By the random distribution of metals in a single phase,entropy engineering is applied to construct dense neighboring active centers with diverse electronic and geometric structures,realizing the continuous optimizatio...By the random distribution of metals in a single phase,entropy engineering is applied to construct dense neighboring active centers with diverse electronic and geometric structures,realizing the continuous optimization of multiple primary reactions for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).Many catalysts developed through entropy engineering have been built in nearly equimolar ratios to pursue high entropy,hindering the identification of the active sites and potentially diluting the concentration of real active sites while weakening their electronic interactions with reaction intermediates.Herein,this work proposes an entropy-engineering strategy in metal nanoparticle-embedded nitrogen carbon electrocatalysts,implemented by entropy-engineered Prussian blue analogs(PBA)as precursors to enhance the catalytic activity of primary Cu-Fe active sites.Through the introduction of the micro-strains driven by entropy engineering,density functional theory(DFT)calculations and geometric phase analysis(GPA)using Lorentz electron microscopy further elucidate the optimization of the adsorption/desorption of intermediates.Furthermore,the multi-dimensional morphology and the size diminishment of the nanocrystals serve to expand the electrochemical area,maximizing the catalytic activity for both ORR and OER.Notably,the Zn-air battery assembled with CuFeCoNiZn-NC operated for over 1300 h with negligible decay.This work presents a paradigm for the design of low-cost electrocatalysts with entropy engineering for multi-step reactions.展开更多
Transparent ZrO2-polyurethane nanocomposites with high refractive index were prepared by dispersing ZrO2 nanoparticles in a polyurethane matrix via ligand molecule engineering. TEM showed that the inorganic particles ...Transparent ZrO2-polyurethane nanocomposites with high refractive index were prepared by dispersing ZrO2 nanoparticles in a polyurethane matrix via ligand molecule engineering. TEM showed that the inorganic particles were well dispersed within the polymeric network with no significant macroscopic agglomeration. By controlling the phase separation it was possible to obtain transparent zirconia nanostructured coatings, characterized by improved mechanical and thermal properties. UV-Vis spectra indicated that the coatings still maintained transparency in the visible light. The refractive index of the UV-cured films depends linearly on the ZrO2 content and varies from 1.475 to 1.625 （20 wt%） at 633 nm. These coatings could find advanced applications in coatings of optical and electronic devices.展开更多
Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide.The curing ability o...Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide.The curing ability of the titanium-oxo-cluster was examined using a microdielectric analytical(DEA)curing monitor,Fourier transformed infrared spectroscopy(FTIR),and Soxhlet extraction experiments,and the properties of the resulted coatings were investigated with pendulum hardness tester,dynamic mechanical analysis(DMA),thermogravimetric analysis(TGA)and ultraviolet-visible spectrometer.The effect of titania-oxo-cluster in leading acrylic oligomers to form thermosetting acrylic coatings was confirmed.An increasing pendulum hardness and modulus of acrylic coatings with increasing titania content was observed, which resulted from the increment of crosslinking degree rather than of the titania content.The thermosetting acrylic/titania coatings also showed better thermal stability and higher UV-blocking properties than those coatings using organic curing agent.展开更多
Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and neg...Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and negative charges renders the zwitterion-based materials with electrostatically induced hydration properties, which enables a high resistance towards oily pollutants, nonspecific protein adsorption, bacterial adhesion and biofilm formation. This review starts from the working mechanism of zwitterions and covers the fabrication strategies of zwitterion-based functional coatings, namely the zwitterion-bearing binder route, the zwitterion-bearing additive route and the post-generation of coatings containing zwitterionic precursors. The applications of zwitterion-based functional coatings are discussed, including medical implants, marine antifouling and oil-resistant coatings, with focus on the relevant mechanisms of the zwitterion-containing coatings for a specific performance. Finally, some comments and perspectives on the current situation and future development of zwitterion-based functional coatings are given.展开更多
