Effective interaction between hard sphere colloidal particles in a polymerizing Yukawa solvent

1999 ◽  
Vol 110 (16) ◽  
pp. 8189-8196 ◽  
Author(s):  
R. H. Gee ◽  
D. Henderson ◽  
A. Kovalenko
Keyword(s):  
Hard Sphere ◽  
Colloidal Particles ◽  
Effective Interaction

Theory and calculation of colloidal depletion interaction

2018 ◽  
Vol 32 (18) ◽  
pp. 1840005 ◽  
Author(s):  
Hongru Ma
Keyword(s):  
Hard Sphere ◽  
Density Functional ◽  
Colloidal Particles ◽  
Hard Spheres ◽  
Effective Interaction ◽  
Density Functional Theory Method ◽  
Ratio Method ◽  
Colloidal System ◽  
Colloidal Systems ◽  
Depletion Interaction

Colloidal dispersion is composed of particles with size ranging from 1 nm to [Formula: see text]m dispersed in solvents. There are the volume exclusion interaction and other interactions between colloidal particles, of which the former interaction causes the depletion effect. When a big sphere is immersed in the colloidal system of small spheres, there is a depletion layer around the big sphere where the center of small sphere cannot enter. The depletion layers of two big spheres overlap if they are close to each other, increasing the free volume accessed by small spheres and thereby enlarging the entropy of the system. As a result, an effective interaction between the two big spheres is resulted from the change of entropy as a function of their distance, which is referred to as the depletion interaction. This paper first introduces the concept and scenario of the depletion interaction in colloidal systems. Then we briefly introduce various numerical or simulations methods of the depletion interaction of hard sphere systems, such as the acceptance ratio method, Wang–Landau method, and the density functional theory method. Taking the Asakura–Oosawa model as an example, we introduce a useful approximation method, Derjaguin approximation as well as the derivation of some approximate formula for the depletion interaction of different hardcore colloidal systems, such as between a pair of spheres in mono-disperse small spheres, between a hard sphere and a hard wall in a liquid of small spheres, and between a pair of hard spheres in a liquid of thin rods and thin disks.

Stability of a Binary Colloidal Suspension and its effect on Colloidal Processing

1989 ◽  
Vol 155 ◽  
Author(s):  
Wan V. Shih ◽  
Wei-Heng Shih ◽  
Jun Liu ◽  
Ilhan A. Aksay
Keyword(s):  
Particle Size ◽  
Hard Sphere ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Fluid Phase ◽  
Ceramic Processing ◽  
Colloidal Processing ◽  
Interparticle Interactions ◽  
The Stability ◽  
Binary Suspension

The stability of a colloidal suspension plays an important role in colloidal processing of materials. The stability of the colloidal fluid phase is especially vital in achieving high green densities. By colloidal fluid phase, we refer to a phase in which colloidal particles are well separated and free to move about by Brownian motion, By controlling parameters such as pH, salt concentration, and surfactants, one can achieve high packing (green) densities in the repulsive regime where the suspension is well dispersed as a colloidal fluid, and low green densities in the attractive regime where the suspensions are flocculated [1,2]. While there is increasing interest in using bimodal suspensions to improve green densities, neither the stability of a binary suspension as a colloidal fluid nor the stability effects on the green densities have been studied in depth as yet. Traditionally, the effect of using bimodal-particle-size distribution has only been considered in terms of geometrical packing developed by Furnas and others [3,4]. This model is a simple packing concept and is used and useful for hard sphere-like repulsive interparticle interactions. With the advances in powder technology, smaller and smaller particles are available for ceramic processing. Thus, the traditional consideration of geometrial packing for the green densities of bimodal suspensions may not be enough. The interaction between particles must be taken into account.

scholarly journals Ion-specific thermodynamical properties of aqueous proteins

2010 ◽  
Vol 82 (1) ◽  
pp. 109-126 ◽  
Author(s):  
Eduardo R.A. Lima ◽  
Evaristo C. Biscaia Jr. ◽  
Mathias Boström ◽  
Frederico W. Tavares
Keyword(s):  
Electrostatic Interactions ◽  
Colloidal Particles ◽  
Effective Interaction ◽  
Virial Coefficients ◽  
Water Structure ◽  
Hydrophobic Surface ◽  
Colloidal Systems ◽  
Salt Solutions ◽  
Monovalent Ions ◽  
Pharmaceutical Industries

