The identification of highly active heterogeneous catalysts to replace their homogeneous counterparts remains a challenge in the case of organic catalysts, especially polymers, in highly viscous reaction systems. In t...The identification of highly active heterogeneous catalysts to replace their homogeneous counterparts remains a challenge in the case of organic catalysts, especially polymers, in highly viscous reaction systems. In this work, we designed and synthesized a novel, solid-supported, and heterogeneous pseudo-single atom Pt catalyst with high activity and recyclability. Superparamagnetic Fe3O4-SiO2 core--shell nanoparticles （NPs） were used as the substrate. The functionalization of the SiO2 shell with silane coupling agents containing vinyl groups allows stabilizing Pt on the SiO2 surface through complexation. The as-prepared pseudosingle atom Pt displays high activity in the hydrosilylation of allyl-terminated polyether with polymethylhydrosiloxane and could be easily collected by applying a magnetic field. The Pt/vinyl/SiO2/Fe3O4 catalyst can be reused for up to four reaction cycles without appreciable decrease in activity. This work demonstrates a novel strategy for the design of pseudo-single atom noble metal catalysts for processes in high-viscosity media.展开更多
Utilizing plasmonic nano-particles/structures for solar water evaporation has aroused increasing interest; however, large-scale methods are desired to boost the efficiency and improve the practicality of solar steam g...Utilizing plasmonic nano-particles/structures for solar water evaporation has aroused increasing interest; however, large-scale methods are desired to boost the efficiency and improve the practicality of solar steam generation. We developed a membrane-supported floating solar steam generation system based on graphene oxide and a multiscale plasmonic nanostructure; the latter is a micrometer-sized colloidosome that was assembled from hollow and porous Ag/Au nanocubes. By taking advantage of multiscale plasmonic coupling of the particles, an extremely high solar thermal conversion efficiency up to 92% at 10 kW·m^-2 （with a water evaporation rate reaching 12.96 kg·m^-2·h^-1） can be achieved. The TiO2 nanoparticle-modified floating system is also capable of high-efficiency dye degradation in organic-polluted water, rendering such a membrane system recyclable and scalable for practical and versatile solar-driven generation of clean water.展开更多
Traditional flame-retardant plastics are technically difficult to chemically recycle.The development of newtypes of flame-retardant plastics that are intrinsically capable of being closed-loop recycled and are suffici...Traditional flame-retardant plastics are technically difficult to chemically recycle.The development of newtypes of flame-retardant plastics that are intrinsically capable of being closed-loop recycled and are sufficiently robust and stable to satisfy their practical application is urgently needed.In this study,closed-loop recyclable flame-retardant plastics with high mechanical strength and excellent chemical resistance are fabricated by cross-linking amino-terminated polyimide(PI-NH_(2))and aldehyde-terminated cyclophosphazene(CP-CHO)with imine bonds.The resultant flame-retardant plastic,which is denoted as PI-CP,exhibits a tensile strength of∼115.6 MPa,Young’s modulus of∼2.5 GPa,and glass transition temperature of 316°C.In the PI-CP plastic,the imine bonds are isolated within hydrophobic microenvironments generated by the rigid and hydrophobic polyimide chains and the benzene ring of cyclophosphazenes.As a result,the PI-CP plastics are highly stable in highly acidic and basic aqueous solutions and other commonly used organic solvents.The PI-CP plastic shows outstanding flame retardancy with a limiting oxygen index value of 48.8%.More importantly,the PI-CP plastic can be depolymerized to generate the original PI-NH_(2)and CPCHO monomers in high yields(∼97%)and purity.The recovered monomers can be used to refabricate the original plastics,establishing highly efficient polymer-monomer-polymer circulation and a sustainable plastics economy.展开更多
