Polymeric Microcapsules as Robust Mimics of Emulsion Liquid Membranes for Selective Ion Separations.

Selective ion separations are increasingly needed to combat water scarcity, recover resources from wastewater, and enable the efficient recycling of electronics waste. Emulsion liquid membranes (ELMs) have received interest due to rapid kinetics, high selectivities, and low solvent requirements but are too unstable for industrial usage. We demonstrate that polymeric microcapsules can serve as robust, solvent-free mimics of ELMs.

Functionalized Polymersomes from a Polyisoprene-Activated Polyacrylamide Precursor.

Self-assembled polymer nanoparticles have tremendous potential in biomedical and environmental applications. For all applications, tailored polymer chemistries are critical. In this study, we demonstrate a precursor approach in which an activated, organic solvent-soluble block polymer precursor is modified through mild postpolymerization modifications to access new polymer structures.

Next-Generation Ultrafiltration Membranes Enabled by Block Polymers.

Reliable and equitable access to safe drinking water is a major and growing challenge worldwide. Membrane separations represent one of the most promising strategies for the energy-efficient purification of potential water sources. In particular, porous membranes are used for the ultrafiltration (UF) of water to remove contaminants with nanometric sizes.

Ionization behavior of nanoporous polyamide membranes.

Escalating global water scarcity necessitates high-performance desalination membranes, for which fundamental understanding of structure-property-performance relationships is required. In this study, we comprehensively assess the ionization behavior of nanoporous polyamide selective layers in state-of-the-art nanofiltration (NF) membranes. In these films, residual carboxylic acids and amines influence permeability and selectivity by imparting hydrophilicity and ionizable moieties that can exclude coions.

Co-Casting Highly Selective Dual-Layer Membranes with Disordered Block Polymer Selective Layers.

Highly selective and water permeable dual-layer ultrafiltration (UF) membranes comprising a disordered poly(methyl methacrylate--styrene)--poly(lactide) selective layer and a polysulfone (PSF) support layer were fabricated using a co-casting technique. A dilute solution of diblock polymer was spin coated onto a solvent-swollen PSF layer, rapidly heated to dry and disorder the block polymer layer, and subsequently immersed into an ice water coagulation bath to kinetically trap the disordered state in the block polymer selective layer and precipitate the support layer by nonsolvent-induced phase separation. Subsequent removal of the polylactide block generated porous membranes suitable for UF.

Pathways and Challenges for Biomimetic Desalination Membranes with Sub-Nanometer Channels.

Transmembrane protein channels, including ion channels and aquaporins that are responsible for fast and selective transport of water, have inspired membrane scientists to exploit and mimic their performance in membrane technologies. These biomimetic membranes comprise discrete nanochannels aligned within amphiphilic matrices on a robust support. While biological components have been used directly, extensive work has also been conducted to produce stable synthetic mimics of protein channels and lipid bilayers.

Capillary-driven desalination in a synthetic mangrove.

According to the cohesion-tension theory, mangrove trees desalinate salty water using highly negative pressure (or tension) that is generated by evaporative capillary forces in mangrove leaves. Here, we demonstrate a synthetic mangrove that mimics the main features of the natural mangrove: capillary pumping (leaves), stable water conduction in highly metastable states (stem), and membrane desalination (root). When using nanoporous membranes as leaves, the maximum osmotic pressures of saline feeds (10 to 30 bar) allowing pure water uptake precisely correspond to expected capillary pressures based on the Young-Laplace equation.

Monte Carlo Simulations of Framework Defects in Layered Two-Dimensional Nanomaterial Desalination Membranes: Implications for Permeability and Selectivity.

Two-dimensional nanomaterial (2-D NM) frameworks, especially those comprising graphene oxide, have received extensive research interest for membrane-based separation processes and desalination. However, the impact of horizontal defects in 2-D NM frameworks, which stem from nonuniform deposition of 2-D NM flakes during layer build-up, has been almost entirely overlooked. In this work, we apply Monte Carlo simulations, under idealized conditions wherein the vertical interlayer spacing allows for water permeation while perfectly excluding salt, on both the formation of the laminate structure and molecular transport through the laminate.

A Path to Ultraselectivity: Support Layer Properties To Maximize Performance of Biomimetic Desalination Membranes.

Reverse osmosis (RO) has become a premier technology for desalination and water purification. The need for increased selectivity has incentivized research into novel membranes, such as biomimetic membranes that incorporate the perfectly selective biological water channel aquaporin or synthetic water channels like carbon nanotubes. In this study, we consider the performance of composite biomimetic membranes by projecting water permeability, salt rejection, and neutral-solute retention based on the permeabilities of the individual components, particularly the water channel, the amphiphilic bilayer matrix, and potential support layers that include polymeric RO, nanofiltration (NF), and porous ultrafiltration membranes.

Permselectivity limits of biomimetic desalination membranes.

Water scarcity and inadequate membrane selectivity have spurred interest in biomimetic desalination membranes, in which biological or synthetic water channels are incorporated in an amphiphilic bilayer. As low channel densities (0.1 to 10%) are required for sufficient water permeability, the amphiphilic bilayer matrix will play a critical role in separation performance.

Enhanced antibacterial activity through the controlled alignment of graphene oxide nanosheets.

The cytotoxicity of 2D graphene-based nanomaterials (GBNs) is highly important for engineered applications and environmental health. However, the isotropic orientation of GBNs, most notably graphene oxide (GO), in previous experimental studies obscured the interpretation of cytotoxic contributions of nanosheet edges. Here, we investigate the orientation-dependent interaction of GBNs with bacteria using GO composite films.

Analysis of 2,2'-azobis (2-amidinopropane) dihydrochloride degradation and hydrolysis in aqueous solutions.

2,2'-Azobis(2-amidinopropane) dihydrochloride (AAPH), a free radical-generating azo compound, is gaining prominence as a model oxidant in small molecule and protein therapeutics, namely for its ability to initiate oxidation reactions via both nucleophilic and free radical mechanisms. To better understand its degradation pathways, AAPH was degraded at 40°C in aqueous solutions over a wide pH range. Samples were analyzed via liquid chromatography-ultraviolet spectroscopy and liquid chromatography-tandem mass spectrometry (LC-MS/MS).