Abstract
Electrochemical reduction of CO
2
to multi-carbon fuels and chemical feedstocks is an appealing approach to mitigate excessive CO
2
emissions. However, the reported catalysts always show ...either a low Faradaic efficiency of the C
2+
product or poor long-term stability. Herein, we report a facile and scalable anodic corrosion method to synthesize oxygen-rich ultrathin CuO nanoplate arrays, which form Cu/Cu
2
O heterogeneous interfaces through self-evolution during electrocatalysis. The catalyst exhibits a high C
2
H
4
Faradaic efficiency of 84.5%, stable electrolysis for ~55 h in a flow cell using a neutral KCl electrolyte, and a full-cell ethylene energy efficiency of 27.6% at 200 mA cm
−2
in a membrane electrode assembly electrolyzer. Mechanism analyses reveal that the stable nanostructures, stable Cu/Cu
2
O interfaces, and enhanced adsorption of the *OCCOH intermediate preserve selective and prolonged C
2
H
4
production. The robust and scalable produced catalyst coupled with mild electrolytic conditions facilitates the practical application of electrochemical CO
2
reduction.
A coating with programmable multifunctionality based on application requirements is desirable. However, it is still a challenge to prepare a hard and flexible coating with a quick self-healing ...ability. Here, a hard but reversible Si–O–Si network enabled by aminopropyl-functionalized poly(silsesquioxane) and triethylamine (TEA) was developed. On the basis of this Si–O–Si network, basic coatings with excellent transparency, hardness, flexibility, and quick self-healing properties can be prepared by filling soft polymeric micelles into hard poly(silsesquioxane) networks. The highly cross-linked continuous network endows the coating with a hardness (H = 0.83 GPa) higher than those of most polymers (H < 0.3 GPa), while the uniformly dispersed micelles decrease the Young’s modulus (E = 5.89 GPa) to a value as low as that of common plastics, resulting in excellent hardness and flexibility, with an H/E of 14.1% and an elastic recovery rate (W e) of 86.3%. Scratches (∼50 μm) on the coating can be healed within 4 min. The hybrid composition of poly(silsesquioxane) networks also shows great advantages in integration with other functional components to realize programmable multifunctionality without diminishing the basic properties. This nanocomposite design provides a route toward the preparation of materials with excellent comprehensive functions without trade-offs between these properties.
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IJS, KILJ, NUK, PNG, UL, UM
In this work, a different polymer chain structure was synthesized to study π-π interactions between polymer and reduced graphene oxide (RGO). Polymers with different chain structures were obtained ...from free radical copolymerization of styrene with 4-cyanostyrene (containing substituted phenyl rings) and 2-vinylnaphthalene (containing naphthalene rings). In this work, the polystyrene, poly(styrene-
-4-cyanostyrene) and poly(styrene-
-2-vinylnaphthalene) were named as PS, PSCN and PSNP, respectively. RGO was prepared through modified Hummers' method and further thermal reduction, and nanocomposites were prepared by solution blending. Thus, different π-π interactions were formed between polymers and RGO. Raman and thermal gravimetric analysis (TGA) were used to characterize the interfacial interaction, showing that the trend of the interfacial interaction should be in the order of RGO/PSCN, RGO/PS, and RGO/PSNP. The differential scanning calorimetry (DSC) measurement showed that, compared with polymer matrix, the glass transition temperature (T
) of RGO/PS, RGO/PSCN and RGO/PSNP nanocomposites with the addition of 4.0 wt% RGO are increased by 14.3 °C, 25.2 °C and 4.4 °C, respectively. Compared with π-π interaction only formed through aromatic rings, substituent groups changed the densities of electron clouds on the phenyl rings. This change resulted in the formation of donor-acceptor interaction and reinforcement of the π-π interaction at the interface, which leads to increased value of T
