Helicene-type compounds are renowned for their unique chiral properties,however,obtaining their enantiomers usually requires laborious and costly chiral separations.Moreover,their chiroptical activity is typically lim...Helicene-type compounds are renowned for their unique chiral properties,however,obtaining their enantiomers usually requires laborious and costly chiral separations.Moreover,their chiroptical activity is typically limited to the ultraviolet spectral range,which restricts their broader applicability.To overcome these limitations,a novel and efficient strategy for synthesizing optically active compounds through the incorporation of an optically pure binaphthol(BINOL)group onto the periphery of β-isoindigo based aza dipyrrometheneboron difluoride(aza-BODIPY)analogues(BIABs)was presented.The resulting(R)/(S)-BINOL-BIABs demonstrate exceptional photostability,deep-red emission,strong Cotton effect(Δε)and high absorbance dissymmetry factor(g_(abs)).Moreover,tunable circularly polarized luminescence(CPL)with high brightness in the deep-red region was achieved.This strategy offers straightforward procedures for synthesizing optically active compounds.展开更多
The small molecular second near-infrared(NIR-Ⅱ, 1000–1700 nm) dye-based nanotheranostics can concurrently combine deep-tissue photodiagnosis with in situ phototherapy, which occupies a vital position in the early de...The small molecular second near-infrared(NIR-Ⅱ, 1000–1700 nm) dye-based nanotheranostics can concurrently combine deep-tissue photodiagnosis with in situ phototherapy, which occupies a vital position in the early detection and precise treatment of tumors. However, the development of small molecular NIR-Ⅱ dyes is still challenging due to the limited electron acceptors and cumbersome synthetic routes.Herein, we report a novel molecular electron acceptor, boron difluoride formazanate(BDF). Based on BDF, a new small molecular NIR-Ⅱ dye BDF1005 is designed and synthesized with strong NIR-I absorption at 768 nm and bright NIR-Ⅱ peak emission at 1034 nm. In vitro and in vivo experiments demonstrate that BDF1005-based nanotheranostics can be applied for NIR-Ⅱ fluorescence imaging-guided photothermal therapy of 4T1 tumor-bearing mice. Under 808 nm laser irradiation, tumor growth can be effectively inhibited. This work opens up a new road for the exploitation of NIR-Ⅱ small molecular dyes for cancer phototheranostics.展开更多
Herein we report a new general method for one-step synthesis of four kinds of fluoroiodane(Ⅲ)reagents by treating the corresponding aryl iodides with silver difluoride(AgF_(2)).This is the first method applicable for...Herein we report a new general method for one-step synthesis of four kinds of fluoroiodane(Ⅲ)reagents by treating the corresponding aryl iodides with silver difluoride(AgF_(2)).This is the first method applicable for the synthesis of all four fluoroiodane(Ⅲ)reagents including p-iodotoluene difluoride(1),fluoro-benziodoxole(2),fluoro-benziodoxolone(3),and fluoro-N-acetylbenziodazole(4).AgF_(2)was firstly employed in the direct oxidative fluorination of iodobenzene and thus has shown its outstanding oxidation and fluorine-transfer ability.The use of AgF_(2)has improved the synthesis of fluoroiodane(Ⅲ)reagents by shortening the reaction steps,avoiding the use of hazardous reagents,and simplifying the experimental operations.It was worth noting that we have developed the first one-step direct synthetic method for 3,while 3 can only be synthesized through Cl→F ligand exchange reaction previously.展开更多
Developing safe and high-performance solid polymer electrolytes(SPEs) remains a critical challenge for all-solid-state batteries.Among various polymer materials,poly(ethylene oxide)(PEO) is most widely studied,while p...Developing safe and high-performance solid polymer electrolytes(SPEs) remains a critical challenge for all-solid-state batteries.Among various polymer materials,poly(ethylene oxide)(PEO) is most widely studied,while poly(vinylidene fluoride)(PVDF)has also attracted great interest recently.However,the intrinsic disadvantages of single polymers make them hardly meet the demands for practical applications.Physical blending of different types