Adsorbed films of three-patch colloids: Continuous and discontinuous transitions between thick and thin films

TL;DR

This study numerically explores how the spatial arrangement of patches on three-patch colloids influences their irreversible adsorption on a substrate, revealing continuous and discontinuous phase transitions between thick and thin films.

Contribution

It demonstrates the dependence of adsorption kinetics on patch angles and flexibility, identifying phase transition types and their relation to universality classes.

Findings

Growth is suppressed outside certain angle ranges.

Two phase transitions are identified: continuous at minimum angle, discontinuous at maximum angle.

Flexibility affects the range of angles supporting growth and the nature of the transitions.

Abstract

We investigate numerically the role of spatial arrangement of the patches on the irreversible adsorption of patchy colloids on a substrate. We consider spherical three-patch colloids and study the dependence of the kinetics on the opening angle between patches. We show that growth is suppressed below and above minimum and maximum opening angles, revealing two absorbing phase transitions between thick and thin film regimes. While the transition at the minimum angle is continuous, in the Directed Percolation class, that at the maximum angle is clearly discontinuous. For intermediate values of the opening angle, a rough colloidal network in the Kardar-Parisi-Zhang universality class grows indefinitely. The nature of the transitions was analyzed in detail by considering bond flexibility, defined as the dispersion of the angle between the bond and the center of the patch. For the range of flexibilities considered we always observe two phase transitions. However, the range of opening angles where growth is sustained increases with flexibility. At a tricritical flexibility, the discontinuous transition becomes continuous. The practical implications of our findings and the relation to other nonequilibrium transitions are discussed.