The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves...The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the problem.Two types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)layer.The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated.The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)binder.Due to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,respectively.Furthermore,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers.These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.展开更多
3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have...3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion.展开更多
α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were ...α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin polymerization.In this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene polymerization.These nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 carbons.More importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.展开更多
Under the condition of solvothermal synthesis,the viologen ligand 1,1′-bis(3-carboxyphenyl)-(4,4′-bipyri-dine)dichloride(H_(2)bcbpy·2Cl)and KI are coordinated with the metal cadmium ions.A case of thermochromic...Under the condition of solvothermal synthesis,the viologen ligand 1,1′-bis(3-carboxyphenyl)-(4,4′-bipyri-dine)dichloride(H_(2)bcbpy·2Cl)and KI are coordinated with the metal cadmium ions.A case of thermochromic coor-dination polymer[Cd(bcbpy)I_(2)]·2H_(2)O(1)was constructed.Complex 1 displays a 1D chain structure and exhibits thermochromic behavior.Under different temperature stimulation,the complex(ground)slowly changed from green to yellow-green,and with the increase of temperature,the color of complex 1 gradually deepened,and finally became orange-yellow.Therefore,complex 1 was prepared as a thermochromic film.In addition,we also performed electrochemical tests on complex 1,which showed that the complex is a semiconductor material.CCDC:2391802.展开更多
We report five coordination polymers(CPs)based on fluorescent ligands[1,6-di(1H-imidazol-1-yl)pyrene(dip),9,10-di(1H-imidazol-1-yl)anthracene(dia)]and anionic ligands[cyclohexane-1,4-dicarboxylic acid(H_(2)cda),campho...We report five coordination polymers(CPs)based on fluorescent ligands[1,6-di(1H-imidazol-1-yl)pyrene(dip),9,10-di(1H-imidazol-1-yl)anthracene(dia)]and anionic ligands[cyclohexane-1,4-dicarboxylic acid(H_(2)cda),camphoric acid(H_(2)cpa)].In[Cd(dip)(cda)]·4H_(2)O}_(n)(1),the Cd^(2+)ions,acting as tetrahedral nodes,are linked by dipand cda^(2-)ligands with four Cd^(2+)ions into five-fold interpenetrating network array of topology of dia.In{[Cd(dip)(cpa)]·4H_(2)O}_(n)(2),the Cd^(2+)ions,acting as a 4-connector,are linked by cpa^(2-)and dip ligands into a 3D framework ofcds topology.In{[Ni(dia)_(2)Cl_(2)]·DMF}_(n)(3),the Ni^(2+)ion is linked by four dia ligands into a layer structure,and 1Dchannels of a cross-section of 1.35 nm×0.96 nm are formed.In{[Cd(dia)_(2)(H_(2)O)_(2)](NO_(3))_(2)·2DMSO}n(4),the dia ligandsconnected Cd^(2+)ions into a 2D layer,and 1D channels are formed between adjacent layers with a cross-section of0.87 nm×0.43 nm.In[Zn(dip)Cl_(2)]_(n)(5),the Zn^(2+)ion is linked by dip ligands into an infinite 1D chain.The infrared,thermal gravimetric,and fluorescent emission data were collected and analyzed for these coordination polymers.CCDC:2356055,1;2440075,2;2356057,3;2356057,4;2356059,5.展开更多
Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1....Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1.5)Cl_(3)]·5H_(2)O}n(2)are framework isomers,which both contain zigzag chains formed by DPA,Zn^(2+),and Cl-.The zigzag chains in 1 are further assembled by C—H…Cl interactions into layers,and these layers exhibit two different orientations,displaying a rare 2D to 3D interpenetration mode.The zigzag chains in 2 are parallelly arranged.{[Zn_(3)(DPA)_(3)Br_(6)]·2DMF·_(1.5)H_(2)O}n(3)is isostructural to 2.3 was obtained using ZnBr_(2)instead of ZnCl_(2).[M(DPA)(formate)_(2)(H_(2)O)_(2)]n[M=Co(4),Cu(5)]are isostructural,contain chain structures formed by DPA,Cu^(2+)/Co^(2+),and for-mate ions,which were formed in situ in the solvothermal reaction.{[Zn(DIP)_(2)Cl]ClO_(4)}n(6)contains a layer structure formed by DIP and Zn^(2+).Free DPA and DIP ligands exhibited high fluorescence at room temperature,and coordina-tion polymers 3 and 6 displayed enhanced fluorescent emissions.展开更多
Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubri...Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.展开更多
A novel coordination polymer(CP){[Cd_(2)(L)(1,4-bimb)_(1.5)(DMF)_(2)]·DMF}n(1)(H_(4)L=5,5'-[1,1'-biphenyl-4,4'-diylbis(oxy)]diisophthalic acid,1,4-bimb=1,4-bis(imidazole-1-ylmethyl)-benzene)has been d...A novel coordination polymer(CP){[Cd_(2)(L)(1,4-bimb)_(1.5)(DMF)_(2)]·DMF}n(1)(H_(4)L=5,5'-[1,1'-biphenyl-4,4'-diylbis(oxy)]diisophthalic acid,1,4-bimb=1,4-bis(imidazole-1-ylmethyl)-benzene)has been designed and synthesized through solvothermal reaction.Structural analysis shows that Cd(Ⅱ)is connected by H4L and 1,4-bimb to form a 2D network,and 1,4-bimb further expands the 2D network into a 3D framework.CP 1 can be used as an excellent fluorescence sensor for Fe^(3+)and 4-nitrophenol(4-NP),with low detection limits and good anti-interference.The detection limits of Fe^(3+)and 4-NP were 0.034 and 0.031μmol·L^(-1),respectively.In addition,the fluorescence quenching mechanism was studied.1 was successfully applied to determine Fe^(3+)and 4-NP content in the Yanhe River water sample.CCDC:2351092.展开更多
