ORCID Profile
0000-0002-2941-5731
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Nanotechnology | Colloid And Surface Chemistry | Nanotechnology | Physical Chemistry (Incl. Structural) | Chemical Engineering not elsewhere classified | Polymers and Plastics | Electrochemistry | Mineral Processing | Petroleum And Reservoir Engineering | Nanotechnology not elsewhere classified | Nanoscale Characterisation | Petrophysics
ANZSRC Socio-Economic Objective (SEO)
Chemical sciences | Concentrating processes of other base metal ores | Energy transformation | Oil and gas | Expanding Knowledge in the Chemical Sciences | Metals (composites, coatings, bonding, etc.) | Expanding Knowledge in the Physical Sciences | Earth sciences | Physical sciences |
Related Links
Publications
The interfacial conformation of polypropylene glycols and their foam properties
Publisher: Elsevier BV
Date: 05-2006
The uniform capillary model for packed beds and particle wettability
Publisher: Elsevier BV
Date: 09-2009
DOI: 10.1016/J.JCIS.2009.04.086
Abstract: The distribution and movement of fluids in porous media are important in a variety of situations arising naturally and industrially (e.g., water migration in soils, oil recovery, chromatography, filtration and separation processes). Our specific interest is in deriving advancing and receding contact angles from capillary pressure measurements in packed beds of particles partially saturated with liquids. The simplest model of a porous medium treats the porous body as an equivalent uniform capillary giving rise to the same capillary pressure. Pressure measurements were performed successfully with advancing as well as receding liquids. For an advancing liquid front a measurement with a second liquid is needed to calibrate the equivalent capillary radius and obtain the advancing contact angle. For a receding liquid front--an additional determination of the amount of liquid trapped behind in smaller pores is required. The equivalent capillary radius is mainly determined by the porosity of the packed bed and is easily corrected to account for capillary retention. Only then can the receding contact angle be obtained reliably. This new methodology for contact angle measurement was validated with model systems and applied successfully to various real particulate systems.
The interfacial conformation of polypropylene glycols and foam behaviour
Publisher: Elsevier BV
Date: 12-2004
Differential Capacitance of the Electrical Double Layer in Imidazolium-Based Ionic Liquids: Influence of Potential, Cation Size, and Temperature
Publisher: American Chemical Society (ACS)
Date: 19-04-2008
DOI: 10.1021/JP7100732
Small surface nanotopography encourages fibroblast and osteoblast cell adhesion
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3RA23193C
Contact Line Motion on Nanorough Surfaces: A Thermally Activated Process
Publisher: American Chemical Society (ACS)
Date: 03-05-2013
DOI: 10.1021/JA3104846
Abstract: The motion of a solid-liquid-liquid contact line over nanorough surfaces is investigated. The surface nanodefects are varied in size, density, and shape. The dynamics of the three-phase contact line on all nanorough substrates studied is thermally activated. However, unlike the motion of a liquid-vapor interface over smooth surfaces, this thermally activated process is not adequately described by the molecular kinetic theory. The molecular parameters extracted from the experiments suggest that on the nanorough surfaces, the motion of the contact line is unlikely to simply consist of molecular adsorption-desorption steps. Thermally activated pinning-depinning events on the surface nanodefects are also important. We investigate the effect of surface nanotopography on the relative importance of these two mechanisms in governing contact line motion. Using a derivation for the hysteresis energy based on Joanny and de Gennes's model, we evaluate the effect of nanotopographical features on the wetting activation free energy and contact line friction. Our results suggest that both solid-liquid interactions and surface pinning strength contribute to the energy barriers hindering the three-phase contact line motion. For relatively low nanodefect densities, the activation free energy of wetting can be expressed as a sum of surface wettability and surface topography contributions, thus providing a direct link between contact line dynamics and roughness parameters.
