Construction of a Z-scheme heterojunction photocatalyst with oxygen vacancies using cobalt-alumina-layered double hydroxide dispersed between bismuth oxybromide layers for efficient photocatalytic reduction of carbon dioxide.

Under the context of energy shortages and global warming, the photocatalytic reduction of carbon dioxide (CO) to carbon monoxide (CO) using simulated sunlight has attracted considerable research attention. Herein, three-dimensional (3D) Z-scheme cobalt-alumina-layered double hydroxide/bismuth oxybromide (CoAl-layered double hydroxide (LDH)/BiOBr) heterojunction photocatalysts with oxygen vacancies were constructed by intercalating two-dimensional CoAl-LDH between BiOBr layers in the mechanical mixing. The conversion of CO in the water phase was greatly improved compared to CoAl-LDH/BiOBr under 300-W xenon light.

Hydrogen-bonding catalysis of the degradation of polyethylene glycol to 1,4-dioxane over OH-functionalized ionic liquid.

Novel hydrogen-bonding-catalyzed upcycling of polyethylene glycol (PEG) waste to 1,4-dioxane over OH-functionalized ionic liquids (ILs) under mild (≥80 °C), solvent- and metal-free conditions was developed through a theoretical computation-assisted design. Notably, 1,4-dioxane was spontaneously separated due to its immiscibility with ILs.

UV Light-Mediated Hydrolytic Reaction to Develop Magnetic Hydrogel Actuators with Spatially Distributed Ferriferous Oxide Microparticles.

Magnetic hydrogel actuators are developed by incorporating magnetic fillers into the hydrogel matrix. Regulating the distribution of these fillers is key to the exhibited functionalities but is still challenging. Here a facile way to spatially synthesize ferrosoferric oxide (FeO) microparticles in situ in a thermal-responsive hydrogel is reported.

Thermal and Near-Infrared Light-Responsive Hydrogel Actuators with Spatiotemporally Developed Polypyrrole Patterns.

Conjugated polymers are commonly adopted to develop electro- and photoresponsive materials due to their superior electronic conductivity and phototothermal convertibility. However, they are usually homogeneously polymerized within the network, which makes their functionalities challenging to spatiotemporally modulate. In this work, we report a convenient and extensible method to develop polypyrrole patterns in a thermally responsive sodium alginate/poly(-isopropylacrylamide) hydrogel.

Stretching-Induced 2D-to-3D Shape Transformation of an Elastic Composite for Sensitivity-Tailorable Soft Electronics.

The shapes of rubbers and elastomers are challenging to alter, and current methods relying on permanent plasticity and dynamic cross-linking strategies are usually laborious and can inevitably compromise the network elasticity. Here, we report a photoresponsive elastic composite that can be programmed into 3D shapes by first UV light irradiation and then stretching. The composite comprises ethylene propylene rubber as the elastic substrate and photoliquefiable azobenzene small molecules as the responsive filler.

Fabricating 3D Moisture- and NIR Light-Responsive Actuators by a One-Step Gradient Stress-Relaxation Process.

Polymeric materials that can actuate under the stimulation of environmental signals have attracted considerable attention in fields including artificial muscles, soft robotics, implantable devices, etc. To date, the improvement of shape-changing flexibility is mainly limited by their unchangeable shapes and structural and compositional distributions. In this work, we report a one-step treatment process to convert 2D poly(ethylene oxide)/sodium alginate/tannic acid thin films into 3D-shaped moisture- and NIR light-responsive actuators.

Construction of BiWO with double active sites of tunable metallic Bi and oxygen vacancies for photocatalytic oxidation of cyclohexane to cyclohexanone.

Oxygen-containing organics, which are generated from the selective oxidation of their corresponding hydrocarbons, have high value in the chemical and pharmaceutical industries. However, their oxidation reactions are very challenging as the products are more active than the substrates, especially for the oxidation of cyclohexane (CHA). Herein, we focused on the one-step preparation of BiWO with double active sites of tunable metallic Bi and oxygen vacancies (OV-Bi/BiWO) by a facile solvothermal treatment.

Programmable Thermo-Responsive Actuation of Hydrogels via Light-Guided Surface Growth of Active Layers on Shape Memory Substrates.

Hydrogel shape memory and actuating functionalities are heavily pursued and have found great potential in various application fields. However, their combination for more flexible and complicated morphing behaviors is still challenging. Herein, it is reported that by controlling the light-initiated polymerization of active hydrogel layers on shape memory hydrogel substrates, advanced morphing behaviors based on programmable hydrogel shapes and actuating trajectories are realized.

Thermal-Responsive Hydrogel Actuators with Photo-Programmable Shapes and Actuating Trajectories.