Concrete-filled rectangular steel tubular(CFRST)composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab.This new type of bridge has the advantages of high structural force-tr...Concrete-filled rectangular steel tubular(CFRST)composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab.This new type of bridge has the advantages of high structural force-transferring efficiency,rapid assembly construction speed and excellent total life cycle,which meets the construction concept of green,recyclable and sustainable development.Due to the broad application prospects,experiment on the flexural behavior of CFRST composite truss bridge in the negative moment region was reported by authors previously.This paper thus presents a finite element analysis(FEA)modelling verified by the reported test data to further investigate the detailed analytical behavior of this structure.The structural response and failure mechanism of CFRST composite truss beam in the negative moment region are studied.In addition,the important structural design parameters on the flexural performance of the CFRST composite truss beam are also investigated,including the height to span ratio,the brace-to-chord wall thickness ratio,the reinforcement ratio of steel reinforcements and prestressed tendons and the strength grade of concrete infill in chords.Finally,the reasonable structural design parameters range are proposed for the optimum design of the CFRST composite truss bridge.展开更多
A self-healing and recyclable carbon tube/epoxy adhesive was prepared by epoxy monomer with Diels-Alder （DA） bonds, diethylenetriamine and polyethyleneimine modified multi-wall carbon nanotubes （MWCNTs）. The self-...A self-healing and recyclable carbon tube/epoxy adhesive was prepared by epoxy monomer with Diels-Alder （DA） bonds, diethylenetriamine and polyethyleneimine modified multi-wall carbon nanotubes （MWCNTs）. The self-healing and recyclable ability was attained by thermally reversible Diels-Alder reaction between furan and maleimide in the epoxy monomer. By controlling the molar ratio of furfuryl glycidyl ether and 4,4＇-methylenebis（N-phenylmaleimide）, the glass transition temperature and mechanical properties of MWCNTs/epoxy adhesives were varied. The self-healing properties of MWCNTs/epoxy polymers were evaluated by lap shear experiment and the results showed that the MWCNTs/epoxy adhesives exhibited enhanced mechanical properties and excellent self-healing ability under heat stimulus. The healing efficiency was related to the molecule mobility and the conversion of DA reaction between furan and maleimide. The MWCNTs/epoxy adhesives also displayed excellent recyclable ability by transforming into soluble polymer under heating. These materials offer a wide range of possibilities to produce materials with healing and recyclable ability and have the potential to bring great benefits to our daily lives by enhancing the safety, performance, and lifetime of products.展开更多
基金This work is partially supported by the National Natural Science Foundation of China （No. 21303265） and Ph.D. Programs Foundation of Ministry of Education of China （No. 20130007120012）.
文摘The identification of highly active heterogeneous catalysts to replace their homogeneous counterparts remains a challenge in the case of organic catalysts, especially polymers, in highly viscous reaction systems. In this work, we designed and synthesized a novel, solid-supported, and heterogeneous pseudo-single atom Pt catalyst with high activity and recyclability. Superparamagnetic Fe3O4-SiO2 core--shell nanoparticles （NPs） were used as the substrate. The functionalization of the SiO2 shell with silane coupling agents containing vinyl groups allows stabilizing Pt on the SiO2 surface through complexation. The as-prepared pseudosingle atom Pt displays high activity in the hydrosilylation of allyl-terminated polyether with polymethylhydrosiloxane and could be easily collected by applying a magnetic field. The Pt/vinyl/SiO2/Fe3O4 catalyst can be reused for up to four reaction cycles without appreciable decrease in activity. This work demonstrates a novel strategy for the design of pseudo-single atom noble metal catalysts for processes in high-viscosity media.
基金This work was financially supported by the National Natural Science Foundation of China （Nos. 21475125 and 21175125）, the Hundred Talents Program of the Chinese Academy of Sciences, and the State Key Laboratory of Electroanalyfical Chemistry （No. 110000R387）.
文摘Utilizing plasmonic nano-particles/structures for solar water evaporation has aroused increasing interest; however, large-scale methods are desired to boost the efficiency and improve the practicality of solar steam generation. We developed a membrane-supported floating solar steam generation system based on graphene oxide and a multiscale plasmonic nanostructure; the latter is a micrometer-sized colloidosome that was assembled from hollow and porous Ag/Au nanocubes. By taking advantage of multiscale plasmonic coupling of the particles, an extremely high solar thermal conversion efficiency up to 92% at 10 kW·m^-2 （with a water evaporation rate reaching 12.96 kg·m^-2·h^-1） can be achieved. The TiO2 nanoparticle-modified floating system is also capable of high-efficiency dye degradation in organic-polluted water, rendering such a membrane system recyclable and scalable for practical and versatile solar-driven generation of clean water.
