8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Thu 811:10-14:00P8.55Aggregation kinetics of short-range attractive particles:Brownian dynamics simulations vs. SmoluchowskiequationIgor Stankovic, 1 Aleksandar Belic, 1 and Milan Zezelj 11 Scientific Computing Laboratory, Institute of Physics Belgrade, University of Belgrade,Pregrevica 118, 11080, Belgrade-Zemun, SerbiaWe revisit the aggregation dynamics of particles interacting with short-range attractive interaction.Agglomeration of particles in suspensions is common in many technological and biologicalprocesses. Sol-gel synthesis of nanoporous structures is a prominent example [1]. However, thephysical mechanism of process parameter influence on synthesis process is still unclear. UsingBrownian Dynamics simulations we follow the relaxation of a homogeneous, thermodynamicallyunstable system towards equilibrium gel phase by agglomeration. Both structural and rheologicalproperties of gel and are followed and compared with the experimental data [1, 2]. The dynamicsof the transition is characterized by the creation and growth of clusters with fractal dimensionwhich exhibit an exponential size distribution. A phenomenological time scaling law is introducedin order to collapse time evolution of the number of clusters onto a single universal curve for arange of diffusion rates and densities. We find that if particle density is sufficiently high, formedclusters agglomerate into a single cluster spanning the system, and explain by excluded volumegrowth. Furthermore, we model these systems by a Smoluchowski coagulation equation. Fromsimulations, we calculate rate coefficients of coagulation equation and find that hat they exhibit asimple exponential dependency on cluster size.[1] A. Golubovic, M. Scepanovic, A. Kremenovic, S. Askrabic, V. Berec, Z. Dohcevic-Mitrovic, Z. V. Popovic, J. Sol-Gel Sci. Technol. 49, 311 (2009).[2] A. Ponton, S. Barboux-Doeuff and C. Sanchez, Colloids Surf. A: Physicochem. Eng. Asp.162, 177 (1999).55