The successful implementation of thin-film composite membranes (TFCM) for challenging solute-solute separations in the pharmaceutical industry requires a fine control over the microstructure (size, distribution, and connectivity of the free-volume elements) and thickness of the selective layer. For example, desalinating antibiotic streams requires highly interconnected free-volume elements of the right size to block antibiotics but allow the passage of salt ions and water. Here, we introduce stevioside, a plant-derived contorted glycoside, as a promising aqueous phase monomer for optimizing the microstructure of TFCM made via interfacial polymerization. The low diffusion rate and moderate reactivity of stevioside, together with its nonplanar and distorted conformation, produced thin selective layers with an ideal microporosity for antibiotic desalination. For example, an optimized 18-nm membrane exhibited an unprecedented combination of high water permeance (81.2 liter m ⁻² hour ⁻¹ bar ⁻¹ ), antibiotic desalination efficiency (NaCl/tetracycline separation factor of 11.4), antifouling performance, and chlorine resistance.

Aromatic - aliphatic hydrocarbon separation is a challenging but important industrial process. Pervaporation membrane technology has the potential for separating these mixtures. We developed an oriented monolayer polyhedral (OMP) membrane that consists of a monolayer of ordered polyhedral particles and is anchored by hyperbranched polymers. It contains a high density of straight, selective nanochannels, enabling the preferential transport of aromatic molecules. Compared with traditional mixed-matrix membranes with random orientations, the OMP membrane improves the pervaporation separation index for aromatic-aliphatic hydrocarbon mixtures with C ₆ and C ₇ compounds, surpassing the performance of existing membranes by 3 to 10 times. This high performance demonstrates the potential of OMP membranes for hydrocarbon molecular separation and their application in the value-added separation of naphtha feedstocks.