Autonomous Interfacial Assembly of Polymer Nanofilms via Surfactant-Regulated Marangoni Instability

"Like Dissolves Like" Strategy Facilitates Interfacial Polymerization for Facile Synthesis of Highly Permeable Reverse Osmosis Membranes

Existing reverse osmosis (RO) membranes often feature a polyamide rejection layer fabricated by interfacial polymerization (IP) between m-phenylenediamine (MPD) and trimesoyl chloride. However, polyamide RO membrane formation is limited by the poorly soluble polar MPD in the nonpolar organic solvent (e.g., hexane). Herein, we developed a dual organic solvent system to increase MPD solubility via introducing a polar solvent of dioxane into the hexane as inspired by the classical "like dissolves like" theory and thus promoting the IP reaction efficiency. Consequently, the optimal RO membrane exhibited a superior desalination performance with a rejection of 99.2% for 35,000 ppm of NaCl, simultaneous with a high water permeance of 3.1 L m-2 h-1 bar-1. Meanwhile, it had a boron rejection of 90.3% that far exceeds commercial RO membranes. These findings demonstrate that a dual organic solvent IP system can offer a facile yet effective strategy for scalable fabrication of high-performance RO membranes.

Interfacially Assembled Anion Exchange Membranes for Water Electrolysis

High-performance and durable anion exchange membranes (AEMs) are critical for realizing economical green hydrogen production through alkaline water electrolysis (AWE) or AEM water electrosysis (AEMWE). However, existing AEMs require sophisticated fabrication protocols and exhibit unsatisfactory electrochemical performance and long-term durability. Here we report an AEM fabricated via a one-pot, in situ interfacial Menshutkin reaction, which assembles a highly cross-linked polymer containing high-density quaternary ammoniums and nanovoids inside a reinforcing porous support. This structure endows the membrane with high anion-conducting ability, water uptake (but low swelling), and mechanical and thermochemical robustness. Consequently, the assembled membrane achieves excellent AWE (0.97 A cm-2 at 1.8 V) and AEMWE (5.23 A cm-2 at 1.8 V) performance at 5 wt % KOH and 80 °C, significantly exceeding that of commercial and previously developed membranes, and excellent long-term durability. Our approach provides an effective method for fabricating AEMs for various energy and environmental applications.

Structures of Liquid-Liquid Interfaces in Partially Miscible Systems Revealed by Soft X-ray Imaging

The properties of liquid-liquid interfaces are intricately linked to its structure, with a particular focus on the concentration distribution within the interface. To obtain precise information regarding the concentration distribution, we have developed a high-resolution soft X-ray imaging method for liquid-liquid interfaces. This work focused on representative partially miscible systems, analyzing the interfacial concentration distribution profiles of water-alkanols under both steady-state and dynamic processes, and obtaining the diffusion coefficients of different water concentrations in alkanols. Significant disparities in concentration distributions and the concentration-related diffusion coefficients were observed despite comparable diffusion distances within the same system across different states. Meanwhile, it was found that alkanols exhibit adsorption phenomena at the interface. This newfound knowledge serves as a crucial stepping stone toward a deeper understanding of partially miscible systems. Our study opens a way to explore liquid-liquid interface information with high-resolution.

Empowering ultrathin polyamide membranes at the water-energy nexus: strategies, limitations, and future perspectives

Membrane-based separation is one of the most energy-efficient methods to meet the growing need for a significant amount of fresh water. It is also well-known for its applications in water treatment, desalination, solvent recycling, and environmental remediation. Most typical membranes used for separation-based applications are thin-film composite membranes created using polymers, featuring a top selective layer generated by employing the interfacial polymerization technique at an aqueous-organic interface. In the last decade, various manufacturing techniques have been developed in order to create high-specification membranes. Among them, the creation of ultrathin polyamide membranes has shown enormous potential for achieving a significant increase in the water permeation rate, translating into major energy savings in various applications. However, this great potential of ultrathin membranes is greatly hindered by undesired transport phenomena such as the geometry-induced "funnel effect" arising from the substrate membrane, severely limiting the actual permeation rate. As a result, the separation capability of ultrathin membranes is still not fully unleashed or understood, and a critical assessment of their limitations and potential solutions for future studies is still lacking. Here, we provide a summary of the latest developments in the design of ultrathin polyamide membranes, which have been achieved by controlling the interfacial polymerization process and utilizing a number of novel manufacturing processes for ionic and molecular separations. Next, an overview of the in-depth assessment of their limitations resulting from the substrate membrane, along with potential solutions and future perspectives will be covered in this review.

Interfacial Self-Assembly of Oriented Semiconductor Monolayer for Chemiresistive Sensing

Semiconductor nanofilm fabrication with advanced technology is of great importance for next-generation electronics/optoelectronics. Fabrication of high-quality and perfectly oriented semiconductor thin films and integration into high-performance electronic devices with low cost and high efficiency are huge challenges. Here we exquisitely utilized the Marangoni effect to perfectly guide tin disulfide (SnS2) nanocoins into an ordered assembly in milliseconds, resulting in an uniaxial-oriented monolayer semiconductor film. Further exploration revealed that the formed "crumple zone" at the interface caused by the Marangoni force endows the nanofilm with a rapid healable capability, which can be easily transferred to arbitrary substrates. As a proof of concept, the nanocoin-monolayer was transferred onto a micro-interdigitated electrode substrate to form a high-performance chemiresistive sensor that can effectively monitor the trace amounts of toxic gases. In addition, the assembled monolayer nanofilms can be conformally printed on freeform surfaces: both flat and nonflat substrates. This efficient and low-cost Marangoni force-assisted surface self-assembly (MFA-SSA) strategy is promising for advanced microelectronics and real industrial applications.