Dynamics of a network fluid within the liquid-gas coexistence region

TL;DR

This study investigates the unique relaxation dynamics of low-density, valence-limited molecular networks within the liquid-gas coexistence region, revealing a scale-free relaxation process driven by percolation rather than surface tension.

Contribution

It combines Langevin simulations and Wertheim's theory to uncover a scale-free relaxation mechanism and gel formation in valence-limited networks, contrasting with isotropic particle behavior.

Findings

Scale-free relaxation dynamics observed in valence-limited networks

Gel formation occurs via a percolation transition in the Random Percolation class

Different relaxation mechanisms compared to isotropic particles

Abstract

Low-density networks of molecules or colloids are formed at low temperatures when the interparticle interactions are valence limited. Prototypical examples are networks of patchy particles, where the limited valence results from highly directional pairwise interactions. We combine extensive Langevin simulations and Wertheim's theory of association to study these networks. We find a scale-free (relaxation) dynamics within the liquid-gas coexistence region, which differs from that usually observed for isotropic particles. While for isotropic particles the relaxation dynamics is driven by surface tension (coarsening), when the valence is limited, the slow relaxation proceeds through the formation of an intermediate non-equilibrium gel via a geometrical percolation transition in the Random Percolation universality class.