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Kanduč M, Schneck E, Netz RR. Understanding the "Berg limit": the 65° contact angle as the universal adhesion threshold of biomatter. Phys Chem Chem Phys 2024; 26:713-723. [PMID: 38100091 DOI: 10.1039/d3cp05084j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2024]
Abstract
Surface phenomena in aqueous environments such as long-range hydrophobic attraction, macromolecular adhesion, and even biofouling are predominantly influenced by a fundamental parameter-the water contact angle. The minimal contact angle required for these and related phenomena to occur has been repeatedly reported to be around 65° and is commonly referred to as the "Berg limit." However, the universality of this specific threshold across diverse contexts has remained puzzling. In this perspective article, we aim to rationalize the reoccurrence of this enigmatic contact angle. We show that the relevant scenarios can be effectively conceptualized as three-phase problems involving the surface of interest, water, and a generic oil-like material that is representative of the nonpolar constituents within interacting entities. Our analysis reveals that attraction and adhesion emerge when substrates display an underwater oleophilic character, corresponding to a "hydrophobicity under oil", which occurs for contact angles above approximately 65°. This streamlined view provides valuable insights into macromolecular interactions and holds implications for technological applications.
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Affiliation(s)
- Matej Kanduč
- Department of Theoretical Physics, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia.
| | - Emanuel Schneck
- Department of Physics, Technische Universität Darmstadt, Hochschulstrasse 8, Darmstadt 64289, Germany
| | - Roland R Netz
- Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195, Germany
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2
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Experimental Study of the Influence of the Adsorbate Layer Composition on the Wetting of Different Substrates with Water. ADSORPT SCI TECHNOL 2021. [DOI: 10.1155/2021/6663989] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Wetting is strongly influenced by adsorbate layers, which are omnipresent on surfaces. The influence of the composition and thickness of adsorbate layers on the water contact angle of sessile drops on different substrates was systematically investigated in the present work. Measurements were carried out for gold-sputtered substrates. These new results are compared to results from a previous study, in which corresponding measurements were carried out for technical steel and titanium substrates. In all experiments, different pretreatments of the samples were used to obtain variations of the adsorbate layer. The samples were either exposed to an oil bath or not, and different cleaning agents were used. The analysis of the adsorbate layer was carried out with X-ray photoelectron spectroscopy (XPS). The results for the different substrates reveal that the water contact angle depends mainly on the composition of the adsorbate layer. The substrate has only an indirect influence, as it influences the composition of the adsorbate layer. The thickness of the adsorbate layers was between 1.4 and 14 nm and was large enough to prevent a direct influence of the substrate on the water contact angle. It is shown that using the information on the adsorbate layer composition from XPS and the results for the water contact angle obtained for the gold samples alone, the water contact angles on the steel and titanium samples can be predicted.
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3
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Ditscherlein L, Knüpfer P, Peuker U. The influence of nanobubbles on the interaction forces between alumina particles and ceramic foam filters. POWDER TECHNOL 2019. [DOI: 10.1016/j.powtec.2019.08.077] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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4
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Teh EJ, Ishida N, Skinner WM, Parsons D, Craig VSJ. Forces between zinc sulphide surfaces; amplification of the hydrophobic attraction by surface charge. Phys Chem Chem Phys 2019; 21:20055-20064. [PMID: 31482164 DOI: 10.1039/c9cp02797a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Smooth Zinc Sulphide (ZnS) surfaces were prepared by magnetron sputtering and the interaction forces were measured between them as a function of pH. At the isoelectric point (iep) of pH 7.1 the attractive force was well described by the van der Waals interaction calculated using Lifshitz theory for a layered system. Away from the iep, the forces were fitted using DLVO theory extended to account for surface roughness. At pH 9.8 the surfaces acquire a negative charge and an electrostatic repulsion is evident. Below the iep the surfaces acquire a positive charge leading to electrostatic repulsion. The forces in the range 3.8 < pH < 4.8 show an additional attraction on approach and much greater adhesion than at other pH values. This is attributed to the hydrophobic attraction being amplified by a small degree of charge on the surface as has previously been reported for adhesion measurements. The range of the measured forces is attributed to the long-range orientational order of water (>5 nm).
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Affiliation(s)
- E-Jen Teh
- Department of Applied Mathematics, Research School of Physics, The Australian National University, Mills Rd Acton, Canberra, 2601, Australia.
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5
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Kékicheff P. The long-range attraction between hydrophobic macroscopic surfaces. Adv Colloid Interface Sci 2019; 270:191-215. [PMID: 31277036 DOI: 10.1016/j.cis.2019.06.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 06/04/2019] [Accepted: 06/05/2019] [Indexed: 10/26/2022]
Abstract
Direct measurements of the long-range strongly attractive force observed between macroscopic hydrophobic surfaces across aqueous solutions are reexamined in light of recent experiments and theoretical developments. The focus is on systems in the absence of submicroscopic bubbles (preexistent or induced) to avoid capillary bridging forces. Other possible interferences to the measurements are also eliminated. The force-distance profiles are obtained directly (no contributions from electrical double layer or hydrodynamics) between symmetric identical hydrophobic surfaces, overall charge-neutral, at the thermodynamic equilibrium and in a quenched state. Therefore in the well-defined geometry of crossed-cylinders, sphere-flat, or sphere-sphere, there is no additional interaction to be considered except the ever-present dispersion forces, negligible at large separations. For the three main categories of substrates rendered hydrophobic, namely surfaces obtained with surfactant monolayers physically adsorbed from solution to deposited ones, and substrates coated with a hydrophobizing agent bonded chemically onto the surface, the interaction energy scales as A exp (-2κD)/2κD at large separations, with measured decay lengths in accord with theoretical predictions, simply being half the Debye screening length, κ-1/2, at least in non vanishing electrolyte. Taken together with the prefactor A scaling as the ionic strength, the interaction energy is demonstrated to have an electrostatic origin in all the systems. Thanks to our recent SFAX coupling force measurements with x-ray solution scattering under controlled nano-confinement, the microstructuration of the adsorbed film emerges as an essential feature in the molecular mechanism for explaining the observed attraction of larger magnitude than dispersion forces. The adsorption of pairs of positive and negative ions on small islands along the interface, the fluctuation of the surface charge density around a zero mean-value with desorption into or adsorption from the electrolyte solution, the correlations in the local surface ion concentrations along the surfaces, the redistribution of counterions upon intersurface variation, all contribute and are tuned finely by the inhomogeneities and defects present in the hydrophobic layers. It appears that the magnitude of the interacting energy can be described by a single master curve encompassing all the systems.
