Interfacial dynamics and the static profile near a single wall in a model colloid polymer mixture

Aarts, Dirk G. A. L.; Wiel, J.H. van der; Lekkerkerker, H.N.W.

doi:10.1088/0953-8984/15/1/332

Cited by 84 publications

(138 citation statements)

References 17 publications

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“…The interfacial tensions decrease in the case of excluded volume interactions with respect to the AOV model. The comparison between our results and the experiments of Aarts et al 21 is quantitatively better than the results of the AOV model, although de Hoog and Lekkerkerker 12 show that it is difficult to obtain accurate interfacial tension measurements. In addition, we compare our results with the predictions of the extended free volume theory plus a square gradient approximation to evaluate the tension 45 and the DFT of Moncho-Jorda et al 47 The DFT uses effective one-component pair potentials between the colloids that include the excluded volume interaction according to the approach of Louis et al 46 The predictions of the two theories are very close to each other and to our simulation results.…”

Section: A Bulk Phase Behavior and Gas-liquid Interfacial Tensioncontrasting

confidence: 55%

Effect of excluded volume interactions on the interfacial properties of colloid-polymer mixtures

Fortini

Bolhuis

Dijkstra

2008

The Journal of Chemical Physics

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Effect of excluded volume interactions on the interfacial properties of colloid-polymer mixtures Fortini, A.; Bolhuis, P.G.; Dijkstra, M. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. We report a numerical study of equilibrium phase diagrams and interfacial properties of bulk and confined colloid-polymer mixtures using grand canonical Monte Carlo simulations. Colloidal particles are treated as hard spheres, while the polymer chains are described as soft repulsive spheres. The polymer-polymer, colloid-polymer, and wall-polymer interactions are described by density-dependent potentials derived by Bolhuis and Louis ͓Macromolecules 35, 1860 ͑2002͔͒. We compared our results with those of the Asakura-Oosawa-Vrij model ͓J. Chem. Phys. 22, 1255 ͑1954͒; J. Polym Sci 33, 183 ͑1958͒; Pure Appl. Chem. 48, 471 ͑1976͔͒ that treats the polymers as ideal particles. We find that the number of polymers needed to drive the demixing transition is larger for the interacting polymers, and that the gas-liquid interfacial tension is smaller. When the system is confined between two parallel hard plates, we find capillary condensation. Compared with the Asakura-Oosawa-Vrij model, we find that the excluded volume interactions between the polymers suppress the capillary condensation. In order to induce capillary condensation, smaller undersaturations and smaller plate separations are needed in comparison with ideal polymers.

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Section: A Bulk Phase Behavior and Gas-liquid Interfacial Tensioncontrasting

confidence: 55%

Effect of excluded volume interactions on the interfacial properties of colloid-polymer mixtures

Fortini

Bolhuis

Dijkstra

2008

The Journal of Chemical Physics

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“…Since the experimental parameters can be tailored to match the desired properties, such systems have become an important tool in investigating various theoretical concepts. Recent experiments on well-characterized colloid-polymer mixtures have involved studies of the wetting transition [3,4], real space observation of the thermal capillary waves [5], the fluid-fluid interfacial tension [6,7,8,9], and the interfacial width [10].…”

Section: Introductionmentioning

confidence: 99%

Demixing in athermal mixtures of colloids and excluded-volume polymers from density functional theory

Bryk

2005

The Journal of Chemical Physics

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We study the structure and interfacial properties of model athermal mixtures of colloids and excluded volume polymers. The colloid particles are modeled as hard spheres whereas the polymer coils are modeled as chains formed from tangentially bonded hard spheres. Within the framework of the nonlocal density functional theory we study the influence of the chain length on the surface tension and the interfacial width. We find that the interfacial tension of the colloid-interacting polymer mixtures increases with the chain length and is significantly smaller than that of the ideal polymers. For certain parameters we find oscillations on the colloid-rich parts of the density profiles of both colloids and polymers with the oscillation period of the order of the colloid diameter. The interfacial width is few colloid diameters wide and also increases with the chain length. We find the interfacial width for the end segments to be larger than that for the middle segments and this effect is more pronounced for longer chains.