of SPEs is a simple and straightforward strategy to optimize their performance.Unfortunately,the direct blending of PEO and PVDF(or PVDF derivatives) usually leads to macrophase separation and fails to couple together.Herein,we designed and synthesized PEO-based block copolymers as compatibilizers to prevent macroscopic phase separation in PVDF/PEO blends.By tuning the interfacial compatibility,continuous nanostructures with high optical transparency are constructed through the microphase segregation.The obtained SPEs combine the merits of high mechanical modulus(380 MPa),high ionic conductivity(2.0 × 10^(-4)S cm^(-1),30 ℃),large transference number(0.60),and electrochemical stability(4.5 V).This simple and efficient chemical modification approach sheds light on alternative solutions for designing high-performance SPEs.展开更多
Bulk-type all-solid-state batteries(ASSBs)using sulfide solid electrolyte are considered as a promising alternative to commercial lithium-ion batteries owing to their high energy density and safety.However,cell energy...Bulk-type all-solid-state batteries(ASSBs)using sulfide solid electrolyte are considered as a promising alternative to commercial lithium-ion batteries owing to their high energy density and safety.However,cell energy density is often comparatively low due to use of a thick solid electrolyte separator and a lithium alloy as anode.For achieving high-performance ASSBs,creating a thin free-standing electrolyte with high-conductivity and good cycling stability against lithium anode is essential.In this work,we present Li_(6)PS_(5)Cl/poly(vinylidene difluoride)(LPSCl/PVDF)composite electrolytes prepared by a slurry method.The influence of the PVDF content on the microstructure,morphology,ionic conductivity and activation energy of the LPSCl/PVDF electrolytes is systematically investigated.Free-standing LPSCl/PVDF membranes with a thickness of 100-120 mm and a high ionic conductivity of about 1·10^(-3) S cm^(-1) at 25℃ are obtained.After adding PVDF to the LPSCl electrolyte,the cycling stability of the LPSCl electrolyte against lithium metal improves significantly.Therefore,LPSCl/PVDF composite electrolytes are promising candidates to be used in ASSBs.展开更多
The dynamic process of the ionic valence changing from Eu^(2+) to Eu^(3+) in EuF_2 at high temperature has been investigated by ESCA, high,temperature X-ray diffraction, high temperature spectrum, high temperature mag...The dynamic process of the ionic valence changing from Eu^(2+) to Eu^(3+) in EuF_2 at high temperature has been investigated by ESCA, high,temperature X-ray diffraction, high temperature spectrum, high temperature magnetic Isusceptibility and Mssbauer spectrum. It has been shown that the formed Eu^(3+) exists in different compounds when EuF_2 is heated to high temperature in different atmospheres. In air, Eu^(3+) exists in the form of hexagonal EuOF, in nitrogen, in the form of orthogonal EuF_3 and non-hexagon EuOF. This is because decomposition or disproportionation of EuF_2 is different with different atmospheres. The magnetic susceptibility measurement showed quantitatively that the change rate from Eu^(2+) to Eu^(3+) is about 95% in air, and about 75% in nitrogen when it is heated to 900℃. A small amount of Eu^(2+) coexists with Eu^(3+) in the final product.展开更多
Exploring lanthanide doped materials and their high-pressure optical properties is important from the perspective of designing pressure sensors, piezoelectric materials, scintillators, and optoelectronic devices, just...Exploring lanthanide doped materials and their high-pressure optical properties is important from the perspective of designing pressure sensors, piezoelectric materials, scintillators, and optoelectronic devices, just to mention a few. Understanding the high-pressure optical properties of polymeric fibrous mats provides significant advantages in terms of flexibility, tunability, facile processability, and malleability. In this work, we have developed flexible polyvinylidene difluoride(PVDF) fibrous mats doped with an Eu^(3+) source of Eu(NO_(3))_(3)·5H_(2)O(EN-PF) or Eu_(2)(SO_(4))_(3)(ES-PF) by a Forcespinning■ method. Microstructural analysis of these two systems