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Lam J, Lutsko JF. Solvent-mediated interactions between nanostructures: From water to Lennard-Jones liquid. J Chem Phys 2018; 149:134703. [PMID: 30292194 DOI: 10.1063/1.5037571] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Solvent-mediated interactions emerge from complex mechanisms that depend on the solute structure, its wetting properties, and the nature of the liquid. While numerous studies have focused on the first two influences, here, we compare the results from water and Lennard-Jones liquid in order to reveal to what extent solvent-mediated interactions are universal with respect to the nature of the liquid. Besides the influence of the liquid, the results were obtained with classical density functional theory and brute-force molecular dynamics simulations which allow us to contrast these two numerical techniques.
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Affiliation(s)
- Julien Lam
- Center for Nonlinear Phenomena and Complex Systems, Universite Libre de Bruxelles, Code Postal 231, Boulevard du Triomphe, 1050 Brussels, Belgium
| | - James F Lutsko
- Center for Nonlinear Phenomena and Complex Systems, Universite Libre de Bruxelles, Code Postal 231, Boulevard du Triomphe, 1050 Brussels, Belgium
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7
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Ishida N, Matsuo K, Imamura K, Craig VSJ. Hydrophobic Attraction Measured between Asymmetric Hydrophobic Surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3588-3596. [PMID: 29489375 DOI: 10.1021/acs.langmuir.7b04246] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interaction forces between silica surfaces modified to different degrees of hydrophobicity were measured using colloidal probe atomic force microscopy (AFM). A highly hydrophobic silica particle was prepared with octadecyltrichlorosilane (OTS), and the interaction forces were measured against silica substrates modified to produce surfaces of varying hydrophobicity. The interaction forces between the highly hydrophobic particle and a completely hydrophilic silicon wafer surface fitted well to the DLVO theory, indicating that no additional (non-DLVO) forces act between the surfaces. When the silicon wafer surface was treated to produce a contact angle of water on surface of 40°, an additional attractive force that is longer ranged than the van der Waals force was observed between the surfaces. The range and magnitude of the attractive force increase with the contact angle of water on the substrate. Beyond the effect on the contact angle, the hydrocarbon chain length and the terminal groups of hydrophobic layer on the substrate only have a minor effect on the magnitude of the force, even when the substrate is terminated with polar carboxyl groups, provided the hydrophobicity of the other surface is high.
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Affiliation(s)
- Naoyuki Ishida
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 , Japan
| | - Kohei Matsuo
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 , Japan
| | - Koreyoshi Imamura
- Division of Applied Chemistry, Graduate School of Natural Science and Technology , Okayama University , 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530 , Japan
| | - Vincent S J Craig
- Department of Applied Mathematics, Research School of Physics and Engineering , The Australian National University , Canberra ACT 2601 , Australia
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Eom N, Parsons DF, Craig VSJ. Measurement of long range attractive forces between hydrophobic surfaces produced by vapor phase adsorption of palmitic acid. SOFT MATTER 2017; 13:8910-8921. [PMID: 29143037 DOI: 10.1039/c7sm01563a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Extensive research into the surface forces between hydrophobic surfaces has produced experimentally measured interaction forces that vary widely in range and in magnitude. This variability is attributed to interference from surface nanobubbles and the nature of the hydrophobic surface. Whilst the effects of nanobubbles are now recognised and can be addressed, the precise nature of the surface remains a confounding factor in measurements between hydrophobic surfaces. Here we show that a monolayer coating with hydrophobic properties is formed by exposing metal oxide surfaces to palmitic acid vapour. Surface forces measured between these smooth hydrophobic surfaces exhibited an exponential attraction. Neither patchy surface charges, nor surface nanobubbles could explain the measured forces. However, the observed interaction may be explained by the interaction of a single patch of bilayered palmitic acid molecules interacting with an exposed patch of the hafnia surface. Such an interaction is consistent with the observed exponential nature of the attraction and the agreement between the measured decay of the exponential attraction with the Debye length of the solution.
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Affiliation(s)
- Namsoon Eom
- Department of Applied Mathematics, Research School of Physics and Engineering, Australian National University, Canberra, ACT 2601, Australia.
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9
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Arai N, Koishi T, Ebisuzaki T. Theory of nanobubble formation and induced force in nanochannels. Phys Rev E 2017; 96:042802. [PMID: 29347539 DOI: 10.1103/physreve.96.042802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2016] [Indexed: 06/07/2023]
Abstract
This paper presents a fundamental theory of nanobubble formation and induced force in confined nanochannels. It is shown that nanobubble formation between hydrophobic plates can be predicted from their surface tension and geometry, with estimated values for the surface free energy and the force acting on the plates in good agreement with the results of molecular dynamics simulation and experimentation. When a bubble is formed between two plates, vertical attractive force and horizontal retract force due to the shifted plates are applied to the plates. The net force exerted on the plates is not dependent on the distance between them. The short-range force between hydrophobic surfaces due to hydrophobic interaction appears to correspond to the force estimated by our theory. We compared between experimental and theoretical values for the binding energy of a molecular motor system to validate our theory. The tendency that the binding energy increases as the size of the protein increases is consistent with the theory.