Foaming of polypropylene glycols and glycol/MIBC mixtures
Publisher: Elsevier BV
Date: 02-2005
Yielding and fracturing of concentrated emulsions in narrow gaps
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3SM50314C
Experimental investigations of the wettability of clays and shales
Publisher: American Geophysical Union (AGU)
Date: 07-2009
DOI: 10.1029/2008JB005928
Influence of the Electrical Double Layer in Electrowetting
Publisher: American Chemical Society (ACS)
Date: 08-01-2003
DOI: 10.1021/JP0216326
Marangoni effects in aqueous polypropylene glycol foams
Publisher: Elsevier BV
Date: 06-2005
DOI: 10.1016/J.JCIS.2005.01.028
Abstract: The foam behavior of three polypropylene glycols covering the molecular weight range between 192 and 725 g/mol has been examined. Static and dynamic surface tension data, as well as bubble size distribution and retention time in the foam, were incorporated into a simple model of foam stability. The latter clearly indicates that surface tension differences between the plateau border and lamellar region adjacent to the bubble surface are the dominant factor in controlling foamability, causing liquid flow in the direction opposite to liquid drainage, a process termed the Marangoni effect.
Contact Angles of a Brine on a Bituminous Coal in Compressed Hydrogen
Publisher: American Geophysical Union (AGU)
Date: 22-04-2022
DOI: 10.1029/2022GL098261
Abstract: Hydrogen storage is a main issue in the establishment of a hydrogen economy. Geo‐storage could be a viable solution if hydrogen could be injected into and withdrawn from suitable geological formations, reversibly and reliably. Rock wettability is a major factor as it affects injectivities, withdrawal rates, storage capacities, and containment security. We report here the contact angles of a brine on the surface of a bituminous coal in a pressurized hydrogen atmosphere. Under realistic geo‐storage conditions the coal surface was weakly water‐wet. Hydrogen pressure increased brine contact angles at 25°C but did not have an impact at 50 or 70°C. We present a thermodynamic model that describes the observed behavior. Our results would support the development of large‐scale geo‐storage technologies for hydrogen.
Fabrication of silica-on-titania and titania-on-silica nanoparticle assemblies
Publisher: Elsevier BV
Date: 2007
Tuning and predicting the wetting of nanoengineered material surface
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C5NR08329J
Abstract: A model predicting the wettability of nanorough substrates with re-entrant geometry is developed using substrata with controlled nanotopography and chemistry.
Rolling, penetration and evaporation of alcohol-water drops on coarse and fine hydrophobic powders
Publisher: Elsevier BV
Date: 09-2013
Influence of Surface Charge on Wetting Kinetics
Publisher: American Chemical Society (ACS)
Date: 14-10-2010
DOI: 10.1021/LA103351T
Abstract: The wettability of a titania surface, partially covered with octadecyltrihydrosilane, has been investigated as a function of solution pH. The results show that surface charge affects both static wettability and wetting kinetics. The static contact angle decreases above and below the point of zero charge of the titania surface in a Lippman-like manner as the pH is altered. The dependence of dynamic contact angle on velocity is also affected by pH. The molecular-kinetic theory (MKT) is used to interpret the dynamic contact angle data. The frequency of molecular displacement κ(0) strongly varies with surface charge, whereas the mean molecular displacement length λ is essentially unaffected. There is an exponential dependence of contact-line friction upon work of adhesion, which is varied simply by altering the pH.
Contact Line Friction in Liquid–Liquid Displacement on Hydrophobic Surfaces
Publisher: American Chemical Society (ACS)
Date: 29-11-2011
DOI: 10.1021/JP209140A
Electrostatics and Metal Oxide Wettability
Publisher: American Chemical Society (ACS)
Date: 12-07-2011
DOI: 10.1021/JP203714A
Influence of the Work of Adhesion on the Dynamic Wetting of Chemically Heterogeneous Surfaces
Publisher: American Chemical Society (ACS)
Date: 25-10-2008
DOI: 10.1021/LA802264D
Abstract: The velocity dependence of the dynamic contact angle for a glycerol-water mixture wetting two different chemically heterogeneous surfaces (mixed thiols on gold and partially methylated titania, 16 s les in all) was studied. The molecular kinetic theory (MKT) of wetting was used to interpret the dynamic contact angle data. The equilibrium displacement frequency ( K 0) was predominantly determined by the viscous contribution from the bulk liquid, with a minor contribution from the surface. The mean distance between surface sites (lambda) decreased with increasing work of adhesion. The contact line friction coefficient zeta 0 was found to vary exponentially with the work of adhesion, enabling the unit flow volume of the liquid to be obtained.