. This comparative study can be useful for selecting appropriate interaction groups, as well as suitable monomers, to prepare high performance nanocomposites.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Most plastics originate from limited petroleum reserves and cannot be effectively recycled at the end of their life cycle, making them a significant threat to the environment and human health. ...Closed‐loop chemical recycling, by depolymerizing plastics into monomers that can be repolymerized, offers a promising solution for recycling otherwise wasted plastics. However, most current chemically recyclable polymers may only be prepared at the gram scale, and their depolymerization typically requires harsh conditions and high energy consumption. Herein, it reports less petroleum‐dependent closed‐loop recyclable silica‐based nanocomposites that can be prepared on a large scale and have a fully reversible polymerization/depolymerization capability at room temperature, based on catalysis of free aminopropyl groups with the assistance of diethylamine or ethylenediamine. The nanocomposites show glass‐like hardness yet plastic‐like light weight and toughness, exhibiting the highest specific mechanical strength superior even to common materials such as poly(methyl methacrylate), glass, and ZrO2 ceramic, as well as demonstrating multifunctionality such as anti‐fouling, low thermal conductivity, and flame retardancy. Meanwhile, these nanocomposites can be easily processed by various plastic‐like scalable manufacturing methods, such as compression molding and 3D printing. These nanocomposites are expected to provide an alternative to petroleum‐based plastics and contribute to a closed‐loop materials economy.
Closed‐loop recyclable and less petroleum‐dependent silica‐based nanocomposites with glass‐like hardness, yet plastic‐like lightweight and toughness, as well as anti‐fouling, low thermal conductivity, and flame retardancy, combined with scalable plastic‐like manufacturing methods such as compression molding and 3D printing, promise to be an ideal alternative to plastics and contribute to a circular materials economy in a sustainable future.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
3D printing is becoming a disruptive technology and shows great potential for various practical applications. Specially, digital light processing (DLP) 3D printing demonstrates advantages in high ...resolution and high efficiency. However, extensive production of infusible and insoluble thermosets in DLP printing causes serious resource waste and environmental problems after its disposal. Herein, a reprintable linear polymer is reported for repeatable DLP printing. Taking advantage of the dissolution of linear polymer in its monomer, printed objects can be recycled into liquid resin and reprinted via the same DLP. Polymerization kinetics and printing resolution of recycled resins and mechanical properties of reprinted polymers retain identical as the original. The thermoplastic nature of linear polymer endows 3D objects with welding and reshaping property. Recyclable composites are also successfully fabricated, and sustainable usage of high‐value fillers comes true. This strategy helps to address environmental issues arising from unprocessable thermosets and may contribute to an efficient materials recycling.
A monofunctional monomer is applied in digital light processing (DLP) printing to prepare 3D objects constructed using a linear polymer, which can be converted into resin solution and be reprinted by the same DLP process. The thermoplastic nature of linear polymer offers a way to increase the manufacturing efficiency, reduce the size limitation subjected to the printing area, and achieve efficient materials recycling.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Three-dimensional (3D) printing is becoming a revolutionary technique across various fields. Especially, digital light processing (DLP) 3D printing shows advantages of high resolution and high ...efficiency. However, multifunctional monomers are commonly used to meet the rapid liquid-to-solid transformation during DLP printing, and the extensive production of unreprocessable thermosets will lead to resource waste and environmental problems. Here, we report a family of dynamic polymers with highly tailorable mechanical properties for DLP printing. The dynamic polymers cross-linked by ionic bonding and hydrogen bonding endow printed objects with excellent self-healing and recycling ability. The mechanical properties of printed objects can be easily tailored from soft elastomers to rigid plastics to satisfy practical applications. Taking advantage of the dynamic cross-linking, various assembling categories, including 2D to 3D, small to large 3D structures, and same to different materials assembly, and functional devices with a self-healing capacity can be realized. This study not only helps to address environmental issues caused by traditional DLP-printed thermosets but also realizes the on-demand fabrication of complex structures.
