Aggregation kinetics of paramagnetic colloidal particles

Autor:	Marc Fermigier, Joanne H. E. Promislow, Alice P. Gast
Rok vydání:	1995
Předmět:	Physics Condensed matter physics Smoluchowski coagulation equation Critical phenomena General Physics and Astronomy Dipole symbols.namesake Volume fraction symbols Particle Physical and Theoretical Chemistry Diffusion (business) Scaling Dimensionless quantity
Zdroj:	The Journal of Chemical Physics. 102:5492-5498
ISSN:	1089-7690 0021-9606
DOI:	10.1063/1.469278
Popis:	Magnetic‐field‐induced chain formation of superparamagnetic latex particles is investigated via optical microscopy and digital image analysis. Our experiment is unique in that the aggregation process takes place in the bulk, where particles are free to diffuse in three dimensions, rather than on a surface. We find that the mean chain size 〈s(t)〉 has a power‐law dependence on time, 〈s(t)〉∼tz, as predicted by the Smoluchowski equation and three‐dimensional simulations of diffusion‐limited aggregation of oriented particles. The value of the exponent z is found to have a weak inverse dependence on particle volume fraction φ and dimensionless dipole strength λ. We propose a new model for a characteristic time scale proportional to 1/λ and 1/φ. Comparison with experimental observations shows this scaling to be very effective but to break down suddenly above a critical volume fraction.
Databáze:	OpenAIRE
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