  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 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.