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Affiliation(s)
- Noriyoshi Arai
- Department of Mechanical Engineering, Kindai University, Osaka 57808522, Japan
| | - Takahiro Koishi
- Department of Applied Physics, University of Fukui, Fukui 910-8507, Japan
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10
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Chen Q, Stricek I, Gray MR, Liu Q. Influence of hydrophobicity distribution of particle mixtures on emulsion stabilization. J Colloid Interface Sci 2017; 491:179-189. [PMID: 28027467 DOI: 10.1016/j.jcis.2016.12.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 12/18/2016] [Accepted: 12/19/2016] [Indexed: 10/20/2022]
Abstract
Whilst emulsions stabilized by uniform particles are well established, the emulsification behavior of heterogeneous mixtures of particles with varying hydrophobicity is rarely examined. Consequently, the influence of the distribution of particle hydrophobicity on oil-water emulsion stabilization is poorly understood. In the present work, the wettability of the bitumen froth fine solids from Alberta oil sands was studied by film flotation and toluene-water emulsification tests, before and after a hydrothermal treatment at 300-420°C. This approach provided a series of populations of particles with different distributions of hydrophobicity. The initial fine particles in the bitumen froth had a critical surface tension ranging from 26 to 56mN/m, with a mean value of 39mN/m. Hydrothermal treatment at 300-420°C progressively shifted the hydrophobicity distribution of the fine particles, resulting in a lower mean critical surface tension and a narrower critical surface tension range. The emulsifying capacity of the fine particle mixtures, as indicated by the volume of the produced toluene-water emulsions, was unrelated to the mean critical surface tension. Instead, emulsification depended on the proportion of a specific sub-fraction of particles with a critical surface tension of 27-30mN/m. This sub-fraction of particles, with intermediate hydrophobicity, dominated the emulsification behavior of the particle mixtures.
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Affiliation(s)
- Qiang Chen
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Igor Stricek
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Murray R Gray
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Qi Liu
- Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada.
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11
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Recent experimental advances on hydrophobic interactions at solid/water and fluid/water interfaces. Biointerphases 2016; 11:018903. [DOI: 10.1116/1.4937465] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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12
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Tabor RF, Grieser F, Dagastine RR, Chan DYC. The hydrophobic force: measurements and methods. Phys Chem Chem Phys 2014; 16:18065-75. [DOI: 10.1039/c4cp01410c] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The hydrophobic force describes the attraction between water-hating molecules (and surfaces) that draws them together, causing aggregation, phase separation, protein folding and many other inherent physical phenomena.
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Affiliation(s)
- Rico F. Tabor
- School of Chemistry
- Monash University
- Clayton, Australia
| | - Franz Grieser
- Particulate Fluids Processing Centre
- The University of Melbourne
- Parkville 3010, Australia
- School of Chemistry
- The University of Melbourne
| | - Raymond R. Dagastine
- Particulate Fluids Processing Centre
- The University of Melbourne
- Parkville 3010, Australia
- Department of Chemical and Biomolecular Engineering
- The University of Melbourne
| | - Derek Y. C. Chan
- Particulate Fluids Processing Centre
- The University of Melbourne
- Parkville 3010, Australia
- Department of Mathematics and Statistics
- The University of Melbourne
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13
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AFM forces between mica and polystyrene surfaces in aqueous electrolyte solutions with and without gas bubbles. J Colloid Interface Sci 2013; 410:188-94. [DOI: 10.1016/j.jcis.2013.08.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 07/31/2013] [Accepted: 08/02/2013] [Indexed: 11/21/2022]
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14
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Wu CC, Chen MY, Sailor MJ. Differential adsorption of small molecules in spatially functionalized porous silicon nanostructures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:11802-11808. [PMID: 23965031 DOI: 10.1021/la402261v] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
An experimental approach to rapidly quantify the relative affinity of a small molecule analyte for two different surfaces is described. The method uses optical measurements of high surface area porous Si thin films that contain two spatially distinct surface chemistries. The chemistries are placed on the walls of the ∼10 nm diameter pores of the porous Si film by means of microdroplet patterning, where a chemical resist is drop-coated on the porous Si sample to define distinct regions across the plane of the chip. In this work, the two chemistries consist of a hydrophilic silicon oxide surface and a hydrophobic methyl-terminated silicon surface. Detection is achieved by simultaneous optical reflectance measurements of both regions, where the reflectance spectrum contains a convolution of the Fabry-Pérot interference spectrum of both the oxide and the methyl-grafted layers. The differential partitioning of a test analyte (2-acetoxybenzoic acid or diphenyl ether) from aqueous solution is determined from the Fourier transform of the optical interference spectrum. The approach is rapid and nondestructive, and it can be performed on a small sample volume as a means to quantify the partition behavior of small molecules.
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Affiliation(s)
- Chia-Chen Wu
- Materials Science and Engineering, ‡Department of Bioengineering, §Department of Chemistry and Biochemistry, University of California, San Diego , 9500 Gilman Drive, La Jolla, California 92093, United States
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15
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Nugroho RWN, Pettersson T, Odelius K, Höglund A, Albertsson AC. Force interactions of nonagglomerating polylactide particles obtained through covalent surface grafting with hydrophilic polymers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:8873-8881. [PMID: 23799799 DOI: 10.1021/la401076m] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Nonagglomerating polylactide (PLA) particles with various interaction forces were designed by covalent photografting. PLA particles were surface grafted with hydrophilic poly(acrylic acid) (PAA) or poly(acrylamide) (PAAm), and force interactions were determined using colloidal probe atomic force microscopy. Long-range repulsive interactions were detected in the hydrophilic/hydrophilic systems and in the hydrophobic/hydrophilic PLA/PLA-g-PAAm system. In contrast, attractive interactions were observed in the hydrophobic PLA/PLA and in the hydrophobic/hydrophilic PLA/PLA-g-PAA systems. AFM was also used in the tapping mode to determine the surface roughness of both neat and surface-grafted PLA film substrates. The imaging was performed in the dry state as well as in salt solutions of different concentrations. Differences in surface roughness were identified as conformational changes induced by the altered Debye screening length. To understand the origin of the repulsive force, the AFM force profiles were compared to the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory and the Alexander de Gennes (AdG) model. The steric repulsion provided by the different grafted hydrophilic polymers is a useful tool to inhibit agglomeration of polymeric particles. This is a key aspect in many applications of polymer particles, for example in drug delivery.
