As one of the main forms and intermediate carriers of energy, it is impressive to expand the application scope of heat energy, thereby boosting innovations in heat harvesting, conversion, storage, ...regulation, and utilization associated with the relevant techniques. Phase change materials (PCMs), as a state‐of‐the‐art latent heat storage technique, have garnered increasing interest in heat‐related applications over the past decades, and abundant high‐performance PCMs with excellent shape stability and salient thermal conductivity have been developed. This review focuses on the issues concerning organic PCMs from the perspectives of flexible, multifunctional, and smart phase change composites, along with emerging applications and processing technologies, which are expected to offer possible guidance for the exploration of next‐generation advanced functional phase change composites.
Next‐generation advanced functional phase change composites are analyzed from the perspectives of myriad phase change materials, promising applications, and mass‐manufactured processing technologies to boost their rapid implementation.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•Encoding strategy reduces optimization dimensionality.•Three-layer nested approach increases hybrid system’s energy production.•Proposed generation schedules provide robust and effective operating ...decisions.
Joint operation of large-scale renewable energy sources (e.g., hydro and solar) has become a trend in modern power systems, and more operators of existing hydropower reservoir systems are adopting it. This study aimed to improve guidance for the daily generation scheduling of a large hydro–photovoltaic (PV) power plant. First, a robust optimization model that accounts for uncertain PV power generation was formulated, in which the delivered power output of the hybrid system and hydro unit status are robust decision variables. To deal with the complexity of the model solution, a three-layer nested framework was proposed to solve the generation scheduling problem in a hierarchical structure. In the outer layer, a direct search algorithm optimizes the delivered power output of the system, aiming to maximize energy production while satisfying specified load characteristics. In the middle and inner layers, a cuckoo search algorithm and dynamic programming technique optimize the hydro unit status and load dispatch strategies, respectively, with the objective of minimizing water consumption. Finally, a decision interval on delivered power output of the system was derived by relaxing the load characteristic constraint. Results for a case study using China’s Longyangxia hydro–PV power plant indicated that the robust optimization model and the three-layer nested approach could provide effective power generation plans for the hybrid system within a reasonable time. Compared with actual operation, the power generation plans could increase energy production of the hybrid system by 1.9% while decreasing total online time of the hydro units by 9.7%. Therefore, the proposed method could improve guidance for the hydro–PV power plant’s generation scheduling. In practice, conjunctive use of the power generation plan and the decision interval could also inform flexible decision-making for plant operations management.
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GEOZS, IJS, IMTLJ, KISLJ, NLZOH, NUK, OILJ, SAZU, SBCE, UL, UM, UPCLJ, UPUK
Difunctionalization: Inexpensive and environmentally benign FeCl3 catalyzes the oxidative 1,2‐alkylarylation of activated alkenes with an aryl C(sp2)H bond and a C(sp3)H bond adjacent to a ...heteroatom. This reaction is a new strategy for the synthesis of oxindoles and makes use of DBU as ligand and TBHP as oxidant (see scheme, TBHP=tert‐butyl hydrogenperoxide).
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A rhodium(III)‐catalyzed 3+2/5+2 annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with internal alkynes is presented. This transformation provides straightforward access to indeno1,7‐cdazepine ...architectures through a sequence involving the formation of a rhodium(III) azavinyl carbene, dual C(sp2)H functionalization, and 3+2/5+2 annulation.
A quantum leap in complexity: A general strategy based on rhodium(III) azavinyl carbene intermediates was established for the oxidative 3+2/5+2 annulation of 4‐aryl 1‐tosyl‐1,2,3‐triazoles with alkynes. This general method provided densely functionalized indeno1,7‐cdazepine architectures with excellent selectivity through the functionalization of two C(sp2)H bonds (see scheme; Cp*=pentamethylcyclopentadienyl, Ts= p‐toluenesulfonyl).
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•Phase change hydrogel was prepared by integrating PW microspheres in PVA-hydrogel.•PVA-hydrogel endows the composite with great flexibility and adaptivity.•The interfaces lead to ...lower thermal conductivity/infrared transmittance.•Phase change hydrogel present infrared stealth effect in the mid-/low- temperature.
Infrared stealth technology capable of effectively rendering targets invisible to thermal infrared detectors plays an important role in defense industry and modern military. Therefore, developing novel infrared stealth materials has aroused widespread concern. Phase change materials (PCMs) with thermal storage and management capabilities can modulate temperature to hide infrared radiation, providing a plausible alternative to the rational design of infrared stealth materials. Herein, flexible phase change hydrogels with excellent mechanical and thermophysical properties are fabricated by integrating the hydrogel substrate with phase change microspheres. Owing to the interfacial effect originating from the introduction of the microspheres, the thermal conductivity and the infrared transmittance of the resulting phase change hydrogel are reduced to 0.17 W/(mK) and 0.3%, respectively, enabling the phase change hydrogel to achieve an intriguing infrared stealth function for targets in the mid-/low-temperature range (-20–60 °C). In addition to conforming to arbitrary targets owing to its excellent flexibility and adaptability, the phase change hydrogel can be facilely coated on common fabrics to yield phase change wearable devices, attaining the on-body infrared stealth. This work offers a constructive guidance to prepare high-performance flexible PCMs for emerging infrared stealth applications.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The oxidative interception of various σ‐alkyl palladium(II) intermediates with additional reagents for the difunctionalization of alkenes is an important research area. A new palladium‐catalyzed ...oxidative difunctionalization reaction of alkenes with α‐carbonyl alkyl bromides is described, in which the σ‐alkyl palladium(II) intermediate is generated through a Heck insertion and trapped using an aryl C(sp2)H bond. This method can be applied to various α‐carbonyl alkyl bromides, including primary, secondary, and tertiary α‐bromoalkyl esters, ketones, and amides.