Traditional polymeric photocatalysts are typically constructed using aromatic building blocks to enhanceπ-conjugation.However,their inherent hydrophobicity and rigid structure lead to poor dispersibility in aqueous s...Traditional polymeric photocatalysts are typically constructed using aromatic building blocks to enhanceπ-conjugation.However,their inherent hydrophobicity and rigid structure lead to poor dispersibility in aqueous solutions,resulting in significant optical losses and exciton recombination.In this study,two series of six novel polymer photocatalysts(FLUSO,FLUSO-PEG10,FLUSO-PEG30;CPDTSO,CPDTSO-PEG10,CPDTSO-PEG30)are designed and synthesized by incorporating the hydrophilic,non-conjugated polyethylene glycol(PEG)chain,into both the main and side chains of polymers.By precisely optimizing the ratio of hydrophilic PEG segments,the water dispersibility is significantly improved while the light absorption capability of the polymer photocatalysts is well maintained.The experimental results confirm that the optimized FLUSO-PEG10 exhibits excellent photocatalytic hydrogen evolution rate,reaching up to 33.9 mmol/(g·h),which is nearly three times higher than that of fullyπ-conjugated counterparts.Water contact angles and particle size analyses reveal that incorporating non-conjugated segments into the main chains enhances the capacitance of the polymer/water interface and reduces particle aggregation,leading to improved photocatalyst dispersion and enhanced charge generation.展开更多
Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfull...Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2.展开更多
A coordination polymer{[Cd(H_(2)dpa)(bpy)]·3H_(2)O}_(n)(Cd-CP)was designed and hydrothermal synthesized based on 4-(2,4-dicarboxyphenoxy)phthalic acid(H_(4)dpa),2,2'-bipyridine(bpy)and Cd(NO_(3))_(2)·4H_...A coordination polymer{[Cd(H_(2)dpa)(bpy)]·3H_(2)O}_(n)(Cd-CP)was designed and hydrothermal synthesized based on 4-(2,4-dicarboxyphenoxy)phthalic acid(H_(4)dpa),2,2'-bipyridine(bpy)and Cd(NO_(3))_(2)·4H_(2)O.The structure was characterized by single-crystal X-ray diffraction,powder X-ray diffraction,elemental analysis,and infrared spectroscopy.Cd-CP belongs to the monoclinic crystal system with the P2_1/c space group and performs in a 1D double-chain structure.The adjacent double chains further form a 3D supramolecular network structure through hydrogen bonding.Thermogravimetric analysis shows that Cd-CP has good thermal stability.Fluorescence analysis showed that Cd-CP had good choosing selectively and was sensitive to metal ions(Fe^(3+)and Zn^(2+)),2,4,6-trinitrophenylhydrazine(TRI),and pyrimethanil(Pth).Interestingly,when Cd-CP was used for fluorescence detection of metal ions,it was found to have a fluorescence quenching effect on Fe^(3+)but had an obvious enhancement effect on Zn^(2+).Therefore,we designed an“on-off-on”logic gate.In addition,the mechanism of fluorescence sensing has been deeply explored.CCDC:2258625.展开更多
Recently,foamed polymers have been widely used in the repair of underground engineering disasters by grouting(trenchless technology)due to controllable gelation time and self-expansion.However,the grouting process bec...Recently,foamed polymers have been widely used in the repair of underground engineering disasters by grouting(trenchless technology)due to controllable gelation time and self-expansion.However,the grouting process becomes more complicated due to the complex geological conditions and the self-expansion of slurry.Therefore,this paper adopts a self-made visual experimental device with peripheral pressure and water plugging rate(WPR)monitoring functions to study the influence of main influencing parameters(particle size distribution,grouting amount and dynamic water pump pressure(DWPP))on the spatiotemporal distribution of slurry WPR and diffusion dynamic response(peripheral pressure).The results show that:When grouting amount is 563 g and DWPP is 0.013 MPa,the expansion force of the slurry in the diffusion process is dominant and can significantly change the local sand and gravel skeleton structure.When grouting amount is 563 g,DWPP is 0.013 MPa,and particle size distribution type isⅢ,the flow time of the polymer is shortened,the pores of the gravel are rapidly blocked.Then,the peripheral pressure decreases rapidly with the increase of the distance,and the time to reach the inflection point WPR is shortened.The instantaneous blockage of the pores leads to the delayed transmission of flow field blockage information.展开更多