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Affiliation(s)
- Robertus Wahyu N Nugroho
- Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Stockholm, Sweden
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16
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Fontani G, Gaspari R, Spencer ND, Passerone D, Crockett R. Adsorption and friction behavior of amphiphilic polymers on hydrophobic surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:4760-4771. [PMID: 23509926 DOI: 10.1021/la400263r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The ability of amphiphilic polymers to self-assemble and form a gel or gel-like layer has been investigated by means of both experimental and theoretical studies on alkylated derivatives of poly(acrylic acid). Experiments were performed to determine the relationship between amphiphilic polymer chemistry, structure, water retention, and friction in the presence of hydrophobic substrates. The results indicate that the amphiphilic polymer forms a water-enriched, friction-reducing adsorbed layer on hydrophobic surfaces. The shear moduli and viscosities of the adsorbed layers, as determined by fitting the Voigt model to QCM-D data, were consistent with the presence of a gel. Computational studies on HPAA-12 were performed and are consistent with the presence of adsorbed conformations, in which the lowest free energy in the model corresponded to a partially adsorbed molecule, with a small fraction of hydrophobic side chains being compelled, for configurational reasons, to point into the bulk water. This would support the possibility of the formation of either a gel-like layer or surface aggregation. However, because the adsorption experiments showed no evidence of aggregation, this strongly suggests the formation of a gel.
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Affiliation(s)
- Giacomo Fontani
- Swiss Federal Laboratories for Materials Science and Technology, Empa, Duebendorf, Switzerland
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17
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Ishida N, Kusaka Y, Ushijima H. Hydrophobic attraction between silanated silica surfaces in the absence of bridging bubbles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:13952-13959. [PMID: 22931235 DOI: 10.1021/la303037d] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The interaction forces between silanated silica surfaces on which there were neither nanobubbles nor a gas phase were measured using colloidal probe atomic force microscopy (AFM). To obtain hydrophobic surfaces without attached nanobubbles, an aqueous solution was introduced between the surfaces after an exchange process involving several solvents. In the approaching force curves obtained, an attractive force was observed from a distance of 10-25 nm, indicating the existence of an additional attractive force stronger than the van der Waals attraction. In the retracting force curves, a strong adhesion force was observed, and the value of this force was comparable to that of the capillary bridging force. The data clearly showed that although the bridging of nanobubbles is responsible for long-range hydrophobic attraction, there also exists an additional attractive force larger than the van der Waals attraction between hydrophobic surfaces without nanobubbles. Both the ionic strength and the temperature of the solution had little influence on the force. The possible origin of the force is discussed on the basis of the obtained results.
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Affiliation(s)
- Naoyuki Ishida
- Flexible Electronics Research Center, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Japan.
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18
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Hansson PM, Hormozan Y, Brandner BD, Linnros J, Claesson PM, Swerin A, Schoelkopf J, Gane PAC, Thormann E. Effect of surface depressions on wetting and interactions between hydrophobic pore array surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:11121-11130. [PMID: 22769744 DOI: 10.1021/la302036d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The surface structure is known to significantly affect the long-range capillary forces between hydrophobic surfaces in aqueous solutions. It is, however, not clear how small depressions in the surface will affect the interaction. To clarify this, we have used the AFM colloidal probe technique to measure interactions between hydrophobic microstructured pore array surfaces and a hydrophobic colloidal probe. The pore array surfaces were designed to display two different pore spacings, 1.4 and 4.0 μm, each with four different pore depths ranging from 0.2 to 12.0 μm. Water contact angles measured on the pore array surfaces are lower than expected from the Cassie-Baxter and Wenzel models and not affected by the pore depth. This suggests that the position of the three-phase contact line, and not the interactions underneath the droplet, determines the contact angle. Confocal Raman microscopy was used to investigate whether water penetrates into the pores. This is of importance for capillary forces where both the movement of the three-phase contact line and the situation at the solid/liquid interface influence the stability of bridging cavities. By analyzing the shape of the force curves, we distinguish whether the cavity between the probe and the surfaces was formed on a flat part of the surface or in close proximity to a pore. The pore depth and pore spacing were both found to statistically influence the distance at which cavities form as surfaces approach each other and the distance at which cavities rupture during retraction.
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Affiliation(s)
- Petra M Hansson
- YKI, Ytkemiska Institutet AB/Institute for Surface Chemistry, Stockholm, Sweden
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Hansson PM, Swerin A, Schoelkopf J, Gane PAC, Thormann E. Influence of surface topography on the interactions between nanostructured hydrophobic surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:8026-34. [PMID: 22554262 DOI: 10.1021/la300628m] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Nanostructured particle coated surfaces, with hydrophobized particles arranged in close to hexagonal order and of specific diameters ranging from 30 nm up to 800 nm, were prepared by Langmuir-Blodgett deposition followed by silanization. These surfaces have been used to study interactions between hydrophobic surfaces and a hydrophobic probe using the AFM colloidal probe technique. The different particle coated surfaces exhibit similar water contact angles, independent of particle size, which facilitates studies of how the roughness length scale affects capillary forces (previously often referred to as "hydrophobic interactions") in aqueous solutions. For surfaces with smaller particles (diameter < 200 nm), an increase in roughness length scale is accompanied by a decrease in adhesion force and bubble rupture distance. It is suggested that this is caused by energy barriers that prevent the motion of the three-phase (vapor/liquid/solid) line over the surface features, which counteracts capillary growth. Some of the measured force curves display extremely long-range interaction behavior with rupture distances of several micrometers and capillary growth with an increase in volume during retraction. This is thought to be a consequence of nanobubbles resting on top of the surface features and an influx of air from the crevices between the particles on the surface.
