Molecular Encapsulation Strategy for Precise Membrane Construction
Cucurbit[n]uril (CBn), as a classicalcircular supramolecule, is characterized by a hydrophobic cavity, stronghost-guest effect, strong bonding ability with cations, as well as the functions of molecular switch and nanoreactor, indicating a great potential in optimizing membrane structure and strengthening and enriching membrane functions. (1) The host-guest effect and bonding ability with cations of CBn could solve its insolubility commendably, promoting its application in membranes. (2) The encapsulation for guest molecules by CBn would impede the diffusion of monomer and strengthen the interface polymerization process. (3) The large steric hindrance and hydrophobic cavity would enhance porosity and result in multiple types of fast mass-transfer channels. (4) The sub-nanometer cavity in structure would enrich the membrane functions, such as catalysis, adsorption and so on. All of these would realize the simultaneous improvement of selectivity, permeability, and anti-fouling performance, suggesting a promising future of CBn-based membranes in deep purification of water, chlor-alkali industry, and bio-fuel and other fields.
Nano-encapsulation technology can protect the active monomer from deactivation in harsh environment and release it in specific conditions to maximize the utilization of the monomers, which shows great potential in simplifying the membrane fabrication process, customizing membrane structure, adjusting the membrane performance and industrial applications. (1) Nano-encapsulation technology encapsulates the crosslinker in casting solution and releases them in phase inversion, achieving the one-step construction of asymmetric nanofiltration membrane. (2) Nano-encapsulation technology controlled the interfacial polymerization process to achieve accurate construction of the membrane surface. (3) Nano-encapsulation technology could control the release degree of the monomer to customize the functional membrane suitable for specific applications. The simplified fabrication procedure and customized functional membrane, indicate the great application prospect in bio-pharmaceutical, water resources recovery and scale-up production.
Dual-layer Hollow Fiber Nanofiltration Membranes
Dual-layer hollow fiber membrane concept involves the synchronous construction of hierarchical structure and chemistry consisted in the composite membranes. The dual-layer membrane concept is emerging as a promising membrane candidate. Via deploying materials of desired properties or coupling fabrication methods of distinct strategies, hierarchical characteristics in the dual layers can be individually designed with multiple functionalities. By tailoring the interfacial structure through the established control mechanism, the structural integrity of the dual-layer membranes prevails over traditional composite membranes, securing robust durability and stability in harsh systems and operation conditions. The single-step co-extruded dual-layer membranes with integrated hierarchical structure save the complexity of the multi step coating procedure of traditional composite membranes, which is more time-efficient and cost-effective for the scaling-up fabrication and application.
Smart Nanofiltration Membranes
Smart membranes integrate selective separation and environmental self-adaptive functions by environmental stimulis, such as light, pH, temperature, electricity, or enzyme. Specifically, it is an all-in-one molecular sieve membrane that not only is a single separation barrier transporting specified solutes to pass through but hindering others, but also has additional adaptive properties such as fouling resistance, catalytic degradation, and customized separation to simplify the treatment process and expand the application range of membrane technology incomplex solute separation systems. Moreover, many inherent characteristics including surface charge, pore size, porosity, and surface morphology could be markedly controlled in a controllable and adaptive way by environmental stimuli. The broad application prospects of such membranes would attract widespread attention in chemical synthesis, environmental science, life science, etc.