Nucleation-enhanced condensation and fast shedding on self-lubricated silicone organogels

A cross-linked silicone elastomer swollen in silicone oil releases at its surface a thin oil layer, whose thickness slowly increases with time as a consequence of surface energy minimization and residual crosslinking reactions within the polymer matrix. Here, we tune and characterize this oil layer thickness (between 0 and 5 μm) in order to show its quantitative influence on the physical mechanisms at play during water condensation: droplet nucleation and growth, coarsening by menisci-mediated coalescences, and droplet shedding by gravity. We show that continuous nucleation is at the origin of enhanced condensation. Spontaneous replenishment of the oil layer occurs thanks to the storage of oil in the bulk of the swollen elastomer, allowing the same sample to be used for repeated long-lasting condensation experiments. The oil layer released at the surface of an organogel is shown to promote continuous droplet nucleation and menisci-mediated coalescences during water condensation, and to sustainably ensure gravity-induced drainage of droplets.