The formation and stability of self-assembled monolayers of octadecylphosphonic acid on titania
Publisher: Elsevier BV
Date: 12-2006
Orientation and mutual location of ions at the surface of ionic liquids
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CP00683A
Abstract: The structure of the liquid-vacuum interface in room temperature ionic liquids (ILs) is investigated using angle-resolved X-ray photoelectron spectroscopy (ARXPS) and synchrotron X-ray photoelectron spectroscopy (SXPS). By varying the polar angle and comparing the results for the chosen ionic liquids, we identify the presence of a surface layer that is chemically different to the bulk. In particular, this layer: (i) is enriched by aliphatic carbon atoms from the saturated carbon chains of the anions and cations, and (ii) contains an unequal distribution of cations and anions in a direction normal to the surface. This unequal distribution creates a potential gradient which extends from the surface into the liquid. We show unequivocally that this layer is not due to the presence of impurities.
The unusual surface chemistry of α-Al2O3 (0001)
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C001222J
Abstract: We report on the influence of heat treatment on the surface chemistry of an α-alumina crystal. We compare its electrical double layer behaviour with that of 150 nm diameter α-Al(2)O(3) particles. Surface spectroscopy and zeta potential studies are used to understand the changes in surface chemistry. The pH(pzc) of an α-Al(2)O(3) (0001) single crystal (∼4) is more acidic than that of α-Al(2)O(3) particles (8.5), a difference explained by the dominance of [triple bond, length as m-dash]Al(2)OH surface groups on the single crystals and their charging behaviour. Heat treatment of the alumina surface causes a substantial decrease in the number of surface OH groups. Heating at 500 °C decreases the surface density of hydroxyl groups. Heating at 1050 °C also affects surface morphology and surface chemistry. The increased magnitude of the zeta potential and the pH(pzc) shift to lower pH suggest a surface reconstruction and the appearance of more acidic aluminium sites.
Structure-induced spreading of liquid in micropillar arrays
Publisher: Springer Science and Business Media LLC
Date: 17-08-2011
Electrowetting of Ionic Liquids
Publisher: American Chemical Society (ACS)
Date: 09-02-2006
DOI: 10.1021/JA057606D
Abstract: We have successfully demonstrated that imidazolium- and pyrrolidinium-based commercial room-temperature ionic liquids can electrowet (with a dc voltage) a smooth fluoropolymer (Teflon AF1600) surface. Qualitatively, the process is analogous to the electrowetting of aqueous electrolyte solutions: the contact angle versus voltage curve has a parabolic shape which saturates at larger voltages (positive or negative). On the other hand we observed several peculiarities: (i) the efficiency is significantly lower (by about an order of magnitude) (ii) the influence of the bulky cation is larger and the importance of the smaller anion is lesser, especially with respect to electrowetting saturation (iii) there is an asymmetry in the saturation contact angles found for positive and negative voltages. The asymmetry may be correlated with the cation-anion asymmetry of the ionic liquids. The low efficiency may be caused by the presence of water and other impurities in these commercial materials.
