Chromatic patchy particles: effects of specific interactions on liquid structure

TL;DR

This study investigates how specific 'chromatic' interactions, modeled as DNA-linked patches, influence the structure and stability of patchy particle liquids, revealing that colorless systems are denser and more stable than chromatic ones.

Contribution

It introduces the concept of chromatic interactions in patchy particles and compares their structural and thermodynamic effects to colorless systems using MD simulations.

Findings

Colorless patchy particles form better connected, denser aggregates.

Chromatic interactions reduce liquid stability and favor crystalline phases.

Chromatic interactions expand the crystalline phase region in the phase diagram.

Abstract

We study the structural and thermodynamic properties of patchy particle liquids, with a special focus on the role of "color", i.e. specific interactions between individual patches. A possible experimental realization of such "chromatic" interactions is by decorating the particle patches with single-stranded DNA linkers. The complementarity of the linkers can promote selective bond formation between predetermined pairs of patches. By using MD simulations, we compare the local connectivity, the bond orientation order, and other structural properties of the aggregates formed by the "colored" and "colorless" systems. The analysis is done for spherical particles with two different patch arrangements (tetrahedral and cubic). It is found that the aggregated (liquid) phase of the "colorless" patchy particles is better connected, denser and typically has stronger local order than the corresponding "colored" one. This, in turn, makes the colored liquid less stable thermodynamically. Specifically, we predict that in a typical case the chromatic interactions should increase the relative stability of the crystalline phase with respect to the disordered liquid, thus expanding its region in the phase diagram.