[Zurück]

E. Bianchi, S. Ferrari, E. G. Noya, G. Kahl:
"On the propensity of inverse patchy colloids to self-organize in stable, lamellar structures";
Poster: 10th Liquid Matter Conference (2017), Ljubljana; 17.07.2017 - 21.07.2017; in: "Liquids 2017 10TH LIQUID MATTER CONFERENCE", (2017), S. 5.021.

Inverse patchy colloids (IPCs) are mesoscopic particles that are characterized by a heterogeneously charged surface [1]: the charged colloid is decorated by regions of opposite charge (so-called patches). As a consequence of the attraction and the repulsion of the regions of unlike and like charges IPCs are able to form selective and
strongly oriented bonds with other particles. As an additional feature, the differently charged regions of IPCs can be addressed by external stimuli, such as electric fields.
We consider in our simulation-based investigations a two-patch model of an IPC: here the patches are located on the poles, leaving the oppositely charged equatorial region uncovered. Via direct pole-equator contacts, interacting IPCs are able to form very strong bonds. This bonding pattern is the basis of the propensity of IPCs to form planar aggregates. The lamellae occur, for instance, as monolayers close to charged substrates [1, 2] or as stacked, parallel layers in bulk equilibrium phases [3], where their range of stability covers a large portion of the parameter space. Recently a novel layered structure has been identified for a particular class of IPCs [4]: it occurs at low temperatures as a stack of parallel layers (each of them characterized by a strong internal bonding pattern), which are stabilized by inter-layer particles that are oriented perpendicularly to the lamellae. As the temperature is increased the system forms an
unconventional hybrid crystal-liquid structure: the inter-layer particles have now sufficient energy to become mobile and start to diffuse (as quantified via different dynamic correlation functions) between the layers which still maintain their stable and rigid internal structure. As the temperature is further increased, also the strong intralayer bonds start to break up and the system eventually melts, realizing thus the second steps in this remarkable two-stage melting process. This (semi-)ordered structure is able to quickly and spontaneously self-organize in simulations (even when starting from a completely random initial configuration) and shows very pronounced
self-healing capacities.

[1] E. Bianchi, C.N. Likos, and G. Kahl, ACS Nano 7, 4657 (2013).
[2] E. Bianchi, C.N. LIkos, and G. Kahl, Nano Letters 14, 3412 (2014).
[3] E.G. Noya and E. Bianchi, J. Phys. Condens. Matter 27, 234103 (2015).
[4] S. Ferrari, E. Bianchi, and G. Kahl, Nanoscale (DOI 10.1039/C6NR07987C)

Inverse patchy colloids self-organization self-assembly

http://publik.tuwien.ac.at/files/publik_266976.pdf

Projektleitung Gerhard Kahl:
DFS