A quantitative experimental study of wetting hysteresis on discrete and continuous chemical heterogeneities
Publisher: Springer Science and Business Media LLC
Date: 03-10-2012
Precipitation of Drug Particles Using a Gas Antisolvent Process on a High-Pressure Microfluidic Platform
Publisher: American Chemical Society (ACS)
Date: 02-06-2020
Differential capacitance of the double layer at the electrode/ionic liquids interface
Publisher: Royal Society of Chemistry (RSC)
Date: 2010
DOI: 10.1039/C0CP00170H
Abstract: The differential capacitance of the electrical double layer at glassy carbon, platinum and gold electrodes immersed in various ionic liquids was measured using impedance spectroscopy. We discuss the influence of temperature, the composition of the ionic liquids and the electrode material on the differential capacitance otential curves. For different systems these curves have various overall shapes, but all include several extremes and a common minimum near the open circuit potential. We attribute this minimum to the potential of zero charge (PZC). Significantly, the differential capacitance generally decreases if the applied potential is large and moving away from the PZC. This is attributed to lattice saturation [A. A. Kornyshev, J. Phys. Chem. B, 2007, 111, 5545] effects which result in a thicker double layer. The differential capacitance of the double layer grows and specific adsorption diminishes with increasing temperature. Specific adsorption of both cations and anions influences the shapes of curves close to the PZC. The general shape of differential capacitance otential does not depend strongly on the identity of the electrode material.
Thermally- and Photoinduced Changes in the Water Wettability of Low-Surface-Area Silica and Titania
Publisher: American Chemical Society (ACS)
Date: 15-02-2005
DOI: 10.1021/LA047721M
Abstract: The surface properties of silica and titania are mainly determined by the presence, density, and type of terminal hydroxyl groups (Si-OH "silanol" and Ti-OH "titanol"). Thermal treatment at elevated temperatures causes dehydroxylation on both surfaces, confirmed by streaming potential and ToF-SIMS measurements. The magnitude of the zeta potential markedly decreases after heat treatment, but the IEP is not affected. The intensity ratio MOH(+)/M(+) (M = Si or Ti), which reflects the surface density of OH groups, also decreases noticeably after high-temperature treatment. The mechanism is condensation of adjacent silanol/titanol groups into siloxane/titanoxane bonds. Ultraviolet light (lambda = 254 nm) has little effect on silica but rapidly induces hydrophilicity on titania surfaces. There is a strong correlation between the amount of hydrocarbons adsorbed on the surface and the density of titanol groups (thence the water contact angle). The effect of UV radiation can be entirely attributed to photolytic decomposition of organic contaminants. Dehydroxylated titania and silica (at 1050 degrees C) show very different wetting behavior: silica is moderately hydrophobic (water contact angle of about 40 degrees), while titania is hydrophilic (0 degrees). This dissimilarity can be explained with a simple model estimating the van der Waals and acid-base interfacial interactions.
Directed crystallisation of zinc oxide on patterned surfaces
Publisher: Elsevier BV
Date: 11-2006
DOI: 10.1016/J.JCIS.2006.07.078
Abstract: Patterned self-assembled monolayers of functionalised alkane thiols were prepared on gold substrates, using UV-photolithography. Two alkane thiols, 11-mercaptoundecanoic acid (MUA) and a fluorinated decane thiol (FDT, CF3(CF2)7CH2CH2SH) were used to fabricate chemically structured surfaces which served as templates for zinc oxide (ZnO) crystallisation. When these patterns, containing high (MUA) and low (FDT) surface energy regions were exposed to a 10 mM zinc nitrate crystallising solution, nucleation occurred selectively on the low energy regions. After 90 min, hexagonal prisms had grown upright on these areas. The crystal growth is uniform with a crystal length of about 1 mum and a diameter between 50 and 100 nm. We attribute the selective growth to a combination of crystallographic frustration of the zinc ions on the high energy regions and an accumulation of hydroxide ions on the low energy regions.