indicates that Eu(NO_(3))_(3)·5H_(2)O and Eu_(2)(SO_(4))_(3) are homogeneously distributed and dispersed into the PVDF matrix. Fiber formation promotes a β-phase PVDF. Eu^(3+) doping increases the β-phase. Its fraction is larger for the ES-PF mats. To understand their high-pressure optical properties, their photoluminescence spectra have been taken at various pressures up to 58 GPa in a diamond anvil cell. High-pressure luminescence illustrates a clear change in asymmetry ratio, peak intensity, peak breadth, color coordinate, and color temperature of Eu^(3+) ions from both EN-PF and ES-PF with a different extent of changes. Specifically, Eu^(3+) ions in the ES-PF mats switch from asymmetric to symmetric environment as pressure increases. Those in the EN-PF mats present symmetric environment for all tested pressures. Both of the Eu^(3+) doped PVDF systems present irreversible changes. Therefore,the EN-PF fibrous mats present an opportunity to make pressure induced red-orange-yellow tunable phosphors for multifunctional applications.展开更多
Fluoride processing of natural ilmenite with the use of ammonium hydrogen difluoride (NH4HF2) as an effective fluorinating agent is suggested. Chemistry, composition, structure, thermal and hydrolytic properties of fl...Fluoride processing of natural ilmenite with the use of ammonium hydrogen difluoride (NH4HF2) as an effective fluorinating agent is suggested. Chemistry, composition, structure, thermal and hydrolytic properties of fluorination products were investigated. Ammonium fluoro- and oxofluorotitanates are suitable for preparing of titanium dioxide as pigmentary product or as doped by nitrogen and fluorine.展开更多
An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of A...An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.展开更多
To enhance the piezoelectric performance of piezoelectric polymer thin films in general,hybrid polyvinylidene difluoride(PVDF)and nanosized barium titanate(BaTiO_(3))piezoelectric films were prepared and their piezoel...To enhance the piezoelectric performance of piezoelectric polymer thin films in general,hybrid polyvinylidene difluoride(PVDF)and nanosized barium titanate(BaTiO_(3))piezoelectric films were prepared and their piezoelectric performance examined.The hybrid nanofibers were fabricated via electrospinning at an external voltage of 15 kV.The nonwoven fabrics were collected using a roller collection device,and their morphological structures were analyzed via scanning electron microscopy.The crystal structures of these piezoelectric films were characterized via micro-Raman spectroscopy.β-phase of the composite nanofiber membrane almost increased to twice owing to the addition of BaTiO_(3)nanoparticles.Compared with pure,electrospun PVDF piezoelectric film,the piezoelectric characteristics of the hybrid piezoelectric films were considerably enhanced because of the additional BaTiO_(3)nanoparticles.The maximum instantaneous open-circuit voltage of the hybrid PVDF-BaTiO_(3)nanofibers film can be high up to 80 V.The high-performance hybrid piezoelectric films exhibited notable prospects for applications in wearable electronic textiles.展开更多
Owing to its unique ability to capture volumetric tomographic information with a single light flash,optoacoustic(OA)tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound ti...Owing to its unique ability to capture volumetric tomographic information with a single light flash,optoacoustic(OA)tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound time-of-flight.The method's scalability and the achievable spatial resolution are yet limited by the narrow bandwidth of piezo-composite arrays currently employed for OA signal detection.Here we report on the first implementation of high-density spherical array technology based on flexible polyvinylidene difluoride films featuring ultrawideband(0.3-40 MHz)sub mm^(2)area elements,thus enabling real-time multi-scale volumetric imaging with 22-35μm spatial resolution,superior image fidelity and over an order of magnitude signal-to-noise enhancement compared to piezo-composite equivalents.We further demonstrate five-dimensional(spectroscopic,time-resolved,volumetric)imaging capabilities by visualizing fast stimulus-evoked cerebral oxygenation changes in mice and performing real-time functional angiography of deep human micro-vasculature.The new technology thus leverages the true potential of OA for quantitative high-resolution visualization of rapid bio-dynamics across scales.展开更多
