Self-assembled materials are attractive for next-generation membranes. However, the need to align self-assembled nanostructures (e.g. cylinders, lamellae) and the narrow stability windows for ordered bicontinuous systems present serious challenges. We propose and demonstrate a novel approach that circumvents these challenges by exploiting size-selective transport in the water-continuous medium of a nanostructured polymer templated from a self-assembled lyotropic H1 mesophase. Optimization of the mesophase composition enables high-fidelity retention of the H1 structure on photoinduced cross-linking. The resulting material is a mechanically robust nanostructured polymer possessing internally and externally cross-linked nanofibrils surrounded by a continuous aqueous medium. Fabricated membranes show size selectivity at the 1- to 2-nm length scale and water permeabilities of ~10 liters m−2 hour−1 bar−1 μm. Moreover, the membranes display excellent antimicrobial properties due to the quaternary ammonium groups on the nanofibril surfaces. These results represent a breakthrough for the potential use of polymerized lyotropic mesophase membranes in practical water purification applications.

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The encapsulation of fragile biomacromolecules is crucial in many biotechnological applications but remains challenging. Interfacial complexation (IC) in water-in-oil emulsions proves to be an efficient process for the formation of protective polymer layers at the surface of capsuleprecursor water droplets. In this work, the enhancement of conventional IC by introducing thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) strands in the interfacial polymer layer is described. Surfactant-polymer IC is implemented in water-in-fluorocarbon oil emulsions between a watersoluble poly(L-lysine)-g-poly(N-isopropylacrylamide) cationic copolymer (PLL-g-PNIPAM) and an oil-soluble anionic surfactant. Fluorescence imaging demonstrates that the thermal collapse transition of PNIPAM strands, triggered by gentle heating, induces an enrichment of the polymer layer initially formed by IC. Spontaneous co-precipitation of nanoparticles initially dispersed in the aqueous cores-with no specific treatment-is also achieved upon PNIPAM transition. This process is leveraged to irreversibly segregate these nanoparticles in the interfacial polymer layer, resulting in gel-like mixed shells. Thermo-enhancement of conventional IC is thus a promising approach for the straightforward formation, strengthening, and functionalization of capsule shells. As implemented in mild conditions, thermo-enhanced IC is additionally compatible with the encapsulation of proteins, opening new opportunities for delivery systems of biomacromolecules.

Formation of aqueous-core polymer capsules exhibiting an upper critical solution temperature (UCST) was achieved using surfactant–polymer interfacial complexation in water-in-oil inverse emulsions. In fluorinated oil, Coulombic interactions between Krytox, an anionic oil-soluble surfactant, and a cationic poly­(lysine) grafted with poly­(acrylamide-co-acrylonitrile) enabled the formation of an adsorbed polymer shell at the surface of water droplets. The thermoresponsiveness of the polymer shell was assessed by fluorescence microscopy with and without the presence of nanoparticles, including gold particles. We show that, above the cloud point, polymers with a balanced fraction of UCST grafts form flat adlayers that (i) spontaneously entrap nanoparticles upon cooling and (ii) switch from fluid-like dynamics at high temperature to solid-like dynamics below the cloud point. This system offers a straightforward mean to prepare temperature-sensitive capsules in mild, biocompatible conditions and to concentrate nanoparticles (including nanoheaters) in their shell.