pH-tunable gradients of wettability and surface potential
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SM25221J
Spontaneous liquid marble formation on packed porous beds
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SM26529J
Contact angle measurements using the Wilhelmy balance for asymmetrically treated samples
Publisher: Informa UK Limited
Date: 2004
Asymmetric Wetting Hysteresis on Hydrophobic Microstructured Surfaces
Publisher: American Chemical Society (ACS)
Date: 10-03-2009
DOI: 10.1021/LA804246A
Abstract: The wetting behavior of hydrophobic, microstructured surfaces containing arrays of pillars or holes has been investigated. The size of the surface features was fixed (20 microm), while their separation was varied to adjust the area fraction (0-80%). The wettability of structured surfaces for liquids resting in the Cassie state is strongly dependent on the continuity of the solid component. Microstructured square pillars and holes showed distinct, asymmetric wetting hysteresis, consistent with our previous observations on flat, chemically heterogeneous surfaces. Furthermore, clear trends for the magnitude of contact angle hysteresis versus area fraction for the two types of microstructured surfaces are evident. The pinning energy associated with these surface features is estimated.
Electrowetting of Aqueous Solutions of Ionic Liquid in Solid−Liquid−Liquid Systems
Publisher: American Chemical Society (ACS)
Date: 15-04-2010
DOI: 10.1021/JP912115N
Static and Dynamic Electrowetting of an Ionic Liquid in a Solid/Liquid/Liquid System
Publisher: American Chemical Society (ACS)
Date: 27-05-2010
DOI: 10.1021/JA9106397
Abstract: A droplet of an ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, bmim.BF(4)) is immersed in an immiscible liquid (n-hexadecane) and electrowetted on a flat Teflon AF1600-coated ITO electrode. The static contact angle decreases significantly when voltage is applied between the droplet and the electrode: from 145 degrees down to 50 degrees (with DC voltage) and 15 degrees (with AC voltage). The electrowetting curves (contact angle versus voltage) are similar to the ones obtained in other solid/liquid/vapor and solid/liquid/liquid systems: symmetric with respect to zero voltage and correctly described by Young-Lippmann equation below saturation. The reversibility is excellent and contact angle hysteresis is minimal (approximately 2 degrees). The step size used in applying the DC voltage and the polarity of the voltage are unimportant. The saturation contact angle cannot be predicted with the simple zero-interfacial tension theory. Spreading (after applying a DC voltage) and retraction (after switching off the voltage) of the droplet is monitored. The base area of the droplet varies exponentially during wetting (exponential saturation) and dewetting (exponential decay). The characteristic time is 20 ms for spreading and 35 ms for retraction (such asymmetry is not observed with water-glycerol mixtures of a similar viscosity). The spreading kinetics (dynamic contact angle versus contact line speed) can be described by the hydrodynamic model (Voinov's equation) for small contact angles and by the molecular-kinetic model (Blake's equation) for large contact angles. The role of viscous and molecular dissipation follows the scheme outlined by Brochard-Wyart and de Gennes.
Dynamic wetting of a fluoropolymer surface by ionic liquids
Publisher: Royal Society of Chemistry (RSC)
Date: 2011
DOI: 10.1039/C0CP02035D
Abstract: The spontaneous spreading of ionic liquids on a fluoropolymer surface (Teflon AF1600) in air is investigated by high-speed video microscopy. Six ionic liquids (EMIM BF(4), BMIM BF(4), OMIM BF(4), EMIM NTf(2), BMIM NTf(2) and HMIM NTf(2)) are used as probe liquids. The dependence of the dynamic contact angle on contact line velocity is interpreted with a hydrodynamic model and a molecular-kinetic model. The usefulness of the hydrodynamic model is rather limited. There is a good correspondence between the molecular dimensions of the liquids and the physical parameters of the molecular-kinetic model. The viscous and molecular-kinetic contributions to energy dissipation are calculated, revealing that energy is dissipated in the bulk as well as at the contact line during dynamic wetting. There are wide ramifications of these results in areas ranging from lubrication and biology to minerals processing and petroleum recovery.