This study investigates the potential of metal additives in acrylonitrile butadiene styrene(ABS)polymer fuel to enhance hybrid rocket motor(HRM)performance through computational analysis,Chemical Equilibrium with Appl...This study investigates the potential of metal additives in acrylonitrile butadiene styrene(ABS)polymer fuel to enhance hybrid rocket motor(HRM)performance through computational analysis,Chemical Equilibrium with Applications(CEA),software.ABS was selected as the base fuel due to its thermoplastic nature,which allows for the creation of complex fuel geometries through 3D printing,offering significant flexibility in fuel design.Hybrid rockets,which combine a solid fuel with a liquid oxidiser,offer advantages in terms of operational simplicity and safety.However,conventional polymer fuels often exhibit low regression rates and suboptimal combustion efficiencies.In this research,we evaluated a range of metal additives-aluminium(Al),boron(B),nickel(Ni),copper(Cu),and iron(Fe)-at chamber pressures ranging from 1 to 30 bar and oxidiser-to-fuel(O/F)ratios between 1.1 and 12,resulting in 1800 unique test conditions.The main performance parameters used to assess each formulation were characteristic velocity(C^(*))and adiabatic flame temperature.The results revealed that each test produced a different optimum O/F ratio,with most ratios falling between 4 and 6.The highest performance was achieved at a chamber pressure of 30 bar across all formulations.Among the additives,Al and B demonstrated significant potential for improved combustion performance with increasing metal loadings.In contrast,Fe,Cu,and Ni reached optimal performance at a minimum loading of 1%.Future work includes investigating B-Al metal composites as additives into the ABS base polymer fuel,and doing experimental validation tests where the metallised ABS polymer fuel is 3D printed.展开更多
Controlled release NPK compound fertilizers were prepared by means of in situ polymerization of monomers on the surface of fertilizer granules at room temperature. Methacrylate, α-methyl acrylic acid, and ethylene di...Controlled release NPK compound fertilizers were prepared by means of in situ polymerization of monomers on the surface of fertilizer granules at room temperature. Methacrylate, α-methyl acrylic acid, and ethylene dimethylacrylate were used as monomers, Dibenzoyl peroxide as initiator, and cobalt naphthenate, and triethyl amine as promoters. The structures of coating materials were characterized by IR spectra. The thermogravimetric analysis result indicated that the coating materials were of good thermal stability. The mean thickness of single coating measured with screw gauge was ca. 140 μm. The morphologies of uncoated and coated fertilizer granules analyzed by using scanning electron microscopy were changed from porosities and gullies to hills and plain. The release rate of coated compound fertilizers in water could be controlled by the hydrophicity and thickness of coating. The increase in coating hydrophicity caused the increase in release rate of fertilizer. The increase in thickness of coating slowed the release rate.展开更多
The core-shell 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-Trinitrotoluene(CL-20/TNT)composite was prepared by spray-drying method in which sensitive high energy explosive(CL-20)was coated with in...The core-shell 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-Trinitrotoluene(CL-20/TNT)composite was prepared by spray-drying method in which sensitive high energy explosive(CL-20)was coated with insensitive explosive(TNT).The structure and properties of different formulations of CL-20/TNT composite and CL-20/TNT mixture were characterized by scanning electron microscopy(SEM),Transmission electron microscopy(TEM),Laser particle size analyzer,X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),differential scanning calorimetry(DSC),impact sensitivity test and detonation performance.The results of SEM,TEM,XPS and XRD show that e-CL-20 particles are coated by TNT.When the ratio of CL-20/TNT is 75/25,core-shell structure is well formed,and thickness of the shell is about 20e30 nm.And the analysis of heat and impact show that with the increase of TNT content,the TNT coating on the core-shell composite material can not only catalyze the thermal decomposition of core material(CL-20),but also greatly reduce the impact sensitivity.Compared with the CL-20/TNT mixture(75/25)at the same ratio,the characteristic drop height of core-shell CL-20/TNT composite(75/25)increased by 47.6%and the TNT coating can accelerate the nuclear decomposition in the CL-20/TNT composites.Therefore,the preparation of the core-shell composites can be regarded as a unique means,by which the composites are characterized by controllable decomposition rate,high energy and excellent mechanical sensitivity and could be applied to propellants and other fields.展开更多
A facile and economical approach was developed for the large-scale production of powdered core-shell structured PTFE/Al (CS-PA) energetic materials through ultrasonic-assisted mixing. The low-cost micrometer-sized PTF...A facile and economical approach was developed for the large-scale production of powdered core-shell structured PTFE/Al (CS-PA) energetic materials through ultrasonic-assisted mixing. The low-cost micrometer-sized PTFE and Al particles were used as starting materials. Under high-power ultrasonic waves, the PTFE powder was dispersed into nano-to sub-micrometer-sized particles and then encapsulated the Al microparticles to form the core-shell structure. The heat of combustion, burning rate, and pressurization rate of the powdered CS-PA were measured. The thermal-initiated reaction behavior was further evaluated using thermogravimetry-differential scanning calorimetry. Subsequently, the bulk CS-PA with a uniform microstructure was obtained via cold isostatic pressing of the powdered CS-PA followed by vacuum sintering. For the bulk CS-PA, the quasi-static compression behavior was characterized, and the impact-initiated reaction processes were conducted using the Split Hopkinson Pressure Bar (SHPB) and evaluated by a high-speed camera. Compared to physically mixed PTFE/Al materials, the powdered and bulk CS-PA demonstrated enhanced thermal- and impact-initiated reaction characteristics respectively, proving the effectiveness of our approach for constructing core-shell structures.展开更多
