Nonequilibrium growth of patchy-colloid networks on substrates

Abstract

Patchy colloids with highly directional interactions are ideal building blocks to control the local arrangements resulting from their spontaneous self-organization. Here we propose their use, combined with substrates and nonequilibrium conditions, to obtain novel structures, different from those of equilibrium thermodynamic phases. Specifically, we investigate numerically the irreversible adhesion of three-patch colloids near attractive substrates, and analyze the fractal network of connected particles that is formed. The network density profile exhibits three distinct regimes, with different structural and scaling properties, which we characterize in detail. The adsorption of a mixture of three-and two-patch colloids is also considered. An optimal fraction of two-patch colloids is found where the total density of the film is maximized, in contrast to the equilibrium gel structures where a monotonic decrease of the density has been reported.

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

“…[30]. We focus on chemical or DNA mediated bonds [8,45], which are highly directional and very strong, and may be considered irreversible within the timescale of interest [46].…”

“…The quest for the feasibility of the equilibrium structures has shifted the emphasis to the kinetics [24][25][26][27] in particular to the adsorption on substrates [28][29][30][31][32]. Substrates simultaneously improve the control over assembly [33][34][35][36][37] and provide an identifiable growth direction, which helps to characterize the time evolution of growth and to develop strategies to obtain heterogeneous materials [38].…”

“…To access large-length and longtime scales, we choose not to perform detailed molecular dynamics simulations and use, instead, a stochastic model previously proposed in Ref. [30]. As schematically represented in Fig.…”

Dynamics of Patchy Particles in and out of Equilibrium

“…Equilibrium studies of patchy particle systems revealed rich phase diagrams depending on temperature and density, and in novel ways on the number and type of patches [12,18,19]. However, the potential application of these predictions may be compromised, as the feasibility of assembling the new phases is seriously hampered by the kinetic barriers that emerge from the complex particle-particle correlations [20][21][22][23][24][25][26][27][28][29][30]. Thus, understanding the dynamics towards thermodynamically stable (equilibrium) structures is vital to tackle this challenge.…”

Effect of the number of patches on the growth of networks of patchy colloids on substrates

“…Recent efforts have been focused on the nonequilibrium properties of patchy colloids, with emphasis on the structure of the adsorbed films [34][35][36] and the properties of the growing interface [37,38]. In particular, it was shown that, in the limit of irreversible adsorption, growth on substrates is sustained only for certain arrangements of the patches on the surface of the colloids, delimited by two absorbing phase transitions from thin to thick films [37].…”