X, Li G, Cao Y. Experimental and molecular dynamics simulation study on wetting interaction between water droplets and kaolinite surface. Chem Phys Lett 2022. [DOI: 10.1016/j.cplett.2022.139659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
3
|
|
4
|
|
5
|
Rohrs C, Azimi A, He P. Wetting on Micropatterned Surfaces: Partial Penetration in the Cassie State and Wenzel Deviation Theoretically Explained. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15421-15430. [PMID: 31663751 DOI: 10.1021/acs.langmuir.9b03002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A liquid droplet on a micropatterned substrate equalizes into either the Cassie-Baxter (also called Cassie for short) or the Wenzel state. This paper investigates the wetting phenomena on ideal micropatterned surfaces consisting of straight micropillars at different pillar dimensions and spacings (the word "ideal" refers to being chemically homogeneous and free of submicron-scale roughness all over the micropatterned surface). Two modeling approaches are used: (1) a thermodynamic approach analyzing the Gibbs energy of the droplet-solid-gas system and (2) a computational fluid dynamics (CFD) approach studying the three-dimensional dynamic wetting process to validate the results of the first approach. The thermodynamic approach incorporates three creative submodels proposed in this paper: (i) a sagging model explaining the pillar edge effect, (ii) a touchdown model transitioning the droplet's partial penetrating condition toward its full penetrating condition, i.e., the Wenzel state, and (iii) a liquid-volume model dynamically computing the liquid volume between the pillar valleys while in the partial penetrating condition or in the Wenzel state. The results of the thermodynamic approach reveal (1) a small energy barrier between the Cassie and Wenzel states, (2) no partial penetration and sagging of the liquid in the Cassie state on the ideal straight micropillared surface, and (3) that the apparent contact angle in the most stable Wenzel state can be 5° or more lower than the prediction of the Wenzel equation when the pillar height is equal or greater than 75 μm. To the best of our knowledge, this paper presents the theoretical explanation of this Wenzel deviation on micropatterned surfaces for the first time in the literature. Utilizing the state-of-the-art continuum model developed by the authors in previous studies, the CFD approach investigates the same wetting conditions and confirms the same findings.
Collapse
Affiliation(s)
- Chae Rohrs
- Department of Mechanical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Arash Azimi
- Department of Mechanical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| | - Ping He
- Department of Mechanical Engineering , Lamar University , Beaumont , Texas 77710 , United States
| |
Collapse
|
6
|
Subianto S, Li C, Rubin de Celis Leal D, Rana S, Gupta S, He R, Venkatesh S, Sutti A. Optimizing a High-Entropy System: Software-Assisted Development of Highly Hydrophobic Surfaces using an Amphiphilic Polymer. ACS OMEGA 2019; 4:15912-15922. [PMID: 31592461 PMCID: PMC6776970 DOI: 10.1021/acsomega.9b01978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Accepted: 08/21/2019] [Indexed: 05/04/2023]
Abstract
In materials science, the investigation of a large and complex experimental space is time-consuming and thus may induce bias to exclude potential solutions where little to no knowledge is available. This work presents the development of a highly hydrophobic material from an amphiphilic polymer through a novel, adaptive artificial intelligence approach. The hydrophobicity arises from the random packing of short polymer fibers into paper, a highly entropic, multistep process. Using Bayesian optimization, the algorithm is able to efficiently navigate the parameter space without bias, including areas which a human experimenter would not address. This resulted in additional knowledge gain, which can then be applied to the fabrication process, resulting in a highly hydrophobic material (static water contact angle 135°) from an amphiphilic polymer (contact angle of 90°) through a simple and scalable filtration-based method. This presents a potential pathway for surface modification using the short polymer fibers to create fluorine-free hydrophobic surfaces on a larger scale.
