Microrheological consequences of attractive colloid-colloid potentials in a two-dimensional Brownian fluid

AbstractBy using microrheological methods commonly employed in videomicroscopy experiments, we study the rheology of a two-dimensional computational fluid formed by Brownian disks with the aim of exploring the influence of some effective colloid-colloid attractive interactions. The model of fluid is developed by Brownian dynamics simulations without hydrodynamical interactions, and it is characterized by calculating its equation of state from the pair distribution function. Micromechanical properties, relative and intrinsic viscosity and freezing are discussed. Then, we include attractive forces such a Asakura-Oosawa depletion force or an empiric expression proposed by Grier and Hal (GH) for an anomalous electrostatic potential observed in confined and charged colloids. By using both potentials, viscosity is clearly increased, but when the GH potential is included, viscoelastic gel state is reached for intermediate values of surface concentration. Finally, we analyse the influence of the attractive potentials in the breaking-up by thermal fluctuations of linear chains formed by 2D particles, finding that the GH potential reduces the characteristical time at which the disks can be considered as disaggregated. In this work, we employ an experimental-like methodology for the study of a Brownian hard-disk fluid, providing a very useful link with experimental procedures.

[1]  Todd M. Squires,et al.  Fluid Mechanics of Microrheology , 2010 .

[2]  J. Zasadzinski,et al.  Viscosity of two-dimensional suspensions. , 2002, Physical review letters.

[3]  D. A. Saville,et al.  Colloidal Dispersions: ACKNOWLEDGEMENTS , 1989 .

[4]  F. Ortega,et al.  Interfacial microrheology: Particle tracking and related techniques , 2010 .

[5]  A. Einstein.  Über die von der molekularkinetischen Theorie der Wärme geforderte Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen [AdP 17, 549 (1905)] , 2005, Annalen der Physik.

[6]  J. Bullard,et al.  A comparison of viscosity-concentration relationships for emulsions. , 2009, Journal of colloid and interface science.

[7]  Thomas G. Mason,et al.  Estimating the viscoelastic moduli of complex fluids using the generalized Stokes–Einstein equation , 2000 .

[8]  Sebastián Dormido,et al.  Two web-based laboratories of the FisL@bs network: Hooke's and Snell's laws , 2011 .

[9]  J. M. Pastor,et al.  Scaling in the aggregation dynamics of a magnetorheological fluid. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[10]  D. Boal,et al.  Mechanics of the cell , 2001 .

[11]  Denis Wirtz,et al.  Particle Tracking Microrheology of Complex Fluids , 1997 .

[12]  A. R. Bausch,et al.  Colloidosomes: Selectively Permeable Capsules Composed of Colloidal Particles , 2002, Science.

[13]  D. Heyes.  Shear thinning of dense suspensions modelled by Brownian dynamics , 1988 .

[14]  Anomalous interactions in confined charge-stabilized colloid , 2004, cond-mat/0404284.

[15]  A. C. Mitus,et al.  Local structure analysis of the hard-disk fluid near melting , 1997 .

[16]  N. Wagner,et al.  Colloidal Suspension Rheology: Frontmatter , 2011 .

[17]  Marcus,et al.  Self-diffusion in dilute quasi-two-dimensional hard sphere suspensions: Evanescent wave light scattering and video microscopy studies. , 1996, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics.

[18]  A. Vrij,et al.  Polymers at Interfaces and the Interactions in Colloidal Dispersions , 1976 .

[19]  D. Grier,et al.  Confinement-induced colloidal attractions in equilibrium. , 2003, Physical review letters.

[20]  Luban,et al.  Equation of state of the classical hard-disk fluid. , 1985, Physical review. A, General physics.

[21]  R. Larson.  The Structure and Rheology of Complex Fluids , 1998 .

[22]  Anthony J. C. Ladd,et al.  Hydrodynamic transport coefficients of random dispersions of hard spheres , 1990 .