Polyvinylidene difluoride(PVDF)derivatives in metal/PVDF/metal(MPM)sandwich structures have been studied extensively since 1969.Cousin copolymers of the same family have been discovered with fascinating piezoelectric,...Polyvinylidene difluoride(PVDF)derivatives in metal/PVDF/metal(MPM)sandwich structures have been studied extensively since 1969.Cousin copolymers of the same family have been discovered with fascinating piezoelectric,pyroelectric,electrocaloric,and ferroelectric properties.Solution processing,flexibility,lightweight,and thermal stability make this class of materials complementary to inorganics.Thus,PVDF based polymers potentially compete with inorganic materials for a broad range of technologies such as energy generators,loudspeakers,coolers,and memories.However,the stable non-electroactiveα-phase and hydrophobic nature of PVDF are the main barriers for developoing high performing and robust MPM devices in electronic applications.In this review,we present an up-to-date overview on different methods to induce the electroactiveβ-phase and improve the adhesion strength with metals to ensure robust and durable MPM devices.We go through advantages and disadvantages of several methods and pinpoint future opportunities in this research area.A special attention is paid to wearable piezoelectric nanogenerators for energy harvesting from human body motion,where flexible PVDF derivatives are compared with rigid piezoelectric ceramics.While the piezoelectric coefficient of PVDF(d_(33)~24–34 pm/V)is one order lower than ceramic materials,novel co-polymers of PVDF display d_(33)>1000 pm/V upon bias.This shows promise to bring piezoelectrics to flexible and large-area applications such as smart textiles.We also discussed challenges to improve wearability,such as light weight,breathability,and flexibility.展开更多
A novel and facile preparation of l,l-difluoroallyl substituted five-membered lactones or pyrrolidines in mod- erate yields through direct double electrophilic fluorination of 4,5-allenoic acids or tosylamides with Se...A novel and facile preparation of l,l-difluoroallyl substituted five-membered lactones or pyrrolidines in mod- erate yields through direct double electrophilic fluorination of 4,5-allenoic acids or tosylamides with SelectfluorTM F-TEAD-BF4 is described.展开更多
Nonstoichiometric series SmF_x (2.0≤x≤3.0) have been synthesized by reduction of samarium trifluoride with hydrogen for several times, and the stoichiometric samarium difluoride has been obtained. The structure of n...Nonstoichiometric series SmF_x (2.0≤x≤3.0) have been synthesized by reduction of samarium trifluoride with hydrogen for several times, and the stoichiometric samarium difluoride has been obtained. The structure of nonstoichiometric samarium fluoride series and the valency of samarium ion are briefly discussed. The valent change process of samarium ion at high temperatures in different atmospheres is investigated.展开更多
文摘Helicene-type compounds are renowned for their unique chiral properties,however,obtaining their enantiomers usually requires laborious and costly chiral separations.Moreover,their chiroptical activity is typically limited to the ultraviolet spectral range,which restricts their broader applicability.To overcome these limitations,a novel and efficient strategy for synthesizing optically active compounds through the incorporation of an optically pure binaphthol(BINOL)group onto the periphery of β-isoindigo based aza dipyrrometheneboron difluoride(aza-BODIPY)analogues(BIABs)was presented.The resulting(R)/(S)-BINOL-BIABs demonstrate exceptional photostability,deep-red emission,strong Cotton effect(Δε)and high absorbance dissymmetry factor(g_(abs)).Moreover,tunable circularly polarized luminescence(CPL)with high brightness in the deep-red region was achieved.This strategy offers straightforward procedures for synthesizing optically active compounds.