Collapse
Affiliation(s)
- Surya Subianto
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
- E-mail: (S.S.)
| | - Cheng Li
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
| | - David Rubin de Celis Leal
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
| | - Santu Rana
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
| | - Sunil Gupta
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
| | - Rongliang He
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
| | - Svetha Venkatesh
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
| | - Alessandra Sutti
- Institute
for Frontier Materials and Applied Artificial Intelligence
Institute, Deakin University, Geelong 3220, Australia
- E-mail: (A.S.)
| |
Collapse
|
7
|
Nowicki W. The interfacial energy in the Cassie-Baxter regime on the pyramid decorated solid surface. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2019; 42:84. [PMID: 31267331 DOI: 10.1140/epje/i2019-11848-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 06/04/2019] [Indexed: 06/09/2023]
Abstract
The wettability of the solid surface covered with a pattern of pyramids is studied in categories of behavior of a single liquid droplet settled onto such a surface. The Cassie-Baxter regime of wetting is assumed. The cellular model of liquid-solid interface has been proposed. On the basis of the calculations for a single elemental cell with applied periodic boundary conditions, the components of the interfacial energy have been obtained. The dependence of the interfacial energy and hypothetical pseudo-contact angle on the hydrostatic pressure is discussed. The influence of the line tension on the wettability of the surface, expressed in terms of the apparent contact angle is shown.
Collapse
Affiliation(s)
- Waldemar Nowicki
- Faculty of Chemistry, Adam Mickiewicz University, Umultowska 89b, 61-714, Poznań, Poland.
| |
Collapse
|
8
|
Gregorčič P, Conradi M, Hribar L, Hočevar M. Long-Term Influence of Laser-Processing Parameters on (Super)hydrophobicity Development and Stability of Stainless-Steel Surfaces. MATERIALS 2018; 11:ma11112240. [PMID: 30423878 PMCID: PMC6266256 DOI: 10.3390/ma11112240] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/24/2018] [Revised: 11/07/2018] [Accepted: 11/09/2018] [Indexed: 12/05/2022]
Abstract
Controlling the surface wettability represents an important challenge in the field of surface functionalization. Here, the wettability of a stainless-steel surface is modified by 30-ns pulses of a Nd:YAG marking laser (λ = 1064 nm) with peak fluences within the range 3.3–25.1 J cm−2. The short- (40 days), intermediate- (100 days) and long-term (1 year) superhydrophilic-to-(super)hydrophobic transition of the laser-textured surfaces exposed to the atmospheric air is examined by evaluating its wettability in the context of the following parameters: (i) pulse fluence; (ii) scan line separation; (iii) focal position and (iv) wetting period due to contact angle measurements. The results show that using solely a short-term evaluation can lead to wrong conclusions and that the faster development of the hydrophobicity immediately after laser texturing usually leads to lower final contact angle and vice versa, the slower this transition is, the more superhydrophobic the surface is expected to become (possibly even with self-cleaning ability). Depending on laser fluence, the laser-textured surfaces can develop stable or unstable hydrophobicity. Stable hydrophobicity is achieved, if the threshold fluence of 12 J cm−2 is exceeded. We show that by nanosecond-laser texturing a lotus-leaf-like surface with a contact angle above 150° and roll-off angle below 5° can be achieved.
Collapse
Affiliation(s)
- Peter Gregorčič
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia.
| | - Marjetka Conradi
- Institute of metals and technology, Lepi pot 11, 1000 Ljubljana, Slovenia.
| | - Luka Hribar
- Faculty of Mechanical Engineering, University of Ljubljana, Aškerčeva 6, 1000 Ljubljana, Slovenia.
| | - Matej Hočevar
- Institute of metals and technology, Lepi pot 11, 1000 Ljubljana, Slovenia.
| |
Collapse
|
9
|
Snustad I, Røe IT, Brunsvold A, Ervik Å, He J, Zhang Z. A review on wetting and water condensation - Perspectives for CO 2 condensation. Adv Colloid Interface Sci 2018; 256:291-304. [PMID: 29653667 DOI: 10.1016/j.cis.2018.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 03/09/2018] [Accepted: 03/19/2018] [Indexed: 11/26/2022]
Abstract
Liquefaction of vapor is a necessary, but energy intensive step in several important process industries. This review identifies possible materials and surface structures for promoting dropwise condensation, known to increase efficiency of condensation heat transfer. Research on superhydrophobic and superomniphobic surfaces promoting dropwise condensation constitutes the basis of the review. In extension of this, knowledge is extrapolated to condensation of CO2. Global emissions of CO2 need to be minimized in order to reduce global warming, and liquefaction of CO2 is a necessary step in some carbon capture, transport and storage (CCS) technologies. The review is divided into three main parts: 1) An overview of recent research on superhydrophobicity and promotion of dropwise condensation of water, 2) An overview of recent research on superomniphobicity and dropwise condensation of low surface tension substances, and 3) Suggested materials and surface structures for dropwise CO2 condensation based on the two first parts.
