Herein, we report an allyl-imidazolium ionic liquid decorated COF and its covalent composite COF@chitosan aerogel, which were shown to be excellent selective CO2 adsorbents and chemical conversion catalysts.
Photoactuators based on liquid crystal elastomers or networks are smart materials that show photoinduced motions. However, their crosslinked networks make their repair or reprocessing difficult. Here, a healable and reprocessable photoactuator is fabricated using entangled high‐molecular‐weight azobenzene‐containing polymers (azopolymers) that are non‐crosslinked. A series of linear liquid crystal azopolymers with different molecular weights are synthesized. The low‐molecular‐weight azopolymers (5–53 kg mol−1) cannot form freestanding photoactuators because their polymer chains lack entanglements, which makes them hard and brittle. In contrast, flexible and stretchable actuators are fabricated using high‐molecular‐weight azopolymers (80–100 kg mol−1) that exhibit good processability because of the polymer chain entanglements. The azopolymer photoactuators show photoinduced bending based on photoinduced trans–cis isomerization of the azopolymers on the irradiated side. The experiments show not only photoinduced phase transitions or changes in the order parameters but also photoinduced solid‐to‐liquid transition of the azopolymers resulting in shape changes and mechanical responses. Thus, photoinduced solid‐to‐liquid transition is a new mechanism for the design of photoactuators. Moreover, the azopolymer photoactuators are healable and reprocessable via solution processing or light irradiation. Healability and reprocessability prolong lifetimes of photoactuators are important for materials reusage and recycling, and represent a new strategy for the preparation of smart materials.
A bifunctional robust and highly porous imidazolium-based ionic liquid decorated UiO-67 type MOF (UiO-67-IL, 1) was successfully constructed via solvothermal assembly of the imidazolium-based ligand and Zr(IV) ions. It exhibits a highly selective adsorption for CO over CH and N. Furthermore, 1 herein can be used as a highly active heterogeneous catalyst for CO cycloaddition with epoxides under atmospheric pressure with or without cocatalyst TBAB (n-BuNBr).
A Pd nano particle (NP)-loaded and nano metal-organic framework (NMOF)-based Pickering emulsifier is reported. The poly[2-(diethylamino)ethyl methacrylate)] (PDEAEMA) chains were grafted onto UiO-66-type NPs via a postsynthetic approach to generate PDEAEMA-g-UiO-66 NMOF (termed as MOF-3). The Pd NPs-loaded Pd@MOF-3 was synthesized via solution impregnation. Stable toluene-in-water Pickering emulsion was prepared with emulsifier Pd@MOF-3. Notably, the obtained Pd@MOF-3 is pH-responsive, and it is able to trigger the emulsification (at neutral condition) and demulsification (at acidic condition) of toluene droplets. Furthermore, it can be a highly active interfacial catalyst to effectively promote one-pot Knoevenagel condensation-hydrogenation cascade reaction at ambient conditions. The pH-responsive property allowed it to be in situ separated and recycled by demulsifying via simply tuning the pH value at the end of the reaction. This smart Pickering emulsion catalytic system is robust, and it can be recycled at least five times without loss of its catalytic activity.
Metal-organic frameworks (MOFs) are widely used as porous materials in the fields of adsorption and separation. However, their practical application is largely hindered by limitations to their processability. Herein, new UiO-66-Urea-based flexible membranes with MOF loadings of 50 (1), 60 (2), and 70 wt % (3) were designed and prepared by post-synthetic polymerization of UiO-66-NH2 nanoparticles and a polyurethane oligomer under mild conditions. The adsorption behavior of membrane 3 towards four hydrophilic dyes, namely, eosin Y (EY), rhodamine B (RB), malachite green (MG), and methylene blue (MB), in aqueous solution was studied in detail. It exhibits strong adsorption of EY and RB but weak adsorption of MG and MB in aqueous solution. Owing to the selective adsorption of these hydrophilic dyes, membrane 3 can remove EY and RB from aqueous solution and completely separate EY/MB, RB/MG, and RB/MB mixtures in aqueous solution. In addition, the membrane is uniformly textured, easily handled, and can be reused for dye adsorption and separation.
Carbon dioxide capture and transformation are of great importance to make cuts in greenhouse gas emissions. Nanometal-organic frameworks (NMOFs) could serve as ideal fillers for polymer membranes owing to their structural diversity and regulable microenvironment of the nanocage. Herein, a bifunctional, robust, and chemically cross-linked NMOF-based membrane was successfully constructed by the postsynthetic polymerization of imidazolium-based ionic liquid (IL)-decorated UiO-66 type nanoparticles (NPs) and the isocyanate-terminated polyurethane oligomer under mild conditions. The IL-modified MOF-polymer membranes exhibit a highly selective adsorption for CO over N and CH. In addition, the obtained membrane can also be a highly active heterogeneous catalyst for CO transformation by cycloaddition with epoxide under an ambient pressure.
Chronic wound infections resulting from severe bacterial invasion have become a major medical threat worldwide. Herein, we report a large-area, homogeneous, and self-standing porphyrin-covalent organic framework (COF)-based membrane with encapsulated ibuprofen (IBU) via an in situ interfacial polymerization and impregnation approach. The obtained IBU@DhaTph-membrane exhibits highly effective antibacterial and anti-inflammatory effects via synergistic light-induced singlet oxygen ( 1 O 2 ) generation and controllable IBU release, which is well supported by in vitro experiments. In addition, the IBU@DhaTph-membrane-based biocompatible "band-aid" type dressing is fabricated, and its excellent anti-infection and tissue remodeling activities are fully evidenced by in vivo chronic wound-healing experiments. This study may inspire and promote the fabrication of many more new types of COF-based multifunctional biomaterials for various skin injuries in clinical medicine.
Pd NP loaded COF-chitosan aerogels with desired shapes can be used to build highly efficient continuous flow-through microreactors to catalyse CB dechlorination in water at room temperature.
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