Despite significant progress in the structure and properties of porous absorbing materials,major challenges remain due to complex preparation technology,high production costs,and poor corrosion resistance.In this stud...Despite significant progress in the structure and properties of porous absorbing materials,major challenges remain due to complex preparation technology,high production costs,and poor corrosion resistance.In this study,nanowires were used as the substrate,liquid nitrogen controls ice crystal growth orientation,and ammonia gas facilitates the generation of magnetic substances.The resulting pure magnetic porous foam(PMF)material exhibits enhanced performance in absorbing electromagnetic waves(EMWs)and improved corrosion resistance.The PMF's microstructure was analyzed for its dielectric and magnetic loss characteristics.The PMF combines a porous framework,nanoscale architecture,and exclusive magnetic components to create a lightweight foam absorbent material with enhanced magnetic dissipation capabilities.Among them,the Fe_(4)N PMF demonstrates an impressive minimum reflection loss(RLmin)value of−66.8 dB at a thickness of 1.09 mm,exhibits an effective absorption bandwidth of 4.00 GHz,and shows exceptional corrosion resistance with a self-corrosion potential of−0.65 V.Moreover,the effectiveness of the Fe_(4)N PMF in absorbing intelligent EMWs has been validated through radar cross-section(RCS)simulations.In summary,this study has developed electromagnetic wave-absorbing materials with slim profiles,lightweight properties,strong absorption capabilities,and excellent corrosion resistance.These characteristics make them highly promising for microwave absorption applications.展开更多
A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size an...A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamic mechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviously improve the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhance the store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHC content increased. TEM shows that the prepared polymers were actually organic-inorganic nanocomposites, and these films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organic silicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperature than organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.展开更多
Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surfa...Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.展开更多
The effect of radio-frequency （RF） or low-frequency （LF） bias voltage on the for- mation of amorphous hydrogenated carbon （a-C：H） films was studied on silicon substrates with a low methane （CH4） concentration...The effect of radio-frequency （RF） or low-frequency （LF） bias voltage on the for- mation of amorphous hydrogenated carbon （a-C：H） films was studied on silicon substrates with a low methane （CH4） concentration （2-10 vol.%） in CH4＋Ar mixtures. The bias substrate was applied either by RF （13.56 MHz） or by LF （150 kHz） power supply. The highest hardness values （~18-22 GPa） with lower hydrogen content in the fihns （~20 at.%） deposited at 10 vol.% CH4, was achieved by using the RF bias, However, the films deposited using the LF bias, under similar RF plasma generation power and CH4 concentration （50 W and 10 vol.%, respectively）, displayed lower hardness （~6-12 GPa） with high hydrogen content （~40 at.%）. The structures analyzed by Fourier Transform Infrared （FTIR） and Raman scattering measurements provide an indication of trans-polyacetylene structure formation. However, its excessive formation in the films deposited by the LF bias method is consistent with its higher bonded hydrogen concentration and low level of hardness, as compared to the film prepared by the RF bias method. It was found that the effect of RF bias on the film structure and properties is stronger than the effect of the low-frequency （LF） bias under identical radio-frequency （RF） powered electrode and identical PECVD （plasma enhanced chemical vapor deposition） system configuration.展开更多
A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS...A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS. contact angle system,protein adsorption and platelets adhesion measurements,respectively.It was found that as the molecular weight of PDMS increased,the surface of copolymers had increasing phase separation,while the increase in the molecular weight of PEG decreased the phase separation extents of the copolymer surface.XPS and contact angle measurements showed that the greater the phase separation extent was,the lower both the surface enrichment of PDMS and the surface free energy of the copolymer film were.The protein adsorption experiments indicated that the best phase separation did not exhibit the best biocompatibility.展开更多
Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,...Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.展开更多