Wettability of Photoresponsive Titanium Dioxide Surfaces
Publisher: American Chemical Society (ACS)
Date: 20-03-2003
DOI: 10.1021/LA020660C
Capillary Rise with Velocity-Dependent Dynamic Contact Angle
Publisher: American Chemical Society (ACS)
Date: 04-10-2008
DOI: 10.1021/LA801753T
Abstract: The classic description of the rate of capillary rise given by the Washburn equation, which assumes that the contact angle preserves the equilibrium value at all times, has been recently questioned in the light of the known experimental dependence of the dynamic contact angle on the velocity of the contact line. For a number of such proposed functions of velocity for the dynamic contact angle, we analyze the resulting dependences of the contact angle and of the time of rise, respectively, on the height of the capillary rise. By applying our results to the particular cases of a high-viscosity silicone oil and water, respectively, in a glass capillary, we show that, in general, strong similarities arise between the various approaches and the classic theory in what concerns the time dependence of the capillary rise, which explains the lack of consistent experimental evidence for deviations in the rate of capillary rise from the Washburn equation. However, for a strong dependency of the contact angle on the velocity in the range of small velocities, as in the case of water on glass, one of the models predicts significant deviations even for the time dependence of the capillary rise. Moreover, our results show that the time or height dependence of the contact angle during the capillary rise can clearly discriminate between the various models.
Asymmetric Wetting Hysteresis on Chemical Defects
Publisher: American Physical Society (APS)
Date: 13-07-2007
Angle-resolved X-ray photoelectron spectroscopy of the surface of imidazolium ionic liquids
Publisher: Royal Society of Chemistry (RSC)
Date: 2008
DOI: 10.1039/B713584J
Abstract: The surfaces of three imidazolium based ionic liquids with a common anion were studied with angle-resolved X-ray photoelectron spectroscopy (XPS). The room temperature ionic liquids (RTILs): 1-butyl-3-methylimidazolium (bmim), 1-hexyl-3-methylimidazolium (hmim), and 1-octyl-3-methylimidazolium (omim) tetrafluoroborates, were meticulously purified and dried under vacuum. Survey and high-resolution spectra were obtained at different take-off angles (0-84 degrees ), thus increasing the surface sensitivity of the measurement. No impurities were detected and the survey spectra at normal emission (0 degrees ) confirmed the stoichiometric composition of the liquids. However, the spectra at take-off angles of 60, 70, 80 and 84 degrees indicated a higher amount of carbon. High resolution spectra of C1s, at these angles, showed an increased amount of aliphatic carbon when compared to the spectra at normal emission. The longer the side chain (R) of the imidazolium cation (Rmim), the larger was the amount of aliphatic carbon detected. Previous studies with other surface sensitive techniques have yielded contradictory conclusions about the surface orientation of the Rmim. We conclude unequivocally that the alkyl chain of the imidazolium ring of the investigated RTILs is oriented away from the liquid. Our study demonstrates the ability of XPS to probe the structure, along with the composition, of the free liquid surface by comparing signals from different penetration depths.
Evaporation-Driven Flow in Micropillar Arrays: Transport Dynamics and Chemical Analysis under Varied Sample and Ambient Conditions
Publisher: American Chemical Society (ACS)
Date: 03-12-2020
Femtoliter Droplet Handling in Nanofluidic Channels: A Laplace Nanovalve
Publisher: American Chemical Society (ACS)
Date: 07-12-2012
DOI: 10.1021/AC3028905
Abstract: Analytical technologies of ultrasmall volume liquid, in particular femtoliter to attoliter liquid, is essential for single-cell and single-molecule analysis, which is becoming highly important in biology and medical diagnosis. Nanofluidic chips will be a powerful tool to realize chemical processes for such a small volume s le. However, a technical challenge exists in fluidic control, which is femtoliter to attoliter liquid generation in air and handling for further chemical analysis. Integrating mechanical valves fabricated by MEMS (microelectric mechanical systems) technology into nanofluidic channels is difficult. Here, we propose a nonmechanical valve, which is a Laplace nanovalve. For this purpose, a nanopillar array was embedded in a nanochannel using a two-step electron beam lithography and dry-etching process. The nanostructure allowed precise wettability patterning with a resolution below 100 nm, which was difficult by photochemical wettability patterning due to the optical diffraction. The basic principle of the Laplace nanovalve was verified, and a 1.7 fL droplet (water in air) was successfully generated and handled for the first time.
