Controlling Colloidal Morphologies by Critical Casimir Forces

Shelke, Pradip B.; Nguyen, Van Duc; Limaye, A. V.; Schall, Peter

doi:10.1002/adma.201204458

Cited by 33 publications

(43 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Aggregation of colloids in a near-critical binary solvent has been studied experimentally on the ground and under microgravity conditions [68,85,194,195]. intensity I(q, t) revealed that I(q, t) exhibits a maximum at q = q * (t), which corresponds to the inverse of the mean cluster size.…”

Section: F Aggregation Kinetics and Structures Of Aggregatesmentioning

confidence: 99%

Collective behavior of colloids due to critical Casimir interactions

Maciołek

Dietrich

2018

Rev. Mod. Phys.

View full text Add to dashboard Cite

If colloidal solute particles are suspended in a solvent close to its critical point, they act as cavities in a fluctuating medium and thereby restrict and modify the fluctuation spectrum in a way which depends on their relative configuration. As a result effective, so-called critical Casimir forces (CCFs) emerge between the colloids. The range and the amplitude of CCFs depend sensitively on the temperature and the composition of the solvent as well as on the boundary conditions of the order parameter of the solvent at the particle surfaces. These remarkable, moreover universal features of the CCFs provide the possibility for an active control over the assembly of colloids.This has triggered a recent surge of experimental and theoretical interest in these phenomena. We present an overview of current research activities in this area. Various experiments demonstrate the occurrence of thermally reversible self-assembly or aggregation or even equilibrium phase transitions of colloids in the mixed phase below the lower consolute points of binary solvents. We discuss the status of the theoretical description of these phenomena, in particular the validity of a description in terms of effective, one-component colloidal systems and the necessity of a full treatment of a ternary solvent-colloid mixture. We suggest perspectives on the directions towards which future research in this field might develop.

show abstract

Section: F Aggregation Kinetics and Structures Of Aggregatesmentioning

confidence: 99%

Collective behavior of colloids due to critical Casimir interactions

Maciołek

Dietrich

2018

Rev. Mod. Phys.

View full text Add to dashboard Cite

show abstract

“…The composition of solvent 2 is still sufficiently close to the critical one that critical density fluctuations occur. 6,10,18 The chosen experimental systems have the advantage that the particle refractive index matches that of the solvent, allowing direct imaging of particles and determination of g(r) deep in the bulk of the suspension. The particles are dyed, allowing us to image them under fluorescent illumination.…”

Section: A Colloidal System and Potential Measurementmentioning

confidence: 99%

“…We investigate two well-characterized systems 10,18 of poly-n-isopropyl acrylamide (PNIPAM) particles with a diameter of σ = 500 nm suspended in a near-critical quasi binary solvent composed of 3-methyl pyridine (3MP), water, and heavy water. 19,20 The two systems differ only in the relative mass fractions w x of the solvent components x (x = 3MP, H 2 O, D 2 O), as shown in Table I.…”

Section: A Colloidal System and Potential Measurementmentioning

confidence: 99%

“…c) Electronic mail: ducnguyen@uva.nl d) Electronic mail: p.g.bolhuis@uva.nl e) Electronic mail: ps@peterschall.de ilar temperature control of phase behavior for many different colloids. 10 The question is then how to predict the phase behavior: because of the complexity of the critical Casimir interactions, the possible importance of many-body effects and the potential coupling between ions and solvent concentration fluctuations, 11,12 there has been much discussion recently about the nature of the interactions and the relevant terms to be included. [13][14][15][16] Effective pair interactions have been discussed to provide a good description of colloidal phase behavior in reasonably dilute suspensions, 13 and such effective interactions have been computed recently based on scaling functions calculated using the Ising model and combined with the Derjaguin approximation, 13 and using simple solvent models with short-range interactions.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Temperature-sensitive colloidal phase behavior induced by critical Casimir forces

Dang

Verde

Nguyen

et al. 2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

We report Monte Carlo simulations of phase behavior of colloidal suspensions with near-critical binary solvents using effective pair potentials from experiments. At off-critical solvent composition, the calculated phase diagram agrees well with measurements of the experimental system, indicating that many-body effects are limited. Close to the critical composition, however, agreement between experiment and simulation becomes poorer, signaling the increased importance of many-body effects. Both at and off the critical solvent concentration, the colloidal phase diagram is qualitatively similar to those of molecular systems and obeys the principle of corresponding states with one striking difference: it occurs in a narrow temperature interval of <1 • C below the solvent phase separation temperature.

show abstract

“…As far as the theoretical side is concerned, it was de Gennes who first obtained the CCF between spherical particles [53] considering a local freeenergy functional. Among the other techniques used to study the CCF in sphere-plate and sphere-sphere geometries are the Ornstein-Zernike theory [54], conformal invariance methods [55][56][57], Monte Carlo calculations [58][59][60][61][62][63][64][65][66][67], fluid-particle dynamics simulations [68,69], mean-field type [70][71][72][73][74] and density-functional [75] theory calculations combined with the Derjaguin approximation [44,[76][77][78]. Several review articles and works [8,[79][80][81][82] summarize both the experimental and theoretical results presented there.…”

Section: Introductionmentioning

confidence: 99%

Sign change in the net force in sphere-plate and sphere-sphere systems immersed in nonpolar critical fluid due to the interplay between the critical Casimir and dispersion van der Waals forces

Valchev

Dantchev

2017

Phys. Rev. E

View full text Add to dashboard Cite

We study systems in which both long-ranged van der Waals and critical Casimir interactions are present. The last arise as an effective force between bodies when immersed in a near-critical medium, say a nonpolar onecomponent fluid or a binary liquid mixture. They are due to the fact that the presence of the bodies modifies the order parameter profile of the medium between them as well as the spectrum of its allowed fluctuations. We study the interplay between these forces, as well as the total force (TF) between a spherical colloid particle and a thick planar slab, and between two spherical colloid particles. We do that using general scaling arguments and mean-field type calculations utilizing the Derjaguin and the surface integration approaches. They both are based on data of the forces between two parallel slabs separated at a distance L from each other, confining the fluctuating fluid medium characterized by its temperature T and chemical potential µ. The surfaces of the colloid particles and the slab are coated by thin layers exerting strong preference to the liquid phase of the fluid, or one of the components of the mixture, modeled by strong adsorbing local surface potentials, ensuring the socalled (+, +) boundary conditions. On the other hand, the core region of the slab and the particles, influence the fluid by long-ranged competing dispersion potentials. We demonstrate that for a suitable set of colloids-fluid, slab-fluid, and fluid-fluid coupling parameters the competition between the effects due to the coatings and the core regions of the objects involved result, when one changes T , µ or L, in sign change of the Casimir force (CF) and the TF acting between the colloid and the slab, as well as between the colloids. This can be used for governing the behavior of objects, say colloidal particles, at small distances, say in colloid suspensions for preventing flocculation. It can also provide a strategy for solving problems with handling, feeding, trapping and fixing of microparts in nanotechnology. Data for specific substances in support of the experimental feasibility of the theoretically predicted behavior of the CF and TF have been also presented.

show abstract

Controlling Colloidal Morphologies by Critical Casimir Forces

Cited by 33 publications

References 19 publications

Collective behavior of colloids due to critical Casimir interactions

Collective behavior of colloids due to critical Casimir interactions

Temperature-sensitive colloidal phase behavior induced by critical Casimir forces

Sign change in the net force in sphere-plate and sphere-sphere systems immersed in nonpolar critical fluid due to the interplay between the critical Casimir and dispersion van der Waals forces

Contact Info

Product

Resources

About