Self-lubricated silicones for enhanced atmospheric water vapour collection

Access to fresh water is of significant importance in the context of global warming. Polydimethylsiloxane (PDMS) has a high emissivity in the atmospheric window between 8 and 13 µm, which ensures efficient radiative sky cooling to possibly induce water condensation¹. Self-lubricated polydimethylsiloxane (iPDMS), crosslinked PDMS swollen in silicone oil, displays a self-healing oil layer with increasing thickness (in the µm range) due to surface energy minimization and residual elastomer crosslinking². During water vapour condensation on iPDMS, the interplay between water droplets and the lubricating and droplet-cloaking oil layer insures a rapid growth of the droplets via the synergetic effects of droplet mobility, oil-menisci mediated capillary attraction, and re-nucleation in cleared regions. With an increase of the oil layer thickness, up to an order of magnitude increase of the condensation rate is found in the early stage of condensation due to the continuous nucleation within the cloaking oil and in the cleared regions left by the long-range coalescence events. During gravity-assisted water vapour collection, an increase of the oil thickness is shown to decrease the latency time for shedding (from 1h to 5min) and to increase the collected water volumes (+50%, after 4h).

1. E. Lee and T.Luo, Solar Energy Materials and Solar Cells, 2019, 194, 222-228.

2. N. Lavielle, D. Asker, B. D. Hatton, Soft Matter, 2021, 17, 936-946.