Inspired by the phenomenon of superhydrophobic plants and animals in nature,1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)@copper stearate(CS)core-shell composites with similar properties was prepared.A rough shell layer...Inspired by the phenomenon of superhydrophobic plants and animals in nature,1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)@copper stearate(CS)core-shell composites with similar properties was prepared.A rough shell layer on the surface of the HMX was observed by scanning electron microscopy(SEM),and a series of in-depth characterization confirmed the successful generation of CS and the coreshell structure of the samples.Differential scanning calorimeter(DSC)proves that the crystal transition temperature(204℃)and high temperature decomposition exothermal temperature(284℃)of HMX@CS is almost unchanged compared with pure HMX,which means HMX and CS have good compatibility.Then,the H50 of the samples also increased continuously(16.6 cm→33.7 cm)when the CS shell content increased from 1%to 5%,indicating that the CS shell has a certain buffering performance,and CS will absorb some heat and melt under the stimulation of impact due to its low melting point,which improved impact sensitivity of HMX effectively further.Moreover,HMX@CS has excellent hydrophobic and oleophilic performance,shows excellent wettability with lipid binder,and samples with appropriate CS shell content can continue to combustion stably after covering water.This waterproof and low sensitivity coating provides a new way for the development of multifunctional energetic materials.展开更多
Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesi...Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.展开更多
基金the support for this work by National Natural Science Foundation of China(Grant Nos.22175139 and 22105156)。
文摘The weak interface interaction and solid-solid phase transition have long been a conundrum for 1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane(HMX)-based polymer-bonded explosives(PBX).A two-step strategy that involves the pretreatment of HMX to endow—OH groups on the surface via polyalcohol bonding agent modification and in situ coating with nitrate ester-containing polymer,was proposed to address the problem.Two types of energetic polyether—glycidyl azide polymer(GAP)and nitrate modified GAP(GNP)were grafted onto HMX crystal based on isocyanate addition reaction bridged through neutral polymeric bonding agent(NPBA)layer.The morphology and structure of the HMX-based composites were characterized in detail and the core-shell structure was validated.The grafted polymers obviously enhanced the adhesion force between HMX crystals and fluoropolymer(F2314)binder.Due to the interfacial reinforcement among the components,the two HMX-based composites exhibited a remarkable increment of phase transition peak temperature by 10.2°C and 19.6°C with no more than 1.5%shell content,respectively.Furthermore,the impact and friction sensitivity of the composites decreased significantly as a result of the barrier produced by the grafted polymers.These findings will enhance the future prospects for the interface design of energetic composites aiming to solve the weak interface and safety concerns.
基金funded by the National Natural Science Foundation of China(Grant No.06101213)the National Natural Science Foundation of China(Grant No.22105160).
文摘3D printing technology enhances the combustion characteristics of hybrid rocket fuels by enabling complex geometries. However, improvements in regression rates and energy properties of monotonous 3D printed fuels have been limited. This study explores the impact of poly(vinylidene fluoride) and polydopamine-coated aluminum particles on the thermal and combustion properties of 3D printed hybrid rocket fuels. Physical self-assembly and anti-solvent methods were employed for constructing composite μAl particles. Characterization using SEM, XRD, XPS, FTIR, and μCT revealed a core-shell structure and homogeneous elemental distribution. Thermal analysis showed that PVDF coatings significantly increased the heat of combustion for aluminum particles, with maximum enhancement observed in μAl@PDA@PVDF(denoted as μAl@PF) at 6.20 k J/g. Subsequently, 3D printed fuels with varying pure and composite μAl particle contents were prepared using 3D printing. Combustion tests indicated higher regression rates for Al@PF/Resin composites compared to pure resin, positively correlating with particle content. The fluorocarbon-alumina reaction during the combustion stage intensified Al particle combustion, reducing residue size. A comprehensive model based on experiments provides insights into the combustion process of PDA and PVDF-coated droplets. This study advances the design of 3D-printed hybrid rocket fuels, offering strategies to improve regression rates and energy release, crucial for enhancing solid fuel performance for hybrid propulsion.