基金supported by the National Natural Science Foundation of China (No. 61775095)Natural Science Foundation of Jiangsu Province (No. BK20200092)+3 种基金Jiangsu Province Policy Guidance Plan (No. BZ2019014)Natural Science Foundation of Shandong Province (No. ZR2020KB018)‘Taishan scholars’ construction special fund of Shandong Provincethe High-Performance Computing Center in Nanjing Tech University for supporting the computational resources
文摘The small molecular second near-infrared(NIR-Ⅱ, 1000–1700 nm) dye-based nanotheranostics can concurrently combine deep-tissue photodiagnosis with in situ phototherapy, which occupies a vital position in the early detection and precise treatment of tumors. However, the development of small molecular NIR-Ⅱ dyes is still challenging due to the limited electron acceptors and cumbersome synthetic routes.Herein, we report a novel molecular electron acceptor, boron difluoride formazanate(BDF). Based on BDF, a new small molecular NIR-Ⅱ dye BDF1005 is designed and synthesized with strong NIR-I absorption at 768 nm and bright NIR-Ⅱ peak emission at 1034 nm. In vitro and in vivo experiments demonstrate that BDF1005-based nanotheranostics can be applied for NIR-Ⅱ fluorescence imaging-guided photothermal therapy of 4T1 tumor-bearing mice. Under 808 nm laser irradiation, tumor growth can be effectively inhibited. This work opens up a new road for the exploitation of NIR-Ⅱ small molecular dyes for cancer phototheranostics.
基金financially supported by the National Natural Science Foundation of China(Nos.21772096 and 22071116)the National Key Research and Development Program of China(No.2017YFD020030202)。
文摘Herein we report a new general method for one-step synthesis of four kinds of fluoroiodane(Ⅲ)reagents by treating the corresponding aryl iodides with silver difluoride(AgF_(2)).This is the first method applicable for the synthesis of all four fluoroiodane(Ⅲ)reagents including p-iodotoluene difluoride(1),fluoro-benziodoxole(2),fluoro-benziodoxolone(3),and fluoro-N-acetylbenziodazole(4).AgF_(2)was firstly employed in the direct oxidative fluorination of iodobenzene and thus has shown its outstanding oxidation and fluorine-transfer ability.The use of AgF_(2)has improved the synthesis of fluoroiodane(Ⅲ)reagents by shortening the reaction steps,avoiding the use of hazardous reagents,and simplifying the experimental operations.It was worth noting that we have developed the first one-step direct synthetic method for 3,while 3 can only be synthesized through Cl→F ligand exchange reaction previously.
基金supported by the State Key Laboratory of Pulp and Paper Engineering (2024ZD06)the Natural Science Foundation of Guangdong Province (2024B1515040023)+2 种基金the National Natural Science Foundation of China (52173005)the GJYC Program of Guangzhou(2024D03J0002)the 111 Project (B18023)。
文摘Developing safe and high-performance solid polymer electrolytes(SPEs) remains a critical challenge for all-solid-state batteries.Among various polymer materials,poly(ethylene oxide)(PEO) is most widely studied,while poly(vinylidene fluoride)(PVDF)has also attracted great interest recently.However,the intrinsic disadvantages of single polymers make them hardly meet the demands for practical applications.Physical blending of different types of SPEs is a simple and straightforward strategy to optimize their performance.Unfortunately,the direct blending of PEO and PVDF(or PVDF derivatives) usually leads to macrophase separation and fails to couple together.Herein,we designed and synthesized PEO-based block copolymers as compatibilizers to prevent macroscopic phase separation in PVDF/PEO blends.By tuning the interfacial compatibility,continuous nanostructures with high optical transparency are constructed through the microphase segregation.The obtained SPEs combine the merits of high mechanical modulus(380 MPa),high ionic conductivity(2.0 × 10^(-4)S cm^(-1),30 ℃),large transference number(0.60),and electrochemical stability(4.5 V).This simple and efficient chemical modification approach sheds light on alternative solutions for designing high-performance SPEs.