Inferring wettability of heterogeneous surfaces by ToF-SIMS
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.JCIS.2008.01.042
Abstract: Time-of-flight secondary ion mass spectrometry (ToF-SIMS) has been examined as a possible predictive tool for surface wettability. Heterogeneous surfaces were prepared with hydrophilic and hydrophobic regions of known surface coverage using self-assembled monolayers. The surface coverage of each component was then correlated with ToF-SIMS fragmentation of the hydrophobic and hydrophilic surface groups and static contact angle measurements. From these measurements, a clear relationship between the surface wettability and relative intensity of characteristic secondary ions was identified. Moreover, our results for planar surfaces can be extrapolated to predict the wettability of particulate s les for which direct contact angle measurements are not straightforward. The ability to infer particle wettability by ToF-SIMS is well suited to mineral characterization and in particular, the prediction of mineral flotation efficiencies.
Free running droplets on packed powder beds
Publisher: AIP
Date: 2013
DOI: 10.1063/1.4812113
WETTABILITY AND SURFACE ENERGETICS OF ROUGH FLUOROPOLYMER SURFACES
Publisher: Informa UK Limited
Date: 06-2004
Contact Angle Saturation in Electrowetting
Publisher: American Chemical Society (ACS)
Date: 11-03-2005
DOI: 10.1021/JP040478F
Abstract: Electrowetting is the phenomenon of contact angle decrease under the influence of an external voltage applied across the solid/liquid interface. Electrowetting offers an interesting possibility to enhance the wettability of hydrophobic materials without altering the chemical composition of the system and thus could be incorporated in various microfluidic devices. Electrowetting is fundamentally an electrocapillary effect occurring on an insulated solid electrode (hence the change of the solid/liquid interfacial tension with voltage follows Lippmann's equation). A limiting contact angle value larger than zero is achieved even at very large external voltages. Saturation precludes full wetting of the substrate and restricts the magnitude of the capillary force variation. Contact angle saturation has been given various interpretations (e.g., charge trapping, air ionization) but appears to reflect a natural thermodynamic limit rather than being simply a defective property. The limiting value of the contact angle is given by the Young equation when the value of the solid/liquid interfacial tension reaches zero. The model is in excellent agreement with our own results and often gives an adequate description of published data. It also suggests that the saturation limit is determined by the material properties of the system and electrowetting at voltages exceeding this threshold is essentially a nonequilibrium process.
The role of surfactant structure on foam behaviour
Publisher: Elsevier BV
Date: 08-2005
The terminal rise velocity of 10–100 μm diameter bubbles in water
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.JCIS.2008.02.072
Abstract: Single bubbles of very pure N2, He, air and CO2 were formed in a quiescent environment in ultra-clean water, with diameters ranging from 10 to 100 mum. Their terminal rise velocities were measured by high-speed video microscopy. For N2, He and air, excellent agreement with the Hadamard-Rybczynski (H-R) equation was observed, indicating that slip was occurring at the liquid-vapor interface. For CO2 bubbles with diameters less than 60 microm, the terminal rise velocities exceeded those predicted by the H-R equation. This effect was ascribed to the enhanced solubility of CO2 compared with the other gases examined. The presence of a diffusion boundary layer may be responsible for the increased terminal velocity of very small CO2 bubbles.
Dynamics of Wetting from an Experimental Point of View
Publisher: Annual Reviews
Date: 08-2008
DOI: 10.1146/ANNUREV.MATSCI.38.060407.130231
Abstract: This review critically examines the experimental aspects of dynamic wetting, considering extant data for different geometries. Both partial wetting and complete wetting are considered for cases that include droplets, fibers, tubes, and plates. The wetting of porous materials is also considered, along with the new field of micro- and nanofluidics.
