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Colloids are particles that have a diameter of between approximately 1 and 1,000 nanometres and that are evenly dispersed in fluids. Colloids are also known as colloidal dispersions because the particles remain dispersed and don't settle to the bottom.
Biological systems vital functions are based on non-equilibrium states driven by consumption of chemical fuels. Here the authors show a spatiotemporal control over the formation of hydrophobic colloids, hydrogels or inks through a chemical reaction network of dicarboxylate compounds fuelled by carbodiimide.
Self-driven particles can drive the system out of equilibrium without the help of external forces. Here Bain et al. develop a model for two groups of motile bodies targeting opposite directions and show that the system exhibits critical behaviour as a function of particle density.
Ensembles of magnetic colloids can undergo an instability triggering the formation of clusters that move faster than the particles themselves. The many-body process relies on hydrodynamics alone and may prove useful for load delivery in fluidics.