Indolinone synthesis: A new palladium‐catalyzed oxidative difunctionalization reaction of N‐arylalkenes with primary, secondary, and tertiary α‐carbonyl alkyl bromides proceeds through a radical process and provides indolin‐2‐ones in moderate to excellent yields. The reaction is initiated by a Heck insertion followed by interception of the σ‐alkyl palladium(II) intermediate with aryl C(sp2)H bonds. dppe=1,2‐bis(diphenylphosphino)ethane.
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Cellulose is one of the most promising fillers used for poly(lactic acid) (PLA) composites owing to its natural abundance, complete biodegradability, and superb properties. Improving the ...compatibility between hydrophilic cellulose and hydrophobic PLA is a hot topic in literature for a long time, wherein surface chemical modification of cellulose have attracted the most attention. In this review, we summarized the research activities of recent five years that focus on the chemical modification strategies of cellulose used in PLA/cellulose composites. Two major classifications are carefully discussed, i.e., the reactions of small molecules modified cellulose such as esterification, oxidation/amidation and silanization, and reactions of polymers modified cellulose including PLA and other polymers. The discussion mainly focuses on the relationship between the structure of grafted small molecule/polymers and mechanical properties of PLA composites and addresses the current common problems that hinder the chemical modified cellulose from developing high-performance PLA/cellulose composites. We hope this review provide some possible inspiration for researchers to develop PLA/cellulose products with industrial value in the future.
•Latest progresses on cellulose surface modification for PLA/cellulose composites are reviewed.•Small molecule modified cellulose is discussed in terms of esterification, oxidation/amidation and silanization.•Fabrication of polymer grafted cellulose by PLA and other polymers are discussed.•Relationship between structures of cellulose and mechanical properties of PLA/cellulose composites is highlighted.•Current challenges and perspectives for developing high-performance PLA/cellulose composites are discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
A new, efficient Cu-catalyzed intramolecular C−H oxidation/acylation method has been developed for the synthesis of substituted indoline-2,3-diones (isatins). In the presence of CuCl2 and O2, a ...variety of formyl-N-arylformamides underwent the tandem reaction to afford the corresponding indoline-2,3-diones in moderate to good yields. It is noteworthy that the reaction serves as the first example of transition-metal-catalyzed transformation for the preparation of indoline-2,3-diones.
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This study describes a new rhodium(III)‐catalyzed 3+2 annulation of 5‐aryl‐2,3‐dihydro‐1H‐pyrroles with internal alkynes using a Cu(OAc)2 oxidant for building a spirocyclic ring system, which ...includes the functionalization of an aryl C(sp2)H bond and addition/protonolysis of an alkene CC bond. This method is applicable to a wide range of 5‐aryl‐2,3‐dihydro‐1H‐pyrroles and internal alkynes, and results in the assembly of the spiroindene‐1,2′‐pyrrolidine architectures in good yields with excellent regioselectivities.
Spiral bound: A new 3+2 annulation route to spiroindene‐1,2′‐pyrrolidines includes C(sp2)H functionalization, insertion of an alkyne, addition of a CC bond, and protonolysis to assemble a spirocyclic ring system. The method has a broad range of functional‐group tolerance and excellent regioselectivity. Ts=4‐toluenesulfonyl.
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•A novel CNC hydrogel is prepared though UV-induced thiol-ene click chemistry.•Solvent-exchange strategy is used innovatively to fabricate PEG/CNC hybrid PCMs.•The hybrid PCMs ...exhibits high latent heat and excellent shape stability.•This work proposes a potential strategy for large-scale manufacture of PCMs.
How to realize large-scale manufacture of phase change materials (PCMs) with high latent heat storage and excellent shape stability is still a great challenge. Recently, encapsulating PCMs with three-dimensional porous structure is of great interest due to its excellent leak-proof ability and large latent heat storage capacity. However, the conventional fabrication techniques of 3D supporting skeletons for loading PCMs commonly involves hydrothermal process, freeze-drying and vacuum impregnation, which is difficult to operate and costly for large-scale manufacture. Herein, a facile and novel strategy for the potential large-scale manufacture of 3D porous structure supported PCMs is presented. This strategy involves two steps: rapid preparation of a novel CNC hydrogel based on UV-induced thiol-ene click chemistry and direct impregnation of PEG PCMs into the CNC hydrogel using solvent-exchange strategy for the first time. The structure and properties of CNC hydrogels and PEG/CNC hybrid PCMs are characterized. High latent heat, improved thermal conductivity, excellent thermal and shape stability are observed in the PEG/CNC hybrid PCMs. An obvious decrease of the crystalline phase change temperature is also observed due to the strong hydrogen bonding between the well reserved CNC nanofiber network and PEG molecule chains. This solvent-exchange strategy shows great potential in the large-scale manufacture of high-performance and shape-stable PCMs.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
