Spraying makes it smoother: Commercial reverse osmosis processes for water desalination use membranes made by the polymerization of polyamide at the oil/water interface. Chowdhury et al. show that thinner, smoother membranes can be made with an electrospray technique. Using high voltage, the two precursors are finely sprayed onto a substrate and polymerize on contact. The composition of the resulting membrane can be tuned on the basis of the proportion of the two components. At optimum conditions, the membranes appear to be better at desalination than current commercial reverse osmosis membranes. Science , this issue p. 682

Polymer membranes perform innumerable separations with far-reaching environmental implications. Despite decades of research, design of new membrane materials remains a largely Edisonian process. To address this shortcoming, we demonstrate a generalizable, accurate machine learning (ML) implementation for the discovery of innovative polymers with ideal performance. Specifically, multitask ML models are trained on experimental data to link polymer chemistry to gas permeabilities of He, H ₂ , O ₂ , N ₂ , CO ₂ , and CH ₄ . We interpret the ML models and extract valuable insights into the contributions of different chemical moieties to permeability and selectivity. We then screen over 9 million hypothetical polymers and identify thousands that lie well above current performance upper bounds, including hundreds of never-before-seen ultrapermeable polymer membranes with O ₂ and CO ₂ permeability greater than 10 ⁴ and 10 ⁵ Barrers, respectively. High-fidelity molecular dynamics simulations confirm the ML-predicted gas permeabilities of the promising candidates, which suggests that many can be translated to reality.