基金supported by the Basic Science Center Program of NSFC under Grant No.51788104NSFC projects under Grant Nos.51532002,51572141,and 51625202financial support within the project 03XP0177A funded by BMBF with the cluster of competence FESTBATT.
文摘Bulk-type all-solid-state batteries(ASSBs)using sulfide solid electrolyte are considered as a promising alternative to commercial lithium-ion batteries owing to their high energy density and safety.However,cell energy density is often comparatively low due to use of a thick solid electrolyte separator and a lithium alloy as anode.For achieving high-performance ASSBs,creating a thin free-standing electrolyte with high-conductivity and good cycling stability against lithium anode is essential.In this work,we present Li_(6)PS_(5)Cl/poly(vinylidene difluoride)(LPSCl/PVDF)composite electrolytes prepared by a slurry method.The influence of the PVDF content on the microstructure,morphology,ionic conductivity and activation energy of the LPSCl/PVDF electrolytes is systematically investigated.Free-standing LPSCl/PVDF membranes with a thickness of 100-120 mm and a high ionic conductivity of about 1·10^(-3) S cm^(-1) at 25℃ are obtained.After adding PVDF to the LPSCl electrolyte,the cycling stability of the LPSCl electrolyte against lithium metal improves significantly.Therefore,LPSCl/PVDF composite electrolytes are promising candidates to be used in ASSBs.
基金Project supported by the National Natural Science Foundation of China.
文摘The dynamic process of the ionic valence changing from Eu^(2+) to Eu^(3+) in EuF_2 at high temperature has been investigated by ESCA, high,temperature X-ray diffraction, high temperature spectrum, high temperature magnetic Isusceptibility and Mssbauer spectrum. It has been shown that the formed Eu^(3+) exists in different compounds when EuF_2 is heated to high temperature in different atmospheres. In air, Eu^(3+) exists in the form of hexagonal EuOF, in nitrogen, in the form of orthogonal EuF_3 and non-hexagon EuOF. This is because decomposition or disproportionation of EuF_2 is different with different atmospheres. The magnetic susceptibility measurement showed quantitatively that the change rate from Eu^(2+) to Eu^(3+) is about 95% in air, and about 75% in nitrogen when it is heated to 900℃. A small amount of Eu^(2+) coexists with Eu^(3+) in the final product.
基金the financial support by the National Science Foundation under PREM grant DMR 1523577the IIT startup funds (YM)+1 种基金the United States-India Education Foundation (USIEF, India)the Institute of International Education (IIE, USA) for his Fulbright Nehru Postdoctoral Fellowship (Award# 2268/FNPDR/2017)。
文摘Exploring lanthanide doped materials and their high-pressure optical properties is important from the perspective of designing pressure sensors, piezoelectric materials, scintillators, and optoelectronic devices, just to mention a few. Understanding the high-pressure optical properties of polymeric fibrous mats provides significant advantages in terms of flexibility, tunability, facile processability, and malleability. In this work, we have developed flexible polyvinylidene difluoride(PVDF) fibrous mats doped with an Eu^(3+) source of Eu(NO_(3))_(3)·5H_(2)O(EN-PF) or Eu_(2)(SO_(4))_(3)(ES-PF) by a Forcespinning■ method. Microstructural analysis of these two systems indicates that Eu(NO_(3))_(3)·5H_(2)O and Eu_(2)(SO_(4))_(3) are homogeneously distributed and dispersed into the PVDF matrix. Fiber formation promotes a β-phase PVDF. Eu^(3+) doping increases the β-phase. Its fraction is larger for the ES-PF mats. To understand their high-pressure optical properties, their photoluminescence spectra have been taken at various pressures up to 58 GPa in a diamond anvil cell. High-pressure luminescence illustrates a clear change in asymmetry ratio, peak intensity, peak breadth, color coordinate, and color temperature of Eu^(3+) ions from both EN-PF and ES-PF with a different extent of changes. Specifically, Eu^(3+) ions in the ES-PF mats switch from asymmetric to symmetric environment as pressure increases. Those in the EN-PF mats present symmetric environment for all tested pressures. Both of the Eu^(3+) doped PVDF systems present irreversible changes. Therefore,the EN-PF fibrous mats present an opportunity to make pressure induced red-orange-yellow tunable phosphors for multifunctional applications.