基金supported by the National Natural Science Foundation of China(52203016)the USTC Research Funds of the Double First-Class Initiative(YD9990002018)+3 种基金the Overseas Students Innovation and Entrepreneurship Support Program Project of Anhui Province(2021LCX022)the Key R&D Projects in Anhui Province(2022i01020012)the Natural Science Foundation of Hefei(2022039)the Excellent Research and Innovation Team Project of Anhui Province(2022AH010001).
文摘α-Diimide catalysts have attracted widespread attention due to their unique chain walking characteristics.A series ofα-diimide nickel/palladium catalysts with different electronic effects and steric hindrances were designed and synthesized for olefin polymerization.In this work,we synthesized a series of asymmetricα-diimide nickel complexes with different steric hindrances and used them for ethylene polymerization.These nickel catalysts have high ethylene polymerization activity,up to 6.51×10^(6)g·mol^(−1)·h^(−1),and the prepared polyethylene has a moderate melting point and high molecular weight(up to 38.2×10^(4)g·mol^(−1)),with a branching density distribution between 7 and 94 branches per 1000 carbons.More importantly,the polyethylene prepared by these catalysts exhibits excellent tensile properties,with strain and stress reaching 800%and 30 MPa,respectively.
文摘Under the condition of solvothermal synthesis,the viologen ligand 1,1′-bis(3-carboxyphenyl)-(4,4′-bipyri-dine)dichloride(H_(2)bcbpy·2Cl)and KI are coordinated with the metal cadmium ions.A case of thermochromic coor-dination polymer[Cd(bcbpy)I_(2)]·2H_(2)O(1)was constructed.Complex 1 displays a 1D chain structure and exhibits thermochromic behavior.Under different temperature stimulation,the complex(ground)slowly changed from green to yellow-green,and with the increase of temperature,the color of complex 1 gradually deepened,and finally became orange-yellow.Therefore,complex 1 was prepared as a thermochromic film.In addition,we also performed electrochemical tests on complex 1,which showed that the complex is a semiconductor material.CCDC:2391802.
文摘We report five coordination polymers(CPs)based on fluorescent ligands[1,6-di(1H-imidazol-1-yl)pyrene(dip),9,10-di(1H-imidazol-1-yl)anthracene(dia)]and anionic ligands[cyclohexane-1,4-dicarboxylic acid(H_(2)cda),camphoric acid(H_(2)cpa)].In[Cd(dip)(cda)]·4H_(2)O}_(n)(1),the Cd^(2+)ions,acting as tetrahedral nodes,are linked by dipand cda^(2-)ligands with four Cd^(2+)ions into five-fold interpenetrating network array of topology of dia.In{[Cd(dip)(cpa)]·4H_(2)O}_(n)(2),the Cd^(2+)ions,acting as a 4-connector,are linked by cpa^(2-)and dip ligands into a 3D framework ofcds topology.In{[Ni(dia)_(2)Cl_(2)]·DMF}_(n)(3),the Ni^(2+)ion is linked by four dia ligands into a layer structure,and 1Dchannels of a cross-section of 1.35 nm×0.96 nm are formed.In{[Cd(dia)_(2)(H_(2)O)_(2)](NO_(3))_(2)·2DMSO}n(4),the dia ligandsconnected Cd^(2+)ions into a 2D layer,and 1D channels are formed between adjacent layers with a cross-section of0.87 nm×0.43 nm.In[Zn(dip)Cl_(2)]_(n)(5),the Zn^(2+)ion is linked by dip ligands into an infinite 1D chain.The infrared,thermal gravimetric,and fluorescent emission data were collected and analyzed for these coordination polymers.CCDC:2356055,1;2440075,2;2356057,3;2356057,4;2356059,5.
文摘Six coordination polymers based on 9,10-di(pyridine-4-yl)-anthracene(DPA)and 1,6-di(1H-imidazol-1-yl)pyrene(DIP)were obtained by solvothermal reactions.{[Zn(DPA)Cl_(2)]·DMF·2H_(2)O}n(1)and{[Zn_(1.5)(DPA)_(1.5)Cl_(3)]·5H_(2)O}n(2)are framework isomers,which both contain zigzag chains formed by DPA,Zn^(2+),and Cl-.The zigzag chains in 1 are further assembled by C—H…Cl interactions into layers,and these layers exhibit two different orientations,displaying a rare 2D to 3D interpenetration mode.The zigzag chains in 2 are parallelly arranged.{[Zn_(3)(DPA)_(3)Br_(6)]·2DMF·_(1.5)H_(2)O}n(3)is isostructural to 2.3 was obtained using ZnBr_(2)instead of ZnCl_(2).[M(DPA)(formate)_(2)(H_(2)O)_(2)]n[M=Co(4),Cu(5)]are isostructural,contain chain structures formed by DPA,Cu^(2+)/Co^(2+),and for-mate ions,which were formed in situ in the solvothermal reaction.{[Zn(DIP)_(2)Cl]ClO_(4)}n(6)contains a layer structure formed by DIP and Zn^(2+).Free DPA and DIP ligands exhibited high fluorescence at room temperature,and coordina-tion polymers 3 and 6 displayed enhanced fluorescent emissions.
