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ICS-3 Group Seminar:
Coarse-Grained Modeling of Colloid-Nanoparticle Mixtures

Prof. Dr. Alan R. Denton, Department of Physics, North Dakota State University, USA

Anfang
17.07.2018 10:30 Uhr
Ende
17.07.2018 11:30 Uhr
Veranstaltungsort
Seminarraum A1-3, Building 04.6, Entrance E1

Abstract:

Interparticle interactions and bulk properties of colloidal suspensions can be substantially modified by addition of nanoparticles. Extreme asymmetries in size and charge between colloidal particles and nanoparticles present severe computational challenges to molecular modeling. I will outline a statistical mechanical theory of effective electrostatic interactions, based on a sequential coarse-graining procedure, which allows a multicomponent mixture of charged colloids, nanoparticles, and microions to be mapped first onto a binary mixture of colloids and nanoparticles [1] and then onto a one-component model of pseudo-colloids [2]. In a linear-response approximation, the one-component model is governed by a single effective pair potential and a one-body volume energy, whose parameters depend nontrivially on nanoparticle size, charge, and concentration.

To test the theory and to explore the influence of charged nanoparticles on the structure of charge-stabilized colloidal suspensions, we have performed molecular dynamics simulations. For moderate electrostatic couplings, we find that colloid-colloid radial distribution functions and static structure factors agree closely between the one- and two-component models, validating the sequential coarse-graining approach. Analysis of structural properties shows that increasing the charge and concentration of nanoparticles progressively weakens correlations between charged colloids due to enhanced screening of electrostatic interactions, promoting melting of colloidal crystals and aggregation of colloids [3]. A similar approach could be applied to explore the impact of nanoparticle dopants on suspensions of soft charged colloids, such as ionic microgels.

 

[1] Jun Kyung Chung and Alan R. Denton, "Effective electrostatic interactions in mixtures of
charged colloids," Phys. Rev. E 88, 022306 (2013).

[2] Alan R. Denton, "Effective electrostatic interactions in colloid-nanoparticle mixtures," Phys. Rev. E 96, 062610 (2017).

[3] Braden M. Weight and Alan R. Denton, "Structure and stability of charged colloid-nanoparticle mixtures," J. Chem. Phys. 148, 114904 (2018).

 

Kontakt

Prof. Dr. Gerhard Naegele
Telefon: +49 2461 61-2504
Fax: +49 2461 61-2280
E-Mail: g.naegele@fz-juelich.de

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