The simultaneous enhancement of magnetic and dielectric properties in nanomaterials is becoming increasingly important for achieving exceptional microwave absorption performance.However,the engineering strategies for ...The simultaneous enhancement of magnetic and dielectric properties in nanomaterials is becoming increasingly important for achieving exceptional microwave absorption performance.However,the engineering strategies for modulating electromagnetic responses remain challenging,and the underlying magnetic-dielectric loss mechanisms are not yet fully understood.In this study,we constructed novel dual-coupling networks through the tightly packed Fe_(3)O_(4)@C spindles,which exhibit both dielectric and magnetic dissipation effects.During the spray-drying process,vigorous self-assembly facilitated the formation of hierarchical microspheres composed of nanoscale core-shell ferromagnetic units.Numerous heterogeneous interfaces and abundant magnetic domains were produced in these microspheres.The integrated dielectric/magnetic coupling networks,formed by discontinuous carbon layers and closely arranged Fe_(3)O_(4)spindles,contribute to strong absorption through intense interfacial polarization and magnetic interactions.The mechanisms behind both magnetic and dielectric losses are elucidated through Lorentz electron holography and micromagnetic simulations.Consequently,the hierarchical microspheres demonstrate excellent low-frequency absorption performance,achieving an effective absorption bandwidth of 3.52 GHz,covering the entire C-band from 4 to 8 GHz.This study reveals that dual-coupling networks engineering is an effective strategy for synergistically enhancing electromagnetic responses and improving the absorption performance of magnetic nanomaterials.展开更多
Efficient,temperature-insensitive electromagnetic attenuation materials are critical for high microwave absorption at high temperatures.This study presents SiC/TiC/SiTiOC hybrid nanofiber mats constructed using an in-...Efficient,temperature-insensitive electromagnetic attenuation materials are critical for high microwave absorption at high temperatures.This study presents SiC/TiC/SiTiOC hybrid nanofiber mats constructed using an in-situ synthesis method;these mats incorporate SiC/TiC as the microwave loss unit and SiTiOC as the antioxidant unit,offering an innovative approach to high-temperature microwave absorption.The introduction of high-conductivity TiC not only optimizes the dielectric constant and impedance matching of the material but also enhances its thermal cycling stability.This design ensures steady electromagnetic attenuation,enabling the hybrid nanofiber mats to maintain robust absorption performance in the X-band,even at high temperatures.At 873 K,the material demonstrates an effective absorption bandwidth of 3.6 GHz and a minimum reflection loss of−45.55 dB.Compared to single-system absorbers,such as SiC/C nanofiber materials,with a single system,the multicomponent SiC/TiC/SiTiOC hybrid nanofiber mats deliver reliable absorption performance in the temperature range of 293-873 K.This study confirms that highly conductive titanium-based ceramic materials used for dielectric property regulation effectively address the challenges of poor temperature stability and limited reusability in high-temperature carbon-ceramic absorbing materials,providing valuable insights and guidance for designing efficient microwave absorbers that can operate across a wide temperature range.展开更多
With the progress of electronic communication technology,the intensity of electromagnetic radiation is getting strength,and the traditional absorbing materials can no longer meet the needs of various current environme...With the progress of electronic communication technology,the intensity of electromagnetic radiation is getting strength,and the traditional absorbing materials can no longer meet the needs of various current environments.Dielectric nanomaterials have received much attention in energy conversion,electromagnetic shielding and absorption due to their nanosize effects and structural tunable properties.However,the mismatch impedance and the single loss mechanism severely limit its application in the field of microwave absorption.In this paper,we modified the doped ZnCo_(2)O_(4) with the guidance of density functional theory(DFT)simulation,effectively regulate the dielectric parameters and adjust the microwave absorption characteristics,which stems from the transformation of electron energy between doped ions and some defects.Meanwhile,we further experimentally observe significant magnetic components at the doped ZnCo_(2)O_(4),resulting in improved magnetic properties and producing a large number of dipoles.Due to the best impedance match and enhanced polarization loss,the minimum reflection loss is−37 dB,and the effective absorption bandwidth(EAB)is 7.21 GHz.This provides ideas for the design of cobalt acid-based materials as efficient microwave absorbers.展开更多
基金supported by the National Natural Science Foundation of China(52071083,52231007,12327804,52471224)Zhuhai Fudan Innovation Institute,and the Science and Technology Commission of Shanghai Municipality(23ZR1405000).