文摘Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.
文摘A novel coordination polymer(CP){[Cd_(2)(L)(1,4-bimb)_(1.5)(DMF)_(2)]·DMF}n(1)(H_(4)L=5,5'-[1,1'-biphenyl-4,4'-diylbis(oxy)]diisophthalic acid,1,4-bimb=1,4-bis(imidazole-1-ylmethyl)-benzene)has been designed and synthesized through solvothermal reaction.Structural analysis shows that Cd(Ⅱ)is connected by H4L and 1,4-bimb to form a 2D network,and 1,4-bimb further expands the 2D network into a 3D framework.CP 1 can be used as an excellent fluorescence sensor for Fe^(3+)and 4-nitrophenol(4-NP),with low detection limits and good anti-interference.The detection limits of Fe^(3+)and 4-NP were 0.034 and 0.031μmol·L^(-1),respectively.In addition,the fluorescence quenching mechanism was studied.1 was successfully applied to determine Fe^(3+)and 4-NP content in the Yanhe River water sample.CCDC:2351092.
文摘Traditional polymeric photocatalysts are typically constructed using aromatic building blocks to enhanceπ-conjugation.However,their inherent hydrophobicity and rigid structure lead to poor dispersibility in aqueous solutions,resulting in significant optical losses and exciton recombination.In this study,two series of six novel polymer photocatalysts(FLUSO,FLUSO-PEG10,FLUSO-PEG30;CPDTSO,CPDTSO-PEG10,CPDTSO-PEG30)are designed and synthesized by incorporating the hydrophilic,non-conjugated polyethylene glycol(PEG)chain,into both the main and side chains of polymers.By precisely optimizing the ratio of hydrophilic PEG segments,the water dispersibility is significantly improved while the light absorption capability of the polymer photocatalysts is well maintained.The experimental results confirm that the optimized FLUSO-PEG10 exhibits excellent photocatalytic hydrogen evolution rate,reaching up to 33.9 mmol/(g·h),which is nearly three times higher than that of fullyπ-conjugated counterparts.Water contact angles and particle size analyses reveal that incorporating non-conjugated segments into the main chains enhances the capacitance of the polymer/water interface and reduces particle aggregation,leading to improved photocatalyst dispersion and enhanced charge generation.
文摘Two new transition-metal coordination polymers,{[Cd(oba)(L)_(2)]·H_(2)O}_n(1)and[Cd(4-nph)(L)_(2)]_n(2)(H_(2)oba=4,4'-oxydibenzoic acid,4-H_(2)nph=4-nitrophthalic acid,L=2,2'-biimidazole),were successfully synthesized under hydrothermal conditions and characterized structurally by IR spectroscopy,elemental analyses,single-crystal X-ray diffraction,powder X-ray diffraction,and thermogravimetric analysis.The results of single-crystal X-ray diffraction show that complex 1 presents a 1D zigzag chain structure and further extends to a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.Meanwhile,complex 2 has a zero-dimensional structure and also extends to form a 2D network through N—H…O hydrogen bonds andπ-πstacking interactions.In addition,both 1and 2 exhibited luminescent properties in the solid state.Furthermore,quantum chemical calculations were carried out on the"molecular fragments"extracted from the crystal structures of 1 and 2 using the PBE0/LANL2DZ method constructed by the Gaussian 16 program.The calculated values signify a significant covalent interaction between the coordination atoms and the Cd(Ⅱ)ions.CCDC:2332173,1;2332176,2.
文摘A coordination polymer{[Cd(H_(2)dpa)(bpy)]·3H_(2)O}_(n)(Cd-CP)was designed and hydrothermal synthesized based on 4-(2,4-dicarboxyphenoxy)phthalic acid(H_(4)dpa),2,2'-bipyridine(bpy)and Cd(NO_(3))_(2)·4H_(2)O.The structure was characterized by single-crystal X-ray diffraction,powder X-ray diffraction,elemental analysis,and infrared spectroscopy.Cd-CP belongs to the monoclinic crystal system with the P2_1/c space group and performs in a 1D double-chain structure.The adjacent double chains further form a 3D supramolecular network structure through hydrogen bonding.Thermogravimetric analysis shows that Cd-CP has good thermal stability.Fluorescence analysis showed that Cd-CP had good choosing selectively and was sensitive to metal ions(Fe^(3+)and Zn^(2+)),2,4,6-trinitrophenylhydrazine(TRI),and pyrimethanil(Pth).Interestingly,when Cd-CP was used for fluorescence detection of metal ions,it was found to have a fluorescence quenching effect on Fe^(3+)but had an obvious enhancement effect on Zn^(2+).Therefore,we designed an“on-off-on”logic gate.In addition,the mechanism of fluorescence sensing has been deeply explored.CCDC:2258625.
