Title: Building, modeling, and predicting colloidal patchy particle architectures

Speaker: Hannah Jonas (UvA)

Abstract:

Colloidal patchy particles are micron-sized particles dressed with hydrophobic patches that can form directed bonds via critical Casimir interactions controlled by temperature when suspended in a critical binary solvent. Patchy particles are suited as a model system to explore complex structures analogous to molecular architectures, exhibiting similar statistical behavior as atoms and molecules but with the great advantage of being directly observable with e.g. confocal microscopy [1].

Here we build a computational model for patchy particles based on theoretical critical Casimir potentials benchmarked onto experimental measurements of the particles’ collective behavior. The model mimics flexibility and structural distributions of dipatch particle colloidal chains at various densities and tetrapatch particle colloidal cyclopentane as function of critical Casimir interaction strength [1-3]. Using our accurate model we are now able to perform large scale simulations of the colloidal architectures formed in mixtures of di- and tetrapatch particles.

In 2D and 3D systems, the thermodynamic properties of patchy particles can be predicted based on their potential with Werheim and Flory-Stockmayer theory [4,5]. However, the patchy particles at interest live in a quasi-2D plane due to gravity pulling them down. We have extended the Wertheim theory to quasi-2D and are now able to predict the equilibrium distributions of colloidal architectures.

[1] P. Swinkels et al., Nat. Comm. 2021, 12, 2810

[2] S. Stuij et al., Soft Matter 2017,13,5233

[3] H. Jonas et al., under review

[4] F. Sciortino et al., J. Chem. Phys. 2007, 126, 194903

[5] F. Sciortino, E. Zaccarelli, Curr Opin Solid State Mater Sci 2011, 15, 246

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