文摘By the random distribution of metals in a single phase,entropy engineering is applied to construct dense neighboring active centers with diverse electronic and geometric structures,realizing the continuous optimization of multiple primary reactions for oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).Many catalysts developed through entropy engineering have been built in nearly equimolar ratios to pursue high entropy,hindering the identification of the active sites and potentially diluting the concentration of real active sites while weakening their electronic interactions with reaction intermediates.Herein,this work proposes an entropy-engineering strategy in metal nanoparticle-embedded nitrogen carbon electrocatalysts,implemented by entropy-engineered Prussian blue analogs(PBA)as precursors to enhance the catalytic activity of primary Cu-Fe active sites.Through the introduction of the micro-strains driven by entropy engineering,density functional theory(DFT)calculations and geometric phase analysis(GPA)using Lorentz electron microscopy further elucidate the optimization of the adsorption/desorption of intermediates.Furthermore,the multi-dimensional morphology and the size diminishment of the nanocrystals serve to expand the electrochemical area,maximizing the catalytic activity for both ORR and OER.Notably,the Zn-air battery assembled with CuFeCoNiZn-NC operated for over 1300 h with negligible decay.This work presents a paradigm for the design of low-cost electrocatalysts with entropy engineering for multi-step reactions.
基金supported by the Shanghai Leading Academic Discipline Project(No.B 113)
文摘Transparent ZrO2-polyurethane nanocomposites with high refractive index were prepared by dispersing ZrO2 nanoparticles in a polyurethane matrix via ligand molecule engineering. TEM showed that the inorganic particles were well dispersed within the polymeric network with no significant macroscopic agglomeration. By controlling the phase separation it was possible to obtain transparent zirconia nanostructured coatings, characterized by improved mechanical and thermal properties. UV-Vis spectra indicated that the coatings still maintained transparency in the visible light. The refractive index of the UV-cured films depends linearly on the ZrO2 content and varies from 1.475 to 1.625 （20 wt%） at 633 nm. These coatings could find advanced applications in coatings of optical and electronic devices.
基金supported by the National Natural Science Foundation of China(No.20774023)Shanghai Leading Academic Discipline Project(No.B113).
文摘Thermosetting acrylic coatings were prepared by using carboxyl acid group-containing acrylic oligomer and curing with titanium-oxo-clusters which were first pre-hydrolyzed from titanium n-butoxide.The curing ability of the titanium-oxo-cluster was examined using a microdielectric analytical(DEA)curing monitor,Fourier transformed infrared spectroscopy(FTIR),and Soxhlet extraction experiments,and the properties of the resulted coatings were investigated with pendulum hardness tester,dynamic mechanical analysis(DMA),thermogravimetric analysis(TGA)and ultraviolet-visible spectrometer.The effect of titania-oxo-cluster in leading acrylic oligomers to form thermosetting acrylic coatings was confirmed.An increasing pendulum hardness and modulus of acrylic coatings with increasing titania content was observed, which resulted from the increment of crosslinking degree rather than of the titania content.The thermosetting acrylic/titania coatings also showed better thermal stability and higher UV-blocking properties than those coatings using organic curing agent.
基金Sponsored by the National Key Research and Development Program of China(Grant No.2020YFE0100300)the National Natural Science Foundation of China(Grant No.51973036)。
文摘Zwitterion-based materials by virtue of their special physical and chemical characteristics have attracted researchers to utilize them for fabricating functional coatings. The simultaneous presence of positive and negative charges renders the zwitterion-based materials with electrostatically induced hydration properties, which enables a high resistance towards oily pollutants, nonspecific protein adsorption, bacterial adhesion and biofilm formation. This review starts from the working mechanism of zwitterions and covers the fabrication strategies of zwitterion-based functional coatings, namely the zwitterion-bearing binder route, the zwitterion-bearing additive route and the post-generation of coatings containing zwitterionic precursors. The applications of zwitterion-based functional coatings are discussed, including medical implants, marine antifouling and oil-resistant coatings, with focus on the relevant mechanisms of the zwitterion-containing coatings for a specific performance. Finally, some comments and perspectives on the current situation and future development of zwitterion-based functional coatings are given.