Ion-specific interactions between two colloidal particles are calculated using a modified Poisson-Boltzmann (PB)equationandMonteCarlo(MC)simulations. PBequationspresentgoodresultsofionicconcentration profiles around a macroion, especially for salt solutions containing monovalent ions. These equations include not only electrostatic interactions, but also dispersion potentials originated from polarizabilities of ions and proteins. This enables us to predict ion-specific properties of colloidal systems. We compared results obtained from the modified PB equation with those from MC simulations and integral equations. Phase diagrams and osmotic second virial coefficients are also presented for different salt solutions at different pH and ionic strengths, in agreement with the experimental results observed Hofmeister effects. In order to include the water structure and hydration effect, we have used an effective interaction obtained from molecular dynamics of each ion and a hydrophobic surface combined with PB equation. The method has been proved to be efficient and suitable for describing phenomena where the water structure close to the interface plays an essential role. Important thermodynamic properties related to protein aggregation, essential in biotechnology and pharmaceutical industries, can be obtained from the method shown here.

scholarly journals Self-assembly mechanism in colloids: perspectives from statistical physics

Open Physics ◽  
2012 ◽  
Vol 10 (3) ◽  
Author(s):  
Achille Giacometti
Keyword(s):  
Integral Equation ◽  
Self Assembly ◽  
Hard Sphere ◽  
Statistical Physics ◽  
Colloidal Particles ◽  
Building Blocks ◽  
Computational Effort ◽  
Spherical Particles ◽  
Square Well ◽  
Patchy Colloids

AbstractMotivated by recent experimental findings in chemical synthesis of colloidal particles, we draw an analogy between self-assembly processes occurring in biological systems (e.g. protein folding) and a new exciting possibility in the field of material science. We consider a self-assembly process whose elementary building blocks are decorated patchy colloids of various types, that spontaneously drive the system toward a unique and predetermined targeted macroscopic structure. To this aim, we discuss a simple theoretical model — the Kern-Frenkel model — describing a fluid of colloidal spherical particles with a pre-defined number and distribution of solvophobic and solvophilic regions on their surface. The solvophobic and solvophilic regions are described via a short-range square-well and a hard-sphere potentials, respectively. Integral equation and perturbation theories are presented to discuss structural and thermodynamical properties, with particular emphasis on the computation of the fluid-fluid (or gas-liquid) transition in the temperaturedensity plane. The model allows the description of both one and two attractive caps, as a function of the fraction of covered attractive surface, thus interpolating between a square-well and a hard-sphere fluid, upon changing the coverage. By comparison with Monte Carlo simulations, we assess the pros and the cons of both integral equation and perturbation theories in the present context of patchy colloids, where the computational effort for numerical simulations is rather demanding.

Effective interaction between charged colloidal particles near a surface

1998 ◽  
Vol 95 (3) ◽  
pp. 649-655 ◽  
Author(s):  
DAVID GOULDING ◽  
JEAN-PIERRE HANSEN
Keyword(s):  
Colloidal Particles ◽  
Effective Interaction

scholarly journals Effective-interaction approach to the Fermi hard-sphere system

2015 ◽  
Vol 91 (3) ◽  
Author(s):  
Angela Mecca ◽  
Alessandro Lovato ◽  
Omar Benhar ◽  
Artur Polls
Keyword(s):  
Hard Sphere ◽  
Effective Interaction ◽  
Interaction Approach

From near hard spheres to colloidal surfboards

2016 ◽  
Vol 191 ◽  
pp. 325-349 ◽  
Author(s):  
Ljiljana Palangetic ◽  
Kirill Feldman ◽  
Raphael Schaller ◽  
Romana Kalt ◽  
Walter R. Caseri ◽  
...  
Keyword(s):  
Hard Sphere ◽  
Colloidal Particles ◽  
Hard Spheres ◽  
Building Blocks ◽  
Mechanical Deformation ◽  
Polystyrene Latex ◽  
Colloidal Gels ◽  
Core Size ◽  
H Nmr ◽  
Pmma Particles

This work revisits the synthesis of the colloidal particles most commonly used for making model near hard suspensions or as building blocks of model colloidal gels, i.e. sterically stabilised poly(methyl methacrylate) (PMMA) particles. The synthesis of these particles is notoriously hard to control and generally the problems are ascribed to the difficulty in synthesising the graft stabiliser (PMMA-g-PHSA). In the present work, it is shown that for improving the reliability of the synthesis as a whole, control over the polycondensation of the 12-polyhydroxystearic acid is the key. By changing the catalyst and performing the polycondensation in the melt, the chain length of the 12-polyhydroxystearic acid is better controlled, as confirmed by 1H-NMR spectroscopy. Control over the graft copolymer now enables us to make small variations of near hard sphere colloids, for example spherical PMMA particles with essentially the same core size and different stabilising layer thicknesses can now be readily produced, imparting controlled particle softness. The PMMA spheres can be further employed to create, in gram scale quantities, colloidal building blocks having geometrical and/or chemical anisotropy by using a range of mechanical deformation methods. The versatility of the latter methods is demonstrated for polystyrene latex particles as well.

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