[23]  Statistical and sampling issues when using multiple particle tracking. , 2007, Physical review. E, Statistical, nonlinear, and soft matter physics.

[24]  A. Ashkin,et al.  Applications of laser radiation pressure. , 1980, Science.

[25]  David M. Heyes,et al.  Brownian dynamics simulations of model hard-sphere suspensions , 1993 .

[26]  Depletion forces in nonequilibrium. , 2003, Physical review letters.

[27]  S. Eichmann,et al.  Optical microscopy measurements of kT-scale colloidal interactions , 2011 .

[28]  N. Wagner,et al.  Colloidal Suspension Rheology: Frontmatter , 2011 .

[29]  D. Heyes,et al.  The Newtonian viscosity of concentrated stabilized dispersions: Comparisons with the hard sphere fluid , 2004 .

[30]  D A Weitz,et al.  Two-point microrheology of inhomogeneous soft materials. , 2000, Physical review letters.

[31]  J. Crocker,et al.  Multiple-particle tracking and two-point microrheology in cells. , 2007, Methods in cell biology.

[32]  Georges Bossis,et al.  Field induced structure in magneto and electro-rheological fluids , 1992 .

[33]  Polymer induced depletion potentials in polymer-colloid mixtures , 2002, cond-mat/0203144.

[34]  C. Bechinger.  Colloidal suspensions in confined geometries , 2002 .

[35]  L. Forró,et al.  Resonances arising from hydrodynamic memory in Brownian motion , 2011, Nature.

[36]  F. Ree,et al.  Radial Distribution Functions and Equation of State of the Hard‐Disk Fluid , 1969 .

[37]  W. Kegel,et al.  Direct measurement of the free energy by optical microscopy. , 2006, Proceedings of the National Academy of Sciences of the United States of America.

[38]  T. Lubensky,et al.  Attractions between hard colloidal spheres in semiflexible polymer solutions , 2000 .

[39]  David G. Grier,et al.  Like-charge attractions in metastable colloidal crystallites , 1997, Nature.

[40]  C. Tsouris,et al.  Agglomeration of magnetic particles and breakup of magnetic chains in surfactant solutions , 2002 .

[41]  Sonia Melle,et al.  Morphology of anisotropic chains in a magneto-rheological fluid during aggregation and disaggregation processes. , 2009, Journal of colloid and interface science.

[42]  S. Melle,et al.  Time scaling regimes in aggregation of magnetic dipolar particles: scattering dichroism results. , 2001, Physical review letters.

[43]  C. Vega,et al.  Freezing transition and interaction potential in monolayers of microparticles at fluid interfaces. , 2011, Langmuir : the ACS journal of surfaces and colloids.

[44]  F. Cuadros,et al.  Equations of State for Hard Spheres and Hard Disks , 2008 .

[45]  J. M. Pastor,et al.  Aggregation and disaggregation dynamics of sedimented and charged superparamagnetic micro-particles in water suspension , 2011, The European physical journal. E, Soft matter.

[46]  Mason,et al.  Optical measurements of frequency-dependent linear viscoelastic moduli of complex fluids. , 1995, Physical review letters.

[47]  J. Vermant,et al.  Interfacial rheology of stable and weakly aggregated two-dimensional suspensions. , 2007, Physical chemistry chemical physics : PCCP.

[48]  D. Grier,et al.  Pair interaction of charged colloidal spheres near a charged wall. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[49]  J. Brady,et al.  Microrheology of colloidal dispersions by Brownian dynamics simulations , 2005 .

[50]  D. Grier,et al.  Methods of Digital Video Microscopy for Colloidal Studies , 1996 .

[51]  Francisco Esquembre,et al.  Easy Java Simulations: a software tool to create scientific simulations in Java , 2004 .

[52]  Fumio Oosawa,et al.  Interaction between particles suspended in solutions of macromolecules , 1958 .

[53]  Daniel J. Klingenberg,et al.  Electrorheology : mechanisms and models , 1996 .