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IJS, KILJ, NUK, PNG, UL, UM
Graphene and polyaniline (PANI) are considered as promising electrode active materials. A rational design of composite structure for graphene and PANI is essential and prerequisite for obtaining ...excellent properties. In this paper, a flexible free-standing reduced graphene oxide (rGO)/PANI nanocomposite film has been successfully prepared through self-assembly and in situ polymerization of anilines in graphene oxide (GO) sheets. Owing to the formation of PANI nanoparticles, the electrochemical capacitance of rGO/PANI nanocomposite film is significantly enhanced. To evaluate electrochemical properties, an all-solid-state flexible supercapacitor is further fabricated through tailoring and assembling the flexible free-standing rGO/PANI nanocomposite film. The nanocomposite film shows high specific capacitance of 0.92 F/cm2 (>1314.3 F/cm3) and its specific capacitance exhibits no obvious fading under bending state or after bending 200 times. The excellent electrochemical performance can be readily ascribed to the synergistic effect between two-dimensional rGO and PANI nanoparticle in the nanocomposite film. This study demonstrates an efficient approach to prepare flexible free-standing active materials for flexible energy storage devices.
•Flexible free-standing rGO/PANI nanocomposite film is prepared.•All-solid-state supercapacitor exhibits superior electrochemical properties.•The excellent performance is ascribed to the synergistic effect between two-dimensional rGO and PANI nanoparticle.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Digital light processing (DLP) 3D printing is advantageous in high printing efficiency and printing resolution for fabricating complex structures across various applications. However, the ...layer‐by‐layer curing manner of DLP leads to weak interlayer adhesion and the anisotropic mechanical properties of printed objects. Here, linear polymers are introduced into commercial resins to weld the interlayer by the diffusion and entanglement of linear polymers after DLP printing via heat treatment. This introduction of linear polymers not only shows a strengthening and toughening effect on the printed objects, but also has no negative impact on the DLP printability. The tensile strengths of objects containing 4.7 wt% polycaprolactone can reach up to ≈500% of that of neat samples in any printing direction. This simple strategy by adding linear polymers into printing resins provides an effective access to prepare DLP printed objects with improved mechanical properties as well as ensure printing resolution and printing efficiency.
Linear polymers with good solubility in resins and not involved in the photopolymerization reaction are introduced into digital light processing 3D printing to ensure high printing efficiency. The interlayer adhesion of printed objects is enhanced via the diffusion and entanglement of linear polymers between layers under heat treatment and thus the mechanical properties are obviously improved.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Magnetic soft robots capable of wirelessly controlled programmable deformation and locomotion are desirable for diverse applications. Such multi‐variable actuation ideally requires a polymer matrix ...with a well‐defined range of softness and stretchability (Young's modulus of 0.1–10 MPa, high stretchability >200%). However, this defined mechanical range excludes most polymer candidates, leaving only a limited number of available polymers (e.g., PDMS, Ecoflex) with covalently cross‐linked networks that may lead to non‐recyclable robots and further potential threats to environment. Herein, based on the synergistic effects of reduced cross‐linking density and intermolecular hydrogen bonding, a dynamic covalent polyimine is newly designed as polymer matrix and magnetic microparticles as fillers, and integrate defined softness and stretchability, full chemical recyclability, rapid room‐temperature healability and multimodal actuation into a single magnetic soft robot. The polyimine is soft and stretchable enough to process soft robots in various geometries by simple laser cutting, without the need to pre‐design the geometry to suit target scenarios. Through a cyclic depolymerization/repolymerization, this full recycling restores 100% of the robots’ mechanical properties and rapid deformability/mobility to their original level within seconds and heals quickly within minutes when damaged, facilitating ideal cyclic material economy for soft robots in diverse scenarios.
Full recyclability, room‐temperature healability, and multimodal rapid actuation capabilities (e.g., bending, twisting, folding/deploying, and rolling locomotion) are effectively integrated into a single magnetic soft robot. Full recyclability allows soft robots to be recycled as raw materials at the end of their life and on‐demand reprocessed into new robots with reprogrammable geometry and functions for further diverse applications.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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