Thermal-responsive hydrogel actuators have aroused a wide scope of research interest and have been extensively studied. However, their actuating behaviors are usually monotonous due to their unchangeable shapes and structures. Here, we report thermal-responsive poly(isopropylacrylamide--2-(dimethylamino)ethyl methacrylate)/alginate hydrogels with programmable external shapes and internal actuating trajectories.

Light-Guided Growth of Gradient Hydrogels with Programmable Geometries and Thermally Responsive Actuations.

Hydrogel actuators have gained considerable interest and experienced significant advancements in recent years. However, the programming of their actuating behaviors is still challenging. Herein, we report the development and regulation of gradient structures of hydrogels for programmable thermally responsive actuating behaviors.

Research progress of CO oxidative dehydrogenation of propane to propylene over Cr-free metal catalysts.

CO-assisted oxidative dehydrogenation of propane (CO-ODHP) is an attractive strategy to offset the demand gap of propylene due to its potentiality of reducing CO emissions, especially under the demands of peaking CO emissions and carbon neutrality. The introduction of CO as a soft oxidant into the reaction not only averts the over-oxidation of products, but also maintains the high oxidation state of the redox-active sites. Furthermore, the presence of CO increases the conversion of propane by coupling the dehydrogenation of propane (DHP) with the reverse water gas reaction (RWGS) and inhibits the coking formation to prolong the lifetime of catalysts via the reverse Boudouard reaction.

Photoprogrammable Moisture-Responsive Actuation of a Shape Memory Polymer Film.

Humidity-responsive polymeric actuators have gained considerable interest due to their great potential in the fields including soft robotics, artificial muscles, smart sensors, and actuators. However, most of them can only exhibit invariable shape changes, which severely restricts their further exploration and practical use. Herein, we report that programmable humidity-responsive actuating behaviors can be realized by introducing photoprogrammable hygroscopic patterns into shape memory polymers.

Photo-Dissociable Fe-Carboxylate Coordination: A General Approach toward Hydrogels with Shape Programming and Active Morphing Functionalities.

An extendable double network design for hydrogels with programmable external geometries and actuating trajectories is presented. Chemically cross-linked polyacrylamide as the first network penetrated with linear alginate chains is prepared for demonstration. The coordination of Fe ions with carboxylate groups in alginate chains acts as the second network, and its dissociation through photoreduction is utilized to realize the photoresponsive shape memory property; the shape fixity ratio and shape recovery ratio both exceed 90%.

Controlled direct synthesis of single- to multiple-layer MWW zeolite.

The minimized diffusion limitation and completely exposed strong acid sites of the ultrathin zeolites make it an industrially important catalyst especially for converting bulky molecules. However, the structure-controlled and large-scale synthesis of the material is still a challenge. In this work, the direct synthesis of the single-layer MWW zeolite was demonstrated by using hexamethyleneimine and amphiphilic organosilane as structure-directing agents.

Programmable Humidity-Responsive Actuation of Polymer Films Enabled by Combining Shape Memory Property and Surface-Tunable Hygroscopicity.

Most humidity-responsive polymeric actuators can only exhibit shape transformations between a planar shape in the dry state and a bended three-dimensional (3D) shape when exposed to moisture, and it is challenging to design and prepare hygroscopic actuators with programmable actuating behaviors displayed from sophisticated 3D structures. Herein, we demonstrate that the integration of shape memory property and surface treatment enabled hygromorphic responsivity endows a single-component polymer film with programmable moisture-driven actuating behaviors. The solvent-processed polyethylene--acrylic acid (EAA) copolymer film is soft and stretchable at room temperature, and has a good thermal-responsive shape memory property.

Highly Efficient Oxidative Cyanation of Aldehydes to Nitriles over Se,S,N-tri-Doped Hierarchically Porous Carbon Nanosheets.

Oxidative cyanation of aldehydes provides a promising strategy for the cyanide-free synthesis of organic nitriles. Design of robust and cost-effective catalysts is the key for this route. Herein, we designed a series of Se,S,N-tri-doped carbon nanosheets with a hierarchical porous structure (denoted as Se,S,N-CNs-x, x represents the pyrolysis temperature).

Insight into the Intermolecular Interaction and Free Radical Polymerizability of Methacrylates in Supercritical Carbon Dioxide.

High pressure in situ Fourier transfer infrared/near infrared technology (HP FTIR/NIR) along with theoretical calculation of density functional theory (DFT) method was employed. The solvation behaviors and the free radical homopolymerization of methyl methacrylate (MMA), methacrylate acid (MAA), trifluoromethyl methacrylate (MTFMA) and trifluoromethyl methacrylate acid (TFMAA) in scCO were systematically investigated. Interestingly, the previously proposed mechanism of intermolecular-interaction dynamically-induced solvation effect (IDISE) of monomer in scCO is expected to be well verified/corroborated in view that the predicted solubility order of the monomers in scCO via DFT calculation is ideally consistent with that observed via HP FTIR/NIR.