基金financially supported by the National Natural Science Foundation of China(No.52471212)the National Key Research and Development Program(No.2022YFE0109800).
文摘Despite significant progress in the structure and properties of porous absorbing materials,major challenges remain due to complex preparation technology,high production costs,and poor corrosion resistance.In this study,nanowires were used as the substrate,liquid nitrogen controls ice crystal growth orientation,and ammonia gas facilitates the generation of magnetic substances.The resulting pure magnetic porous foam(PMF)material exhibits enhanced performance in absorbing electromagnetic waves(EMWs)and improved corrosion resistance.The PMF's microstructure was analyzed for its dielectric and magnetic loss characteristics.The PMF combines a porous framework,nanoscale architecture,and exclusive magnetic components to create a lightweight foam absorbent material with enhanced magnetic dissipation capabilities.Among them,the Fe_(4)N PMF demonstrates an impressive minimum reflection loss(RLmin)value of−66.8 dB at a thickness of 1.09 mm,exhibits an effective absorption bandwidth of 4.00 GHz,and shows exceptional corrosion resistance with a self-corrosion potential of−0.65 V.Moreover,the effectiveness of the Fe_(4)N PMF in absorbing intelligent EMWs has been validated through radar cross-section(RCS)simulations.In summary,this study has developed electromagnetic wave-absorbing materials with slim profiles,lightweight properties,strong absorption capabilities,and excellent corrosion resistance.These characteristics make them highly promising for microwave absorption applications.
基金Supported by the National "863" Project (No. 2001 AA 320206)and Shanghai Nano Special Foundation(No. 0120nm034).
文摘A poly (St-co-BA) latex was successfully synthesized by using an organic-inorganic hybrid compound (OIHC), an aliphatic carboxylate sodium/nano-silica composite, as the emulsifier, and investigated by particle size analyzer, transmission electron microscope (TEM), optical contact angle measurement (OCA) and dynamic mechanical analyzer (DMA). It was found that the protective agent, sodium polyacrylate (PA),could obviously improve the polymerization stability and the functional monomer, glycidyl methacrylate (GMA), could enhance the store stability of the latex. The particle size of poly(St-co-BA) latex decreased and then leveled off as OIHC content increased. TEM shows that the prepared polymers were actually organic-inorganic nanocomposites, and these films have better waterproof property than those prepared by traditional poly(St-co-BA) latex or organic silicone modified poly(St-co-BA) latex. The nanocomposite polymer has much higher glass transition temperature than organic silicone modified poly(St-co-BA) polymer containing the same organic silicone content.
基金This research was financially supported by the Key Project of China Educational Ministry (No. 103064)the Doctoral Foundation of University (No. 20020246031)
文摘Poly（St-co-BuA）/silica nanocomposite latexes were synthesized via conventional emulsion polymerization in the presence of 3-（trimethoxysilyl）propyl methacrylate modified colloidal nano-silica. The effects of surface property, particle size and content of colloidal nano-silica as well as the concentrations of monomer and surfactant on the morphology of nanocomposite latex particles were investigated by transmission electron microscope （TEM） and scanning electron microscope （SEM） in detail. Various interesting morphologies such as grape-like, Chinese gooseberry-like, pomegranate-like and normal core-shell structures were observed. Droplet nucleation mechanism competing with micelle nucleation mechanism was proposed to explain the morphological evolution of the nanocomposite particles.