基金Project(2022YFC3801000)supported by the National Key Research and Development Program of ChinaProject(232300421064)supported by the Natural Science Foundation of Henan Province,China+1 种基金Project(241111322700)supported by the Key Research and Development Projects in Henan Province,ChinaProject(52008379)supported by the National Natural Science Foundation of China。
文摘Recently,foamed polymers have been widely used in the repair of underground engineering disasters by grouting(trenchless technology)due to controllable gelation time and self-expansion.However,the grouting process becomes more complicated due to the complex geological conditions and the self-expansion of slurry.Therefore,this paper adopts a self-made visual experimental device with peripheral pressure and water plugging rate(WPR)monitoring functions to study the influence of main influencing parameters(particle size distribution,grouting amount and dynamic water pump pressure(DWPP))on the spatiotemporal distribution of slurry WPR and diffusion dynamic response(peripheral pressure).The results show that:When grouting amount is 563 g and DWPP is 0.013 MPa,the expansion force of the slurry in the diffusion process is dominant and can significantly change the local sand and gravel skeleton structure.When grouting amount is 563 g,DWPP is 0.013 MPa,and particle size distribution type isⅢ,the flow time of the polymer is shortened,the pores of the gravel are rapidly blocked.Then,the peripheral pressure decreases rapidly with the increase of the distance,and the time to reach the inflection point WPR is shortened.The instantaneous blockage of the pores leads to the delayed transmission of flow field blockage information.
文摘This study investigates the potential of metal additives in acrylonitrile butadiene styrene(ABS)polymer fuel to enhance hybrid rocket motor(HRM)performance through computational analysis,Chemical Equilibrium with Applications(CEA),software.ABS was selected as the base fuel due to its thermoplastic nature,which allows for the creation of complex fuel geometries through 3D printing,offering significant flexibility in fuel design.Hybrid rockets,which combine a solid fuel with a liquid oxidiser,offer advantages in terms of operational simplicity and safety.However,conventional polymer fuels often exhibit low regression rates and suboptimal combustion efficiencies.In this research,we evaluated a range of metal additives-aluminium(Al),boron(B),nickel(Ni),copper(Cu),and iron(Fe)-at chamber pressures ranging from 1 to 30 bar and oxidiser-to-fuel(O/F)ratios between 1.1 and 12,resulting in 1800 unique test conditions.The main performance parameters used to assess each formulation were characteristic velocity(C^(*))and adiabatic flame temperature.The results revealed that each test produced a different optimum O/F ratio,with most ratios falling between 4 and 6.The highest performance was achieved at a chamber pressure of 30 bar across all formulations.Among the additives,Al and B demonstrated significant potential for improved combustion performance with increasing metal loadings.In contrast,Fe,Cu,and Ni reached optimal performance at a minimum loading of 1%.Future work includes investigating B-Al metal composites as additives into the ABS base polymer fuel,and doing experimental validation tests where the metallised ABS polymer fuel is 3D printed.
基金Supported by Natural Science Foundation of China(30571086)
文摘Controlled release NPK compound fertilizers were prepared by means of in situ polymerization of monomers on the surface of fertilizer granules at room temperature. Methacrylate, α-methyl acrylic acid, and ethylene dimethylacrylate were used as monomers, Dibenzoyl peroxide as initiator, and cobalt naphthenate, and triethyl amine as promoters. The structures of coating materials were characterized by IR spectra. The thermogravimetric analysis result indicated that the coating materials were of good thermal stability. The mean thickness of single coating measured with screw gauge was ca. 140 μm. The morphologies of uncoated and coated fertilizer granules analyzed by using scanning electron microscopy were changed from porosities and gullies to hills and plain. The release rate of coated compound fertilizers in water could be controlled by the hydrophicity and thickness of coating. The increase in coating hydrophicity caused the increase in release rate of fertilizer. The increase in thickness of coating slowed the release rate.