Collapse
|
10
|
Lehr J, Kietzig AM. Dependence of capillary forces on relative humidity and the surface properties of femtosecond laser micromachined titanium. J Colloid Interface Sci 2015; 448:356-66. [PMID: 25746189 DOI: 10.1016/j.jcis.2015.02.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 02/10/2015] [Accepted: 02/16/2015] [Indexed: 12/01/2022]
Abstract
Capillary forces were measured with colloidal atomic force microscopy at different levels of relative humidity on femtosecond laser micromachined titanium surfaces. After laser machining at different intensity levels, the titanium surfaces show a nanoscale ripple topology or microscopic bumpy structures. Different machining environments were chosen to influence the surface chemistry in addition to topology: while machining in pure oxygen and water resulted in surfaces consisting of TiO2, a composite surface of TiO2 and TiN was obtained after machining in pure nitrogen. All samples were subsequently exposed to pure oxygen, carbon dioxide or water, and showed different levels of wettability and capillary force. We have introduced the concept of humidity sensitivity as the relative increase of the capillary force with respect to the measured force at 0% humidity. We report that samples with a nanoscale ripple topology machined in pure oxygen exhibit the lowest level of capillary force and the lowest sensitivity towards humidity in the environment. Surfaces with low sensitivity towards changes of the relative humidity are good candidates for technical applications, where capillary forces have to be controlled. This study contributes to the development of such surfaces, to a better understanding of how capillary bridges are formed on rough surfaces and ultimately to the exploration of the relationship between surface wettability and capillary forces.
Collapse
Affiliation(s)
- Jorge Lehr
- Department of Chemical Engineering, McGill University, 3610 University Street, H3A 0C5 Montreal, QC, Canada
| | - Anne-Marie Kietzig
- Department of Chemical Engineering, McGill University, 3610 University Street, H3A 0C5 Montreal, QC, Canada
| |
Collapse
|
11
|
Sarkar A, Kietzig AM. Design of a robust superhydrophobic surface: thermodynamic and kinetic analysis. SOFT MATTER 2015; 11:1998-2007. [PMID: 25627327 DOI: 10.1039/c4sm02787f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The design of a robust superhydrophobic surface is a widely pursued topic. While many investigations are limited to applications with high impact velocities (for raindrops of the order of a few meters per second), the essence of robustness is yet to be analyzed for applications involving quasi-static liquid transfer. To achieve robustness with high impact velocities, the surface parameters (geometrical details, chemistry) have to be selected from a narrow range of permissible values, which often entail additional manufacturing costs. From the dual perspectives of thermodynamics and mechanics, we analyze the significance of robustness for quasi-static drop impact, and present the range of permissible surface characteristics. For surfaces with a Young's contact angle greater than 90° and square micropillar geometry, we show that robustness can be enforced when an intermediate wetting state (sagged state) impedes transition to a wetted state (Wenzel state). From the standpoint of mechanics, we use available scientific data to prove that a surface with any topology must withstand a pressure of 117 Pa to be robust. Finally, permissible values of surface characteristics are determined, which ensure robustness with thermodynamics (formation of a sagged state) and mechanics (withstanding 117 Pa).
Collapse
Affiliation(s)
- Anjishnu Sarkar
- Department of Chemical Engineering, McGill University, Montreal, Canada.
| | | |
Collapse
|
12
|
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.
Collapse
Affiliation(s)
- Paola G Pittoni
- Department of Chemical Engineering National Taiwan University of Science and Technology , 43 Keelung Road, Section 4, Taipei 106, Taiwan
| | | | | | | |
Collapse
|
13
|
Gharabaghi M, Aghazadeh S. A review of the role of wetting and spreading phenomena on the flotation practice. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2014.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|