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Affiliation(s)
- Petra M Hansson
- YKI, Ytkemiska Institutet AB/Institute for Surface Chemistry, Stockholm, Sweden
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20
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Layfield JP, Troya D. Molecular Simulations of the Structure and Dynamics of Water Confined between Alkanethiol Self-Assembled Monolayer Plates. J Phys Chem B 2011; 115:4662-70. [DOI: 10.1021/jp1120178] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Joshua P. Layfield
- Department of Chemistry, Virginia Tech, 107 Davidson Hall, Blacksburg, Virginia 24061-0212, United States
| | - Diego Troya
- Department of Chemistry, Virginia Tech, 107 Davidson Hall, Blacksburg, Virginia 24061-0212, United States
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Hammer MU, Anderson TH, Chaimovich A, Scott Shell M, Israelachvili J. The search for the hydrophobic force law. Faraday Discuss 2010; 146:299-401. [PMID: 21043428 PMCID: PMC3058852 DOI: 10.1039/b926184b] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
After nearly 30 years of research on the hydrophobic interaction, the search for the hydrophobic force law is still continuing. Indeed, there are more questions than answers, and the experimental data are often quite different for nominally similar conditions, as well as, apparently, for nano-, micro-, and macroscopic surfaces. This has led to the conclusion that the experimentally observed force-distance relationships are either a combination of different 'fundamental' interactions, or that the hydrophobic force-law, if there is one, is complex--depending on numerous parameters. The only unexpectedly strong attractive force measured in all experiments so far has a range of D approximately 100-200 angstroms, increasing roughly exponentially down to approximately 10-20 angstroms and then more steeply down to adhesive contact at D = 0 or, for power-law potentials, effectively at D approximately 2 angstroms. The measured forces in this regime (100-200 angstroms) and especially the adhesive forces are much stronger, and have a different distance-dependence from the continuum VDW force (Lifshitz theory) for non-conducting dielectric media. We suggest a three-regime force-law for the forces observed between hydrophobic surfaces: In the first, from 100-200 angstroms to thousands of angstroms, the dominating force is created by complementary electrostatic domains or patches on the apposing surfaces and/or bridging vapour cavities; a 'pure' but still not well-understood 'long-range hydrophobic force' dominates the second regime from approximately 150 to approximately 15 angstroms, possibly due to an enhanced Hamaker constant associated with the 'proton-hopping' polarizability of water; while below approximately 10-15 anstroms to contact there is another 'pure short-range hydrophobic force' related to water structuring effects associated with surface-induced changes in the orientation and/or density of water molecules and H-bonds at the water-hydrophobic interface. We present recent SFA and other experimental results, as well as a simplified model for water based on a spherically-symmetric potential that is able to capture some basic features of hydrophobic association. Such a model may be useful for theoretical studies of the HI over the broad range of scales observed in SFA experiments.
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22
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Wallqvist V, Claesson PM, Swerin A, Ostlund C, Schoelkopf J, Gane PAC. Influence of surface topography on adhesive and long-range capillary forces between hydrophobic surfaces in water. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:9197-9207. [PMID: 19719221 DOI: 10.1021/la900759e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We report on the interactions between a hydrophobic probe particle and surfaces with nanoscopic surface features. These surfaces have been prepared by spin-coating of nanoparticles and by polishing. The surface topography was characterized by AFM, using the methods of high-resolution imaging, low-resolution imaging using the probe particle, and by the rolling ball method. The spin-coated surfaces can be characterized as nanostructured due to the high density of nanoparticles that on a short length scale provides a regular pattern of crevices and hills. On these surfaces a larger waviness is also distinguished. In contrast, the polished surfaces display sharp nanoscopic peaks and hardly any crevices. In all cases the dominant force at short separations was found to be a capillary attraction due to the formation of an air/vapor condensate. Our data show that the large-scale waviness of the surface does not significantly influence the range and magnitude of the capillary attraction, but large local variations in these quantities are found. The large variation in adhesion force corresponds to a small variation in local contact angle of the capillary condensate at the surfaces. The report discusses how the nature of the surface topographical features influences the capillary attraction by influencing the local contact angle and by pinning of the three-phase contact line. The effect is clearly dependent on whether the surface features exist in the form of crevices or as extending ridges.
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Affiliation(s)
- Viveca Wallqvist
- YKI, Ytkemiska Institutet AB/Institute for Surface Chemistry, Box 5607, SE-114 86 Stockholm, Sweden.
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23
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Wang J, Yoon RH. AFM forces measured between gold surfaces coated with self-assembled monolayers of 1-hexadecanethiol. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:7889-7896. [PMID: 18576609 DOI: 10.1021/la800276r] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
An atomic force microscope (AFM) was used to measure the forces between gold surfaces with and without hydrophobizing them by the self-assembly of 1-hexadecanethiol. The forces measured between bare gold surfaces were fitted to the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory with a Hamaker constant of 1.2 x 10 (-20) J, which was close to the value determined using the methylene iodide contact angle method but was lower than that calculated using the Lifshitz theory. When the surfaces were hydrophobized in a 0.01 mM thiol-in-ethanol solution for 10 min, the measured forces exhibited a long-range force with a decay length of 35 nm. Despite its high water contact angle (105 degrees ), the force curve was smooth and exhibited no steps. When the surfaces were hydrophobized in a 1 mM thiol solution for longer than 6 h, however, the force curves exhibited steps, indicating that the long-range attractions were caused by bridging bubbles. When the measurements were conducted after washing the substrates with organic solvents, the steps disappeared and long-range attractive forces appeared. In the presence of ethanol, the water contact angle decreased to below 90 degrees , the attraction became weaker, and the force curves became smooth. On the basis of the results obtained in the present work, possible mechanisms for the long-range attractions are discussed.