文摘Fluoride processing of natural ilmenite with the use of ammonium hydrogen difluoride (NH4HF2) as an effective fluorinating agent is suggested. Chemistry, composition, structure, thermal and hydrolytic properties of fluorination products were investigated. Ammonium fluoro- and oxofluorotitanates are suitable for preparing of titanium dioxide as pigmentary product or as doped by nitrogen and fluorine.
基金funded by National Natural Science Foundation of China(22278023,22208010)Beijing Municipal Science and Technology Planning Project(Z221100002722002)+3 种基金Bingtuan Science and Technology Program(2022DB025)Beijing Natural Science Foundation(2222015)Sinopec Group(323034)the long-term from the Ministry of Finance and the Ministry of Education of PRC。
文摘An anion exchange membrane(AEM)is generally expected to possess high ion exchange capacity(IEC),low water uptake(WU),and high mechanical strength when applied to electrodialysis desalination.Among different types of AEMs,semi-interpenetrating polymer networks(SIPNs)have been suggested for their structural superiorities,i.e.,the tunable local density of ion exchange groups for IEC and the restrained leaching of hygroscopic groups by insolubility for WU.Unfortunately,the conventional SIPN AEMs still struggle to balances IEC,WU,and mechanical strength simultaneously,due to the lack of the compact crosslinking region.In this work,we proposed a novel SIPN structure of polyvinylidene difluoride/polyvinylimidazole/1,6-dibromohexane(PVDF/PVIm/DBH).On the one hand,DBH with two cationic groups of imidazole groups are introduced to enhance the ion conductivity,which is different from the conventional monofunctional modifier with only one cationic group.On the other hand,DBH has the ability to bridge with PVIm,where the mechanical strength of the resulting AEM is increased by the increase of crosslinking degree.Results show that a low WU of 38.1%to 62.6%,high IEC of 2.12—2.22 mmol·g^(-1),and excellent tensile strength of 3.54—12.35 MPa for PVDF/PVIm/DBH membrane are achieved.This work opens a new avenue for achieving the high-quality AEMs.
基金The National Natural Science Foundation of China(No.52375563)the Science and Technology on Avionics Integration Laboratory(No.201913069001,20200055069001).
文摘To enhance the piezoelectric performance of piezoelectric polymer thin films in general,hybrid polyvinylidene difluoride(PVDF)and nanosized barium titanate(BaTiO_(3))piezoelectric films were prepared and their piezoelectric performance examined.The hybrid nanofibers were fabricated via electrospinning at an external voltage of 15 kV.The nonwoven fabrics were collected using a roller collection device,and their morphological structures were analyzed via scanning electron microscopy.The crystal structures of these piezoelectric films were characterized via micro-Raman spectroscopy.β-phase of the composite nanofiber membrane almost increased to twice owing to the addition of BaTiO_(3)nanoparticles.Compared with pure,electrospun PVDF piezoelectric film,the piezoelectric characteristics of the hybrid piezoelectric films were considerably enhanced because of the additional BaTiO_(3)nanoparticles.The maximum instantaneous open-circuit voltage of the hybrid PVDF-BaTiO_(3)nanofibers film can be high up to 80 V.The high-performance hybrid piezoelectric films exhibited notable prospects for applications in wearable electronic textiles.
