Abstract
The interest in hollow structures with defined porosities has promoted the fabrication of colloidosomes, i.e. capsules from spherical colloids. The hierarchically organized architectures were built from microparticles or multiple layers of nanoparticles to make sure that the capsule walls were sufficiently robust. Herein, we present for the first time a strategy towards submicron-sized capsules with walls that consist of a single layer of nanoscopic inorganic constituents. Nanoparticles and oppositely charged polymer colloids were joined at the surface of evaporating emulsion droplets. The heteroaggregates exhibited well-defined core-shell morphologies, with clusters of the polymer colloids as the core and a dense monolayer of nanoparticles as the shell. Various complex yet well-defined global shapes can be obtained in respect to the number of polymer particles. Subsequent removal of the polymer core led to capsules, which exhibited regular compartmentalized shapes. A high density of nanopores was obtained on objects with dimensions of less than half a micron. Regardless of the fact that the capsules consisted of a single layer of nanoparticles with tiny contacts keeping them together, they did not collapse or break apart. Monte Carlo computer simulations demonstrated that the nanoscopic constituents can be trapped into structurally arrested states. © 2012 The Royal Society of Chemistry.