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Affiliation(s)
- Jialin Wang
- Center for Advanced Separation Technologies, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA
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24
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Fang KC, Weng CI. Molecular dynamics simulations of structural features and diffusion properties of fullerene-in-water suspensions. J Colloid Interface Sci 2008; 318:188-94. [DOI: 10.1016/j.jcis.2007.10.058] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2007] [Revised: 10/17/2007] [Accepted: 10/25/2007] [Indexed: 11/17/2022]
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25
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Abstract
Results of current theoretical methods for the calculation of contact angles on low-energy surfaces as functions of composition of solution and surface properties are reviewed.
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Affiliation(s)
- N V Churaev
- Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Leninskii pr. 31, Moscow, 119991, Russian Federation
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26
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Subramanian S, Sampath S. Dewetting phenomenon: Interfacial water structure at well-organized alkanethiol-modified gold–aqueous interface. J Colloid Interface Sci 2007; 313:64-71. [PMID: 17531999 DOI: 10.1016/j.jcis.2007.04.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2007] [Revised: 04/10/2007] [Accepted: 04/10/2007] [Indexed: 11/16/2022]
Abstract
The interfacial properties at well-ordered short-chain alkanethiol monolayer-aqueous interfaces are probed to understand the water structure near a hydrophobic surface. Monolayers of hexanethiol on highly oriented gold substrates have been prepared by various methods such as adsorption from alcoholic solution of the thiol, adsorption from neat thiol, and potential-controlled adsorption. The compactness and crystallinity of the monolayer have been probed using reflection-absorption infrared spectroscopy (RAIRS), atomic force microscopy (AFM), quartz crystal microbalance (QCM), and electrochemical techniques. The presence of a thin layer of solvent with reduced density/dielectric constant (termed "drying transition") close to the methyl groups is identified. This is based on reduced interfacial capacitance observed in the presence of an aqueous electrolyte solution as compared to the expected value for a well-ordered monolayer-aqueous interface. Atomic force microscopy allows the determination of the variation in the dielectric constant of the solvent medium as a function of distance from the monolayer head group. The thickness of the transition layer (interphase) is found to be approximately 2 nm. The phenomenon of drying transition is not unique to water; preliminary studies indicate that formamide, which has a two-dimensional hydrogen-bonded network, shows similar characteristics.
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Affiliation(s)
- S Subramanian
- Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
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27
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Zhang J, Yoon RH, Eriksson JC. AFM surface force measurements conducted with silica in CnTACl solutions: Effect of chain length on hydrophobic force. Colloids Surf A Physicochem Eng Asp 2007. [DOI: 10.1016/j.colsurfa.2007.01.048] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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28
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Tareste D, Pincet F, Lebeau L, Perez E. Hydrophobic forces and hydrogen bonds in the adhesion between retinoid-coated surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:3225-9. [PMID: 17266339 DOI: 10.1021/la0629779] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Interactions between hydrophobic chains of lipid monolayers and interactions between hydrophilic headgroups of lipid bilayers (with or without a molecular recognition step) are now well documented, especially for commonly used lipids. Here, we report force measurements between a new class of fluorinated lipid layers whose headgroups (synthetic ligands of retinoid receptors) display a very unusual polar/apolar character and can interact via a combination of hydrophobic forces and hydrogen bonds. Although these two interactions produce adhesion and are therefore not easily distinguishable, we show that it is possible to extract both contributions unambiguously. Experiments are performed both in pure water, where the adhesion is a combination of hydrophobic forces and hydrogen bonds, and in Tris buffer, where the hydrophobic effect is the dominant short-range attractive force. The contribution of hydrophobic forces scaled down to molecular interactions is deduced from force versus distance profiles, and the same value is found independently in pure water and Tris buffer, about 1 kBT. We also show that retinoid lipid layers attract each other through a very long-range (100 nm) exponential force, which is insensitive to the pH and the salinity. The origin of this long-range attraction is discussed on the basis of previously proposed mechanisms.
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Affiliation(s)
- David Tareste
- Laboratoire de Physique Statistique de l'Ecole Normale Supérieure, UMR 8550, CNRS, Universités Paris 6 et Paris 7, 24 rue Lhomond, 75005 Paris, France
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29
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Interaction of calcium dioleate collector colloids with calcite and fluorite surfaces as revealed by AFM force measurements and molecular dynamics simulation. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.minpro.2006.08.006] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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30
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Meyer EE, Rosenberg KJ, Israelachvili J. Recent progress in understanding hydrophobic interactions. Proc Natl Acad Sci U S A 2006; 103:15739-46. [PMID: 17023540 PMCID: PMC1635073 DOI: 10.1073/pnas.0606422103] [Citation(s) in RCA: 572] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We present here a brief review of direct force measurements between hydrophobic surfaces in aqueous solutions. For almost 70 years, researchers have attempted to understand the hydrophobic effect (the low solubility of hydrophobic solutes in water) and the hydrophobic interaction or force (the unusually strong attraction of hydrophobic surfaces and groups in water). After many years of research into how hydrophobic interactions affect the thermodynamic properties of processes such as micelle formation (self-assembly) and protein folding, the results of direct force measurements between macroscopic surfaces began to appear in the 1980s. Reported ranges of the attraction between variously prepared hydrophobic surfaces in water grew from the initially reported value of 80-100 Angstrom to values as large as 3,000 Angstrom. Recent improved surface preparation techniques and the combination of surface force apparatus measurements with atomic force microscopy imaging have made it possible to explain the long-range part of this interaction (at separations >200 Angstrom) that is observed between certain surfaces. We tentatively conclude that only the short-range part of the attraction (<100 Angstrom) represents the true hydrophobic interaction, although a quantitative explanation for this interaction will require additional research. Although our force-measuring technique did not allow collection of reliable data at separations <10 Angstrom, it is clear that some stronger force must act in this regime if the measured interaction energy curve is to extrapolate to the measured adhesion energy as the surface separation approaches zero (i.e., as the surfaces come into molecular contact).