文摘The core-shell 2,4,6,8,10,12-Hexanitro-2,4,6,8,10,12-hexaazaisowurtzitane/2,4,6-Trinitrotoluene(CL-20/TNT)composite was prepared by spray-drying method in which sensitive high energy explosive(CL-20)was coated with insensitive explosive(TNT).The structure and properties of different formulations of CL-20/TNT composite and CL-20/TNT mixture were characterized by scanning electron microscopy(SEM),Transmission electron microscopy(TEM),Laser particle size analyzer,X-ray photoelectron spectroscopy(XPS),X-ray diffraction(XRD),differential scanning calorimetry(DSC),impact sensitivity test and detonation performance.The results of SEM,TEM,XPS and XRD show that e-CL-20 particles are coated by TNT.When the ratio of CL-20/TNT is 75/25,core-shell structure is well formed,and thickness of the shell is about 20e30 nm.And the analysis of heat and impact show that with the increase of TNT content,the TNT coating on the core-shell composite material can not only catalyze the thermal decomposition of core material(CL-20),but also greatly reduce the impact sensitivity.Compared with the CL-20/TNT mixture(75/25)at the same ratio,the characteristic drop height of core-shell CL-20/TNT composite(75/25)increased by 47.6%and the TNT coating can accelerate the nuclear decomposition in the CL-20/TNT composites.Therefore,the preparation of the core-shell composites can be regarded as a unique means,by which the composites are characterized by controllable decomposition rate,high energy and excellent mechanical sensitivity and could be applied to propellants and other fields.
基金This work was supported by the National Natural Science Foundation of China(No.51571033,11804022)the Science and Technology on Transient Impact Laboratory Foundation(No.6142606183208).
文摘A facile and economical approach was developed for the large-scale production of powdered core-shell structured PTFE/Al (CS-PA) energetic materials through ultrasonic-assisted mixing. The low-cost micrometer-sized PTFE and Al particles were used as starting materials. Under high-power ultrasonic waves, the PTFE powder was dispersed into nano-to sub-micrometer-sized particles and then encapsulated the Al microparticles to form the core-shell structure. The heat of combustion, burning rate, and pressurization rate of the powdered CS-PA were measured. The thermal-initiated reaction behavior was further evaluated using thermogravimetry-differential scanning calorimetry. Subsequently, the bulk CS-PA with a uniform microstructure was obtained via cold isostatic pressing of the powdered CS-PA followed by vacuum sintering. For the bulk CS-PA, the quasi-static compression behavior was characterized, and the impact-initiated reaction processes were conducted using the Split Hopkinson Pressure Bar (SHPB) and evaluated by a high-speed camera. Compared to physically mixed PTFE/Al materials, the powdered and bulk CS-PA demonstrated enhanced thermal- and impact-initiated reaction characteristics respectively, proving the effectiveness of our approach for constructing core-shell structures.
基金financially supported by the National Natural Science Foundation of China (Grant NO.11702268)Sichuan provincial key S&T Special Projects (Grant NO.19DZX0106)
文摘Inspired by the phenomenon of superhydrophobic plants and animals in nature,1,3,5,7-tetranitro-1,3,5,7-tetrazocane(HMX)@copper stearate(CS)core-shell composites with similar properties was prepared.A rough shell layer on the surface of the HMX was observed by scanning electron microscopy(SEM),and a series of in-depth characterization confirmed the successful generation of CS and the coreshell structure of the samples.Differential scanning calorimeter(DSC)proves that the crystal transition temperature(204℃)and high temperature decomposition exothermal temperature(284℃)of HMX@CS is almost unchanged compared with pure HMX,which means HMX and CS have good compatibility.Then,the H50 of the samples also increased continuously(16.6 cm→33.7 cm)when the CS shell content increased from 1%to 5%,indicating that the CS shell has a certain buffering performance,and CS will absorb some heat and melt under the stimulation of impact due to its low melting point,which improved impact sensitivity of HMX effectively further.Moreover,HMX@CS has excellent hydrophobic and oleophilic performance,shows excellent wettability with lipid binder,and samples with appropriate CS shell content can continue to combustion stably after covering water.This waterproof and low sensitivity coating provides a new way for the development of multifunctional energetic materials.
基金the financial support by Postgraduate Research & Practice Innovation Program from Jiangsu Science and Technology Department under Grant number KYCX19_0320。
文摘Copper azide(CA), as a primary explosive with high energy density, has not been practically used so far because of its high electrostatic sensitivity. The Cu2O@HKUST-1 core-shell structure hybrid material was synthesized by the “bottle around ship” methodology in this research by regulating the dissolution rate of Cu2O and the generation rate of metal-organic framework(MOF) materials. Cu2O@HKUST-1 was carbonized to form a Cu O@porous carbon(CuO@PC) composite material. CuO@PC was synthesized into a copper azide(CA) @PC composite energetic material through a gas-solid phase in-situ azidation reaction.CA is encapsulated in PC framework, which acts as a nanoscale Faraday cage, and its excellent electrical conductivity prevents electrostatic charges from accumulating on the energetic material’s surface. The CA@PC composite energetic material has a CA content of 89.6%, and its electrostatic safety is nearly 30times that of pure CA(1.47 mJ compared to 0.05 mJ). CA@PC delivers an outstanding balance of safety and energy density compared to similar materials.