基金supported by the Swiss National Science Foundation(310030_192757)the European Research Council(ERC-2015-CoG-682379)+2 种基金The development of the ultra-wideband ultrasonic antenna and the in vivo optoacoustic experiments were supported by the grants from the Russian Science Foundation(18-45-06006)the Helmholtz Association(HRSF-0020)The development of numerical algorithms for enhancement of angiographic optoacoustic images was partially supported by the grant from the Russian Science Foundation(19-75-10055)。
文摘Owing to its unique ability to capture volumetric tomographic information with a single light flash,optoacoustic(OA)tomography has recently demonstrated ultrafast imaging speeds ultimately limited by the ultrasound time-of-flight.The method's scalability and the achievable spatial resolution are yet limited by the narrow bandwidth of piezo-composite arrays currently employed for OA signal detection.Here we report on the first implementation of high-density spherical array technology based on flexible polyvinylidene difluoride films featuring ultrawideband(0.3-40 MHz)sub mm^(2)area elements,thus enabling real-time multi-scale volumetric imaging with 22-35μm spatial resolution,superior image fidelity and over an order of magnitude signal-to-noise enhancement compared to piezo-composite equivalents.We further demonstrate five-dimensional(spectroscopic,time-resolved,volumetric)imaging capabilities by visualizing fast stimulus-evoked cerebral oxygenation changes in mice and performing real-time functional angiography of deep human micro-vasculature.The new technology thus leverages the true potential of OA for quantitative high-resolution visualization of rapid bio-dynamics across scales.
基金This work was primarily supported by the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University(Faculty Grant SFO-Mat-LiU)(No.2009-00971)the Knut and Alice Wallenberg Foundation(No.KAW 2022-0383,Piezotex).
文摘Polyvinylidene difluoride(PVDF)derivatives in metal/PVDF/metal(MPM)sandwich structures have been studied extensively since 1969.Cousin copolymers of the same family have been discovered with fascinating piezoelectric,pyroelectric,electrocaloric,and ferroelectric properties.Solution processing,flexibility,lightweight,and thermal stability make this class of materials complementary to inorganics.Thus,PVDF based polymers potentially compete with inorganic materials for a broad range of technologies such as energy generators,loudspeakers,coolers,and memories.However,the stable non-electroactiveα-phase and hydrophobic nature of PVDF are the main barriers for developoing high performing and robust MPM devices in electronic applications.In this review,we present an up-to-date overview on different methods to induce the electroactiveβ-phase and improve the adhesion strength with metals to ensure robust and durable MPM devices.We go through advantages and disadvantages of several methods and pinpoint future opportunities in this research area.A special attention is paid to wearable piezoelectric nanogenerators for energy harvesting from human body motion,where flexible PVDF derivatives are compared with rigid piezoelectric ceramics.While the piezoelectric coefficient of PVDF(d_(33)~24–34 pm/V)is one order lower than ceramic materials,novel co-polymers of PVDF display d_(33)>1000 pm/V upon bias.This shows promise to bring piezoelectrics to flexible and large-area applications such as smart textiles.We also discussed challenges to improve wearability,such as light weight,breathability,and flexibility.
基金Project supported by the National Natural Science Foundation of China （Nos. 21032006, 20172064）, and the QT Program, Shanghai Natural Science Council.
文摘A novel and facile preparation of l,l-difluoroallyl substituted five-membered lactones or pyrrolidines in mod- erate yields through direct double electrophilic fluorination of 4,5-allenoic acids or tosylamides with SelectfluorTM F-TEAD-BF4 is described.
基金Project supported by the National Natural Science Foundation of China.
文摘Nonstoichiometric series SmF_x (2.0≤x≤3.0) have been synthesized by reduction of samarium trifluoride with hydrogen for several times, and the stoichiometric samarium difluoride has been obtained. The structure of nonstoichiometric samarium fluoride series and the valency of samarium ion are briefly discussed. The valent change process of samarium ion at high temperatures in different atmospheres is investigated.