基金supported by the National Natural Science Foundation of China(NSFC grant no.21935004).
文摘Traditional flame-retardant plastics are technically difficult to chemically recycle.The development of newtypes of flame-retardant plastics that are intrinsically capable of being closed-loop recycled and are sufficiently robust and stable to satisfy their practical application is urgently needed.In this study,closed-loop recyclable flame-retardant plastics with high mechanical strength and excellent chemical resistance are fabricated by cross-linking amino-terminated polyimide(PI-NH_(2))and aldehyde-terminated cyclophosphazene(CP-CHO)with imine bonds.The resultant flame-retardant plastic,which is denoted as PI-CP,exhibits a tensile strength of∼115.6 MPa,Young’s modulus of∼2.5 GPa,and glass transition temperature of 316°C.In the PI-CP plastic,the imine bonds are isolated within hydrophobic microenvironments generated by the rigid and hydrophobic polyimide chains and the benzene ring of cyclophosphazenes.As a result,the PI-CP plastics are highly stable in highly acidic and basic aqueous solutions and other commonly used organic solvents.The PI-CP plastic shows outstanding flame retardancy with a limiting oxygen index value of 48.8%.More importantly,the PI-CP plastic can be depolymerized to generate the original PI-NH_(2)and CPCHO monomers in high yields(∼97%)and purity.The recovered monomers can be used to refabricate the original plastics,establishing highly efficient polymer-monomer-polymer circulation and a sustainable plastics economy.
基金sponsored by the National Natural Science Foundation of China(No.52008026)Natural Science Basic Research Program of Shaanxi(No.2021JQ-272)the Fundamental Research Funds for the Central Universities(No.300102219310,No.300102211303)。
文摘Concrete-filled rectangular steel tubular(CFRST)composite truss bridge is a new type of structure composed of a CFRST truss and concrete deck slab.This new type of bridge has the advantages of high structural force-transferring efficiency,rapid assembly construction speed and excellent total life cycle,which meets the construction concept of green,recyclable and sustainable development.Due to the broad application prospects,experiment on the flexural behavior of CFRST composite truss bridge in the negative moment region was reported by authors previously.This paper thus presents a finite element analysis(FEA)modelling verified by the reported test data to further investigate the detailed analytical behavior of this structure.The structural response and failure mechanism of CFRST composite truss beam in the negative moment region are studied.In addition,the important structural design parameters on the flexural performance of the CFRST composite truss beam are also investigated,including the height to span ratio,the brace-to-chord wall thickness ratio,the reinforcement ratio of steel reinforcements and prestressed tendons and the strength grade of concrete infill in chords.Finally,the reasonable structural design parameters range are proposed for the optimum design of the CFRST composite truss bridge.
基金financially supported by the National Natural Science Foundation of China(Nos.51573172,11405149 and 51401187)the Science and Technology Planning Project of Sichuan Province(No.SCXSDTR15001)Director’s Funds of China Academy of Engineering Physics(No.SJZ201506)
文摘A self-healing and recyclable carbon tube/epoxy adhesive was prepared by epoxy monomer with Diels-Alder （DA） bonds, diethylenetriamine and polyethyleneimine modified multi-wall carbon nanotubes （MWCNTs）. The self-healing and recyclable ability was attained by thermally reversible Diels-Alder reaction between furan and maleimide in the epoxy monomer. By controlling the molar ratio of furfuryl glycidyl ether and 4,4＇-methylenebis（N-phenylmaleimide）, the glass transition temperature and mechanical properties of MWCNTs/epoxy adhesives were varied. The self-healing properties of MWCNTs/epoxy polymers were evaluated by lap shear experiment and the results showed that the MWCNTs/epoxy adhesives exhibited enhanced mechanical properties and excellent self-healing ability under heat stimulus. The healing efficiency was related to the molecule mobility and the conversion of DA reaction between furan and maleimide. The MWCNTs/epoxy adhesives also displayed excellent recyclable ability by transforming into soluble polymer under heating. These materials offer a wide range of possibilities to produce materials with healing and recyclable ability and have the potential to bring great benefits to our daily lives by enhancing the safety, performance, and lifetime of products.