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Affiliation(s)
| | | | - Jacob Israelachvili
- Chemical Engineering, University of California, Santa Barbara, CA 93106
- To whom correspondence should be addressed. E-mail:
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31
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Churaev NV. Aqueous wetting films in contact with a solid phase. Adv Colloid Interface Sci 2005; 114-115:3-7. [PMID: 15904889 DOI: 10.1016/j.cis.2004.04.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2004] [Accepted: 04/14/2004] [Indexed: 11/16/2022]
Affiliation(s)
- N V Churaev
- Institute of Physical Chemistry of the Russian Academy of Science, 119991, Moscow, Leninsky Prospect 31, Russia.
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32
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Fa K, Nguyen AV, Miller JD. Hydrophobic Attraction As Revealed by AFM Force Measurements and Molecular Dynamics Simulation. J Phys Chem B 2005; 109:13112-8. [PMID: 16852631 DOI: 10.1021/jp0445526] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Spherical calcium dioleate particles ( approximately 10 mum in diameter) were used as AFM (atomic force microscope) probes to measure interaction forces of the collector colloid with calcite and fluorite surfaces. The attractive AFM force between the calcium dioleate sphere and the fluorite surface is strong and has a longer range than the DLVO (Derjaguin-Landau-Verwey-Overbeek) prediction. The AFM force between the calcium dioleate sphere and the mineral surfaces does not agree with the DLVO prediction. Consideration of non-DLVO forces, including the attractive hydrophobic force and the repulsive hydration force, was necessary to explain the experimental results. The non-DLVO interactions considered were justified by the different interfacial water structures at calcite- and fluorite-water interfaces as revealed by the numerical computation experiments with molecular dynamics simulation.
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Affiliation(s)
- Keqing Fa
- Department of Metallurgical Engineering, University of Utah, 135 South 1460 East, Salt Lake City, Utah 84112, USA.
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33
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Meyer EE, Lin Q, Israelachvili JN. Effects of dissolved gas on the hydrophobic attraction between surfactant-coated surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:256-259. [PMID: 15620311 DOI: 10.1021/la048318i] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The effect of dissolved gas on the hydrophobic attraction between double-chained surfactant monolayers physisorbed on mica has been studied using a surface forces apparatus (SFA). Distance vs time data were obtained over the full distance regime from D approximately 1000 A down to contact using the dynamic SFA method. Removal of dissolved gas was seen to reduce the range of the attraction while the short-range attraction (under approximately 250 A) remained unchanged. The implications for the possibility of two distinct force regimes in the interactions between hydrophobic surfaces are discussed.
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Affiliation(s)
- Emily E Meyer
- Departments of Physics and Chemical Engineering, University of California at Santa Barbara, CA 93106, USA
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34
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Lin Q, Meyer EE, Tadmor M, Israelachvili JN, Kuhl TL. Measurement of the long- and short-range hydrophobic attraction between surfactant-coated surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:251-255. [PMID: 15620310 DOI: 10.1021/la048317q] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
We have measured the attractive long-range 'hydrophobic' forces in water between double-chained surfactant monolayers physisorbed on mica. We used both normal and high-speed video cameras to follow the dynamics and possible rate-dependence of force-distance profiles in the distance regime from 1000 A to adhesive contact, including the short-distance regime below 100 A-the regime of greatest biological interest. We find that the hydrophobic interaction follows a double-exponential function down to separations of approximately 50 A, after which point the attractive force appears to become considerably stronger.
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Affiliation(s)
- Qi Lin
- Department of Chemical Engineering, University of California at Santa Barbara, CA 93106, USA
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36
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37
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Abbasian A, Ghaffarian SR, Mohammadi N, Fallahi D. Sensitivity of surface free energy analysis methods to the contact angle changes attributed to the thickness effect in thin films. J Appl Polym Sci 2004. [DOI: 10.1002/app.20672] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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38
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Abstract
This review links together for the first time both the practicalities of force measurement and the work carried out to date on force detection between polymeric surfaces in liquids using the atomic force microscope (AFM). Also included is some of the recent work that has been carried out between surfactant surfaces and biologically coated surfaces with the AFM. The emphasis in this review is on the practical issues involved with force measurement between these types of surfaces, and the similarities and irregularities between the observed types of forces measured. Comparison is made between AFM and surface force apparatus (SFA) measurements, as there is a much longer history of work with the latter. Results indicate that forces between the surfaces reviewed here are a complicated mixture of steric-type repulsion, conformational behaviour on separation and long-range attraction, which is often ascribed to 'hydrophobic' forces. The origin of this latter force remains uncertain, despite its almost ubiquitous appearance in force measurements with these types of surfaces.
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Affiliation(s)
- C S Hodges
- Department of Chemical Engineering University of Leeds, UK.
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39
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Christenson HK, Claesson PM. Direct measurements of the force between hydrophobic surfaces in water. Adv Colloid Interface Sci 2001. [DOI: 10.1016/s0001-8686(00)00036-1] [Citation(s) in RCA: 343] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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40
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Škvarla J. Hydrophobic interaction between macroscopic and microscopic surfaces. Unification using surface thermodynamics. Adv Colloid Interface Sci 2001. [DOI: 10.1016/s0001-8686(99)00035-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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41
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Aston D, Berg JC. Long-range attraction between silanated silica materials studied by an electrolyte titration with atomic force microscopy. Colloids Surf A Physicochem Eng Asp 2000. [DOI: 10.1016/s0927-7757(99)00310-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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42
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Boehnke U, Remmler T, Motschmann H, Wurlitzer S, Hauwede J, Fischer TM. Partial Air Wetting on Solvophobic Surfaces in Polar Liquids. J Colloid Interface Sci 1999; 211:243-251. [PMID: 10049541 DOI: 10.1006/jcis.1998.5987] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The properties of solvophobic surfaces in polar liquids are studied by sedimentation experiments as well as by force measurements using a scanning force microscope (SFM). Depending on whether the polar liquid contacts the solvophobic surface under normal air pressure or under vacuum the experimental results are different. Sedimentation velocities of vacuum-contacted solvophobic surfaces are similar to those of solvophilic vacuum- or air-contacted ones. However, for the air-contacted solvophobic surfaces there is a slip boundary condition of the hydrodynamic flow causing a change of the sedimentation velocity of about 20%, and a long-range attraction varying with the polarity of the liquid molecule is observed between them. These effects can be explained by an incomplete air dewetting of the solvophobic surface when brought into contact with the polar liquid at normal air pressure. Copyright 1999 Academic Press.