Electrowetting of Ionic Liquids on Teflon AF1600 in Ambient Hexadecane
Publisher: Informa UK Limited
Date: 17-05-2012
Contact Line Pinning on Microstructured Surfaces for Liquids in the Wenzel State
Publisher: American Chemical Society (ACS)
Date: 24-08-2009
DOI: 10.1021/LA902296D
Abstract: The wettability of surfaces microstructured with square pillars was studied, where the static advancing contact angle on the planar surface was 72 degrees. We observed elevated advancing angles (up to 140 degrees) on these structures for droplets in the Wenzel state. No air was trapped in the structured surfaces beneath the liquid, ruling out the well-known Lotus leaf effect. Instead, we show that the apparent hydrophobicity is related to contact line pinning at the pillar edges, giving a strong dependence of wetting hysteresis on the fraction of the contact line pinned on pillars. Simulating the contact line pinning on these surfaces showed similar behavior to our measurements, revealing both strong pinning at the edges of the pillars as well as mechanistic details.
Dynamic Electrowetting and Dewetting of Ionic Liquids at a Hydrophobic Solid–Liquid Interface
Publisher: American Chemical Society (ACS)
Date: 14-02-2013
DOI: 10.1021/LA304088T
Abstract: The dynamic electrowetting and dewetting of ionic liquids are investigated with high-speed video microscopy. Five imidazolium-based ionic liquids ([BMIM]BF(4), [BMIM]PF(6), [BMIM]NTf(2), [HMIM]NTf(2), and [OMIM]BF(4)) are used as probe liquids. Droplets of ionic liquids are first spread on an insulated electrode by applying an external voltage (electrowetting) and then allowed to retract (dewetting) when the voltage is switched off. The base area of the droplet varies exponentially during both the electrowetting and retraction processes. The characteristic time increases with the viscosity of the ionic liquid. The electrowetting and retraction kinetics (dynamic contact angle vs contact line speed) can be described by the hydrodynamic or the molecular-kinetic model. Energy dissipation occurs by viscous and molecular routes with a larger proportion of energy dissipated at the three-phase contact line when the liquid meniscus retracts from the solid surface. The outcomes from this research have implications for the design and control of electro-optical imaging systems, microfluidics, and fuel cells.
Preparation of Silica-on-Titania Patterns with a Wettability Contrast
Publisher: American Chemical Society (ACS)
Date: 18-05-2005
DOI: 10.1021/LA046837F
Abstract: The preparation of patterned inorganic surfaces consisting of silica (SiO2) and titania (TiO2) is described. The approach is based on a combination of standard photolithography and plasma-enhanced chemical vapor deposition. Silicon wafers coated with a titania layer (40 nm) were patterned by use of a positive photoresist and then a thin silica layer (10-40 nm) was plasma-deposited. The photoresist was removed by decomposition at 800 degrees C. The inorganic patterned surfaces possessed excellent high-temperature resistance. Since the silica patches were effectively dehydroxylated during the thermal treatment, the patterns consisted of moderately hydrophobic (silica) and hydrophilic (titania) domains with a significant wettability contrast (40 degrees for water). The surface was further hydrophobized with a self-assembled monolayer of fluoroalkylsilane (FAS) and exposed to UV light. The FAS layer was locally oxidized on the TiO2 patches and the wettability contrast was maximized to 120 degrees (the highest possible value on smooth surfaces).
Nanoroughness Impact on Liquid–Liquid Displacement
Publisher: American Chemical Society (ACS)
Date: 10-05-2012
DOI: 10.1021/JP2120274
Related Organisations
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Linkage Projects - Grant ID: LP0667608
Start Date: 2006
End Date: 06-2009
Amount: $225,000.00
Funder: Australian Research Council
View Funded ActivityLinkage - International - Grant ID: LX0562056
Start Date: 10-2005
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Amount: $214,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP1094337
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View Funded ActivityDiscovery Projects - Grant ID: DP110103391
Start Date: 02-2011
End Date: 06-2017
Amount: $250,000.00
Funder: Australian Research Council
View Funded Activity