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DY: Fachverband Dynamik und Statistische Physik
DY 35: Reaction-Diffusion Systems
DY 35.7: Vortrag
Donnerstag, 3. April 2014, 16:45–17:00, HÜL 186
Formation of patchy particles by diffusion limited growth — •Timo Bihr1,2, Huixin Bao3, Robin Klupp Taylor3, Udo Seifert2, and Ana-Sunčana Smith1 — 1Institut für Theoretische Physik and Excellence Cluster: Engineering of Advanced Materials, Universität Erlangen-Nürnberg — 2II. Institut für Theoretische Physik, Universität Stuttgart — 3Institute of Particle Technology, Universität Erlangen-Nürnberg
Patchy particles can be formed by coating polystyrene particles with ascorbic acid as a precursor for gold. The latter precipitates from the solution onto the particle, diffuses on its surface and attaches to a growing gold patch. We investigate the formation of the patch by Monte Carlo simulations and study the effects of gold concentration, binding and unbinding rates, and the diffusion constant. We obtain a variety of dendrite structures which we characterize by their fractal dimension and the power-law characterizing the growth process. The exponents typical for the diffusion limited aggregation are recovered only in the limit of infinite dilution, whereas reaction limited dynamics is obtained at larger densities, depending on the binding affinity. Comparison of modeling with experiments shows that decreasing the concentration of the ascorbic acid results in the decrease of binding affinity, whereas increasing the temperature increases the diffusivity. Consequently in both cases, roughening of the dendrite structure of the patches takes place. The understanding of this process allows us to tune the morphology of the patch on the particle from dense cup-like structures to pure dendrites (H. Bao et al. Nanoscale, 2014, DOI: 10.1039/C3NR04016J).