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Affiliation(s)
- U Boehnke
- Faculty of Physics and Geosciences, University of Leipzig, Linnéstrasse 5, Leipzig, 04103, Germany
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44
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Hato M, Minamikawa H, Seguer JB. Stereochemistry-Dependent Self-Assembly in Synthetic Glycolipid/Water Systems: The Aqueous Phase Structure of 1,3-Di-O-dodecyl-2-(β-maltoheptaosyl)glycerol. J Phys Chem B 1998. [DOI: 10.1021/jp9733328] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Masakatsu Hato
- Surface Engineering Laboratory, National Institute of Materials and Chemical Research, 1−1, Higashi, Tsukuba, Ibaraki-305-8565, Japan
| | - Hiroyuki Minamikawa
- Surface Engineering Laboratory, National Institute of Materials and Chemical Research, 1−1, Higashi, Tsukuba, Ibaraki-305-8565, Japan
| | - Joan B. Seguer
- Surface Engineering Laboratory, National Institute of Materials and Chemical Research, 1−1, Higashi, Tsukuba, Ibaraki-305-8565, Japan
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45
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Murata M, Arakawa M, Yoshida T, Hato M. Binding of immunoglobulin molecules to preadsorbed protein A layers as observed by surface forces measurements. Colloids Surf B Biointerfaces 1998. [DOI: 10.1016/s0927-7765(98)00055-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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46
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Molecular dynamics simulation of water between hydrophobic surfaces. Implication for the long-range hydrophobic force. Chem Phys Lett 1998. [DOI: 10.1016/s0009-2614(98)00462-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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47
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Abstract
Molecular self association in liquids is a physical process that can dominate cohesion (interfacial tension) and miscibility. In water, self association is a powerful organizational force leading to a three-dimensional hydrogen-bonded network (water structure). Localized perturbations in the chemical potential of water as by, for example, contact with a solid surface, induces compensating changes in water structure that can be sensed tens of nanometers from the point of origin using the surface force apparatus (SFA) and ancillary techniques. These instruments reveal attractive or repulsive forces between opposing surfaces immersed in water, over and above that anticipated by continuum theory (DLVO), that are attributed to a variable density (partial molar volume) of a more-or-less ordered water structure, depending on the water wettability (surface energy) of the water-contacting surfaces. Water structure at surfaces is thus found to be a manifestation of hydrophobicity and, while mechanistic/theoretical interpretation of experimental results remain the subject of some debate in the literature, convergence of experimental observations permit, for the first time, quantitative definition of the relative terms 'hydrophobic' and 'hydrophilic'. In particular, long-range attractive forces are detected only between surfaces exhibiting a water contact angle theta > 65 degrees (herein defined as hydrophobic surfaces with pure water adhesion tension tau O = gamma O cos theta < 30 dyn/cm where gamma O is water interfacial tension = 72.8 dyn/cm). Repulsive forces are detected between surfaces exhibiting theta < 65 degrees (hydrophilic surfaces, tau O > 30 dyn/cm). These findings suggest at least two distinct kinds of water structure and reactivity: a relatively less-dense water region against hydrophobic surfaces with an open hydrogen-bonded network and a relatively more-dense water region against hydrophilic surfaces with a collapsed hydrogen-bonded network. Importantly, membrane and SFA studies reveal a discrimination between biologically-important ions that preferentially solubilizes divalent ions in more-dense water regions relative to less-dense water regions in which monovalent ions are enriched. Thus, the compelling conclusion to be drawn from the collective scientific evidence gleaned from over a century of experimental and theoretical investigation is that solvent properties of water within the interphase separating a solid surface from bulk water solution vary with contacting surface chemistry. This interphase can extend tens of nanometers from a water-contacting surface due to a propagation of differences in self association between vicinal water and bulk-phase water. Physicochemical properties of interfacial water profoundly influence the biological response to materials in a surprisingly straightforward manner when key measures of biological activity sensitive to interfacial phenomena are scaled against water adhesion tension tau O of contacting surfaces. As examples, hydrophobic surfaces (tau O < 30 dyn/cm) support adsorption of various surfactants and proteins from water because expulsion of solute from solution into the interphase between bulk solid and solution phases is energetically favorable. Adsorption to hydrophobic surfaces is driven by the reduction of interfacial energetics concomitant with replacement of water molecules at the surface by adsorbed solute (surface dehydration). Hydrophilic surfaces (tau O > 30 dyn/cm) do not support adsorption because this mechanism is energetically unfavorable. Protein-adsorbing hydrophobic surfaces are inefficient contact activators of the blood coagulation cascade whereas protein-repellent hydrophilic surfaces are efficient activators of blood coagulation. Mammalian cell attachment is a process distinct from protein adsorption that occurs efficiently to hydrophilic surfaces but inefficiently to hydrophobic surfaces. (ABSTRACT TRUNCATED)
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Affiliation(s)
- E A Vogler
- Becton Dickinson Research Center, Research Triangle Park, NC 27709-2016, USA.
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48
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Is the long-range hydrophobic attraction related to the mobility of hydrophobic surface groups? Colloids Surf A Physicochem Eng Asp 1997. [DOI: 10.1016/s0927-7757(97)00028-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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