Photoresponsive Shape Memory Hydrogels for Complex Deformation and Solvent-Driven Actuation.

A new design for photoresponsive shape memory hydrogels and their possible applications are demonstrated in the present study. We show that the photodissociable Fe-carboxylate coordination can be utilized as a molecular switch to realize photocontrol of shape memory on both macroscopic and microscopic scales and enable a number of functions. Indeed, Fe-carboxylate coordination can fix a large tensile strain (up to 680%) of the sodium alginate/polyacrylamide hydrogel through cross-linking of sodium alginate chains, and subsequent UV irradiation allows strain energy release in spatially selected regions through reduction of Fe to Fe.

Controlled 3D Shape Transformation Activated by Room Temperature Stretching and Release of a Flat Polymer Sheet.

Shape transformation of polymeric materials, including hydrogels, liquid crystalline, and semicrystalline polymers, can be realized by exposing the shape-changing materials to the effect of a variety of stimuli such as temperature, light, pH, and magnetic and electric fields. Herein, we demonstrate a novel and different approach that allows a flat sheet or strip of a polymer to transform into a predesigned 3D shape or structure by simply stretching the polymer at room temperature and then releasing it from the external stress, that is, a 2D-to-3D shape change is activated by mechanical deformation under ambient conditions. This particular type of stimuli-controlled shape-changing polymers is based on suppressing plastic deformation in selected regions of the flat polymer sheet prior to stretching and release.

CO-Acidolysis of iminoboronate ester based polymersomes.

Due to the very weak acidity of CO in water, it is highly interesting to fabricate CO-responsive polymersomes which have both CO-protonatable tertiary amines and CO-hydrolyzable iminoboronate-linked drugs. Upon CO addition, amine protonation and iminoboronate hydrolysis simultaneously occur, leading to prominent vesicle disassembly and a tunable release feature.

2D-to-3D Shape Transformation of Room-Temperature-Programmable Shape-Memory Polymers through Selective Suppression of Strain Relaxation.

Although shape-memory polymers (SMPs) can alter their shapes upon stimulation of environmental signals, complex shape transformations are usually realized by using advanced processing technologies (four-dimensional printing) and complicated polymer structure design or localized activation. Herein, we demonstrate that stepwise controlled complex shape transformations can be obtained from a single flat piece of SMP upon uniform heating. The shape-memory blends prepared by solution casting of poly(ethylene oxide) and poly(acrylic acid) (PAA) exhibit excellent mechanical and room-temperature shape-memory behaviors, with fracture strain beyond 800% and both shape memory and shape recovery ratio higher than 90%.

Controlling CO -Responsive Behaviors of Polymersomes Self-Assembled by Coumarin-Containing Star Polymer via Regulating Its Crosslinking Pattern.

An oligo(ethylene glycol)-based star polymer of N -(OEG-C) with fluorescent coumarin as hydrophobic end groups and dual tertiary amines as the star center is designed and synthesized. Owing to its amphiphilic nature of N -(OEG-C) , it will self-assemble into hollow vesicles with coumarin groups dispersed in the hydrophobic membrane and exhibits CO -responsive behavior due to the protonation of amine centers with CO . More importantly, coumarin moieties can either form non-crosslinking with γ-cyclodextrin via the 2/1 host-guest inclusion, or covalently photodimerized by 365 nm light, offering a tunable crosslinking pattern in the hydrophobic membrane and thus adjusting its CO -stimulated reorganization and disassembly behaviors of these vesicles in aqueous solution.

Impact of the acidic group on the hydrolysis of 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione.

The hydrolysis mechanism and the kinetics of using 2-dinitromethylene-5,5-dinitropyrimidine-4,6-dione (NMP) to prepare the representative insensitive energetic material 1,1-diamino-2,2-dinitroethylene (FOX-7) in a nitric-sulfuric acid system are systematically investigated a density functional theory (DFT) method. The impact of the co-existing acidic group of HSO as well as the solvent effects of the mixed acids on the hydrolysis of NMP are elucidated and discerned, and the proposed catalysis and promotion of the hydrolysis of NMP with HSO are verified. The HSO -catalyzed hydrolysis pathway is more favorable than the direct pathway as well as the HO-catalyzed hydrolysis, indicating that HSO may be a promising catalyst for the preparation of FOX-7 in a mixed acid system.