Supporting data for "Nanoscale control of internal inhomogeneity enhances water transport in desalination membranes"

Biological membranes can achieve remarkably high permeabilities while maintaining ideal selectivities by relying on homogeneous internal nanoscale structures in the form of membrane proteins. We apply such design strategies to desalination membranes. A series of polyamide desalination membranes, synthesized in an industrial-scale manufacturing line that vary in processing conditions but retain similar chemical compositions, show increasing water permeability and active layer thickness with constant NaCl selectivity. Transmission electron microscopy measurements enable determination of nanoscale three-dimensional polyamide density maps and predictions of water permeability with zero adjustable parameters. Density fluctuations are detrimental to water transport, making systematic control over nanoscale polyamide inhomogeneity a key route to maximizing water permeability without sacrificing salt selectivity in desalination membranes.