基金supported by a grant from the Israel Atomic Energy Commission for international collaborations
文摘The effect of radio-frequency （RF） or low-frequency （LF） bias voltage on the for- mation of amorphous hydrogenated carbon （a-C：H） films was studied on silicon substrates with a low methane （CH4） concentration （2-10 vol.%） in CH4＋Ar mixtures. The bias substrate was applied either by RF （13.56 MHz） or by LF （150 kHz） power supply. The highest hardness values （~18-22 GPa） with lower hydrogen content in the fihns （~20 at.%） deposited at 10 vol.% CH4, was achieved by using the RF bias, However, the films deposited using the LF bias, under similar RF plasma generation power and CH4 concentration （50 W and 10 vol.%, respectively）, displayed lower hardness （~6-12 GPa） with high hydrogen content （~40 at.%）. The structures analyzed by Fourier Transform Infrared （FTIR） and Raman scattering measurements provide an indication of trans-polyacetylene structure formation. However, its excessive formation in the films deposited by the LF bias method is consistent with its higher bonded hydrogen concentration and low level of hardness, as compared to the film prepared by the RF bias method. It was found that the effect of RF bias on the film structure and properties is stronger than the effect of the low-frequency （LF） bias under identical radio-frequency （RF） powered electrode and identical PECVD （plasma enhanced chemical vapor deposition） system configuration.
基金supported by the Shanghai Special Nano Foundation and Shanghai Sci.& Tech.Foundation.
文摘A series of poly(dimethylsiloxane)(PDMS)-4,4′-diphenylmethanediisocyanate(MDI)-poly(ethylene glycol)(PEG) multiblock copolymers were synthesized by employing two-step growth polymerization and investigated by AFM,XPS. contact angle system,protein adsorption and platelets adhesion measurements,respectively.It was found that as the molecular weight of PDMS increased,the surface of copolymers had increasing phase separation,while the increase in the molecular weight of PEG decreased the phase separation extents of the copolymer surface.XPS and contact angle measurements showed that the greater the phase separation extent was,the lower both the surface enrichment of PDMS and the surface free energy of the copolymer film were.The protein adsorption experiments indicated that the best phase separation did not exhibit the best biocompatibility.
基金Project supported by the National Natural Science Foundation of China (Grant No.12104291)。
文摘Through equilibrium and non-equilibrium molecular dynamics simulations,we have demonstrated the inhibitory effect of composition graded interface on thermal transport behavior in lateral heterostructures.Specifically,we investigated the influence of composition gradient length and heterogeneous particles at the silicene/germanene(SIL/GER)heterostructure interface on heat conduction.Our results indicate that composition graded interface at the interface diminishes the thermal conductivity of the heterostructure,with a further reduction observed as the length increases,while the effect of the heterogeneous particles can be considered negligible.To unveil the influence of composition graded interface on thermal transport,we conducted phonon analysis and identified the presence of phonon localization within the interface composition graded region.Through these analyses,we have determined that the decrease in thermal conductivity is correlated with phonon localization within the heterostructure,where a stronger degree of phonon localization signifies poorer thermal conductivity in the material.Our research findings not only contribute to understanding the impact of interface gradient-induced phonon localization on thermal transport but also offer insights into the modulation of thermal conductivity in heterostructures.
基金National Natural Science Foundation of China,Grant/Award Numbers:52231007,12327804,T2321003,22088101National Key Research Program of China,Grant/Award Number:2021YFA1200600。
文摘The simultaneous enhancement of magnetic and dielectric properties in nanomaterials is becoming increasingly important for achieving exceptional microwave absorption performance.However,the engineering strategies for modulating electromagnetic responses remain challenging,and the underlying magnetic-dielectric loss mechanisms are not yet fully understood.In this study,we constructed novel dual-coupling networks through the tightly packed Fe_(3)O_(4)@C spindles,which exhibit both dielectric and magnetic dissipation effects.During the spray-drying process,vigorous self-assembly facilitated the formation of hierarchical microspheres composed of nanoscale core-shell ferromagnetic units.Numerous heterogeneous interfaces and abundant magnetic domains were produced in these microspheres.The integrated dielectric/magnetic coupling networks,formed by discontinuous carbon layers and closely arranged Fe_(3)O_(4)spindles,contribute to strong absorption through intense interfacial polarization and magnetic interactions.The mechanisms behind both magnetic and dielectric losses are elucidated through Lorentz electron holography and micromagnetic simulations.Consequently,the hierarchical microspheres demonstrate excellent low-frequency absorption performance,achieving an effective absorption bandwidth of 3.52 GHz,covering the entire C-band from 4 to 8 GHz.This study reveals that dual-coupling networks engineering is an effective strategy for synergistically enhancing electromagnetic responses and improving the absorption performance of magnetic nanomaterials.