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“…We use here two different mixtures consisting of poly(methyl methacrylate) colloids with d 142 nm mixed with polystyrene polymers in decalin (system S1) and silica colloids with d 26 nm mixed with poly(dimethylsiloxane) polymers in cyclohexane (system S2). Both systems have been extensively characterized elsewhere [15][16][17]. We measured the gas-liquid surface tension by analyzing the capillary rise against a glass wall (S1 and S2) [16,17] and the capillary wave spectrum (S1) [15,17].…”

mentioning

confidence: 99%

“…Both systems have been extensively characterized elsewhere [15][16][17]. We measured the gas-liquid surface tension by analyzing the capillary rise against a glass wall (S1 and S2) [16,17] and the capillary wave spectrum (S1) [15,17]. The measured tension is 20 (S1) and 500 nN=m (S2) for the two mixtures considered here, i.e., 5-6 orders of magnitude smaller than for water ( 0:072 N=m).…”

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Drop Formation by Thermal Fluctuations at an Ultralow Surface Tension

Hennequin¹,

Aarts

Wiel

et al. 2006

Phys. Rev. Lett.

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We present experimental evidence that drop breakup is caused by thermal noise in a system with a surface tension that is more than 10 6 times smaller than that of water. We observe that at very small scales classical hydrodynamics breaks down and the characteristic signatures of pinch-off due to thermal noise are observed. Surprisingly, the noise makes the drop size distribution more uniform, by suppressing the formation of satellite droplets of the smallest sizes. The crossover between deterministic hydrodynamic motion and stochastic thermally driven motion has repercussions for our understanding of small-scale hydrodynamics, important in many problems such as micro-or nanofluidics and interfacial singularities. DOI: 10.1103/PhysRevLett.97.244502 PACS numbers: 47.20.Dr, 47.55.df, 82.70.Dd Drop formation represents a basic phenomenon important in a wide variety of industrial and natural processes. For instance, all spraying processes, ranging from dispersing pesticides [1] to ink-jet printing, rely on controlling drop sizes for efficient application. Classically, two hydrodynamic mechanisms of drop formation are known: Surface tension always causes the breakup and is countered by either the viscosity or the inertia of the liquid [2 -6].In this Letter, we report on a different mechanism: drop formation when altered by perturbations of the interface. This leads to both qualitatively and quantitatively different behavior. It has been shown before that finite amplitude perturbations may trigger successive instabilities and qualitatively change the shape of the breakup [7,8]. In our experiments, however, the perturbations are an intrinsic property of the fluid interface: The thermal fluctuations of the interface lead to a new breakup mechanism [9,10]. Such thermal capillary waves are always present at all fluid interfaces due to the thermal energy k B T, with Boltzmann's constant k B and temperature T.To estimate at what length scales the thermal noise becomes dominant over capillary forces, a fluctuating stress S is added to the Navier-Stokes equation. Dimensional analysis gives the pressure gradient rp =L 2 , with the interfacial tension and L a characteristic length, and the gradient in the fluctuating stress tensorwhere is the viscosity, and the time t is proportional to L = . It now readily follows that at lengths L of the order of the thermal length L T k B T= p thermal noise dominates the capillary forces. This is also the typical roughness of an interface and results from the competition between surface tension that tends to keep the interface flat and thermal energy driving the fluctuations. For simple liquids, L T is typically nanometric. Consequently, the surface is flat at hydrodynamic scales, and free-surface flows such as the one occurring in droplet snapoff are very well described by the Navier-Stokes equation without fluctuations. This hydrodynamic description breaks down when the flow takes place at scales comparable to L T , which we are able to observe here by strongly decreasing the surface te...

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Interfacial dynamics and the static profile near a single wall in a model colloid polymer mixture

Cited by 84 publications

References 17 publications

Effect of excluded volume interactions on the interfacial properties of colloid-polymer mixtures

Effect of excluded volume interactions on the interfacial properties of colloid-polymer mixtures

Demixing in athermal mixtures of colloids and excluded-volume polymers from density functional theory

Drop Formation by Thermal Fluctuations at an Ultralow Surface Tension

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