基金supported by the National Natural Science Foundation of China(Grant Nos.52303352,52231007,12327804,T2321003,22088101)the National Key Research Program of China(Grant No.2021YFA1200600).
文摘Efficient,temperature-insensitive electromagnetic attenuation materials are critical for high microwave absorption at high temperatures.This study presents SiC/TiC/SiTiOC hybrid nanofiber mats constructed using an in-situ synthesis method;these mats incorporate SiC/TiC as the microwave loss unit and SiTiOC as the antioxidant unit,offering an innovative approach to high-temperature microwave absorption.The introduction of high-conductivity TiC not only optimizes the dielectric constant and impedance matching of the material but also enhances its thermal cycling stability.This design ensures steady electromagnetic attenuation,enabling the hybrid nanofiber mats to maintain robust absorption performance in the X-band,even at high temperatures.At 873 K,the material demonstrates an effective absorption bandwidth of 3.6 GHz and a minimum reflection loss of−45.55 dB.Compared to single-system absorbers,such as SiC/C nanofiber materials,with a single system,the multicomponent SiC/TiC/SiTiOC hybrid nanofiber mats deliver reliable absorption performance in the temperature range of 293-873 K.This study confirms that highly conductive titanium-based ceramic materials used for dielectric property regulation effectively address the challenges of poor temperature stability and limited reusability in high-temperature carbon-ceramic absorbing materials,providing valuable insights and guidance for designing efficient microwave absorbers that can operate across a wide temperature range.
基金supported by the National Natural Science Foundation of China(Nos.52231007,12327804,T2321003,22088101,22405050,12074241,52130204,and 11929401)the National Key Research and Development Program of China(Nos.2024YFA1208902,2024YFA1408001,and 2021YFA1200600)+4 种基金the Science and Technology Commission of Shanghai Municipality(No.24ZR1406400)Aeronautical Science Foundation of China(Nos.202400180P9001 and 2024M0730P9001)Key Laboratory of High Temperature Electromagnetic Materials and Structure of MOE(No.KB202401)Fund of Science and Technology on Surface Physics and Chemistry Laboratory(No.JCKYS2023120201)the Science and Technology Commission of Shanghai Municipality(Nos.19010500500,20501130600,21JC1402600,and 22YF1413300).
文摘With the progress of electronic communication technology,the intensity of electromagnetic radiation is getting strength,and the traditional absorbing materials can no longer meet the needs of various current environments.Dielectric nanomaterials have received much attention in energy conversion,electromagnetic shielding and absorption due to their nanosize effects and structural tunable properties.However,the mismatch impedance and the single loss mechanism severely limit its application in the field of microwave absorption.In this paper,we modified the doped ZnCo_(2)O_(4) with the guidance of density functional theory(DFT)simulation,effectively regulate the dielectric parameters and adjust the microwave absorption characteristics,which stems from the transformation of electron energy between doped ions and some defects.Meanwhile,we further experimentally observe significant magnetic components at the doped ZnCo_(2)O_(4),resulting in improved magnetic properties and producing a large number of dipoles.Due to the best impedance match and enhanced polarization loss,the minimum reflection loss is−37 dB,and the effective absorption bandwidth(EAB)is 7.21 GHz.This provides ideas for the design of cobalt acid-based materials as efficient microwave absorbers.
