Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structure...Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.展开更多
The desensitization of nitramine explosives while maintaining energetic performance is challenging.A highly efficient desensitizer is the key to solving the antinomy.This study focuses on using porous organic cages(PO...The desensitization of nitramine explosives while maintaining energetic performance is challenging.A highly efficient desensitizer is the key to solving the antinomy.This study focuses on using porous organic cages(POCs),specifically CC3 and RCC3,to desensitize RDX.By coating 0.1 wt%–5 wt%of POCs on RDX particles,a series of composite energetic materials were prepared.Characterization results show that POCs change the surface morphology of RDX,and there are interfacial interactions between them.The RDX@POCs composites exhibit enhanced stabilities in terms of heat,impact,friction,and electrostatic spark.For the RDX@RCC3-5%composite,the impact sensitivity(E_(IS)),friction sensitivity(E_(FS)),and electrostatic sensitivity(EES)were significantly reduced by 66.7%,68.8%,and 56.5%,respectively,while the detonation velocity decreased by merely 3.1%.These findings indicate that POCs,especially RCC3,are promising desensitizers for nitramine explosives,and their desensitization mechanisms likely involve barrier and buffering effects.The distinct desensitization behavior of RDX@RCC3 highlights the effectiveness of POCs in reducing the sensitivity of RDX without significantly compromising its energetic properties.展开更多
Nanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity gradients.Limited by less charge and weak ion selectivity of the raw material itself,ene...Nanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity gradients.Limited by less charge and weak ion selectivity of the raw material itself,energy conversion through nanofluidic channels is still facing considerable challenges.Here,a facile and efficient strategy to enhance osmotic energy harvesting based on drastically increasing surface charge density of MXenes subnanochannels via oxygen plasma is proposed.This plasma could break Ti–C bonds in the MXenes subnanochannels and effectively facilitate the formation of more Ti–O,C═O,O–OH,and rutile with a stronger negative charge and work function,which leads the surface potential of MXenes membrane to increase from 205 to 430 mV.This significant rise of surface charge endows the MXenes membrane with high cation selectivity,which could make the output power density of the MXenes membrane increase by 248.2%,reaching a high value of 5.92Wm^(−2) in the artificial sea‐river water system.Furthermore,with the assistance of low‐quality heat at 50℃,the osmotic power is enhanced to an ultrahigh value of 9.68Wm^(−2),which outperforms those of the state‐of‐the‐art two‐dimensional(2D)nanochannel membranes.This exciting breakthrough demonstrates the enormous potential of the facile plasma‐treated 2D membranes for osmotic energy harvesting.展开更多
The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate)(PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A(DGEBA) epoxy resin were investigated by i...The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate)(PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A(DGEBA) epoxy resin were investigated by impact test, tensile test and thermogravimetric analysis(TGA). The mechanism underlying the enhancement of mechanical properties of epoxy resin was studied using 1D wide-angle X-ray diffraction(WAXD) and scanning electron microscope(SEM). It was found that the mechanical properties of 1 wt%–5 wt% PDPVT/DGEBA composites were significantly improved compared to neat epoxy resin. Especially, the epoxy resin with 3 wt% PDPVT had the greatest increase in mechanical properties, with the impact strength, tensile strength and elongation while breaking increased by 87%, 59% and 174%, respectively. The increased mechanical strength was due to the fact that PDPVT maintained liquid crystalline phase in cured PDPVT/DGEBA composites, which would blunt the crack tip and prevent crack propagation. Moreover, PDPVT had slight effect on the thermal stability properties of epoxy resin.展开更多
Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base prop...Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose （NC） fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homoge- neous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 ℃, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO〉 CO, CO2, NH3, CH4, HCN, N2 CH20 and C2H40. The thermal decomposition process of the specimens was proposed.展开更多
With the development of nanotechnology,the precise synthesis of nanoparticles with nicely-defined dimensions and structures has been well-developed,and the functionalization and subsequent applications of the resultan...With the development of nanotechnology,the precise synthesis of nanoparticles with nicely-defined dimensions and structures has been well-developed,and the functionalization and subsequent applications of the resultant nanostructures are becoming increas-ingly important.Comparing to inorganic nanoparticles,the nanostructures based on soft matters,especially block copolymer as-semblies,are much lower in cost,easier to fabricate and richer in morphology.However,the dimensional control over the block co-polymer assemblies is not as easy.Only in recent decade,with the discovery of living Crystallization-Driven Self-Assembly(CDSA)by Manners and Winnik,researchers become able to precisely tune the sizes of block copolymer assemblies in a relatively wide range.This discovery has inspired tremendous research effort in the self-assembly field,and considerable progress has been made recently.This review summarizes the main progress in the precise and controllable self-assembly field in the past five years,and is mostly fo-cused on four aspects,including in-depth understanding of the assembly methods,extension of this method to two-dimensional nanostructures,utilization of this method to fabricate hierarchical structures,and the potential applications of these well-defined nanostructures.We hope not only to make a periodic systematic summary of previous studies,but also to provide some useful thinking for the future development of this field.展开更多
Polymersomes,nanoscopic polymer vesicles self-assembled from synthetic block copolymers,are ideal candidates for drug delivery and synthetic biology,due to their characteristic of high stability,chemical
基金Fundamental Research Funds for the Central Universities,Grant/Award Number:3052017010。
文摘Inhibiting the agglomeration of molten aluminum particles packed in the binder network is a promising scheme to achieve efficient combustion of solid propellants.In this investigation,the hydroxyl-terminated structured fluorinated alcohol compound(PFD)was introduced to modify the traditional polyethylene glycol/polytetrahydrofuran block copolymerization(HTPE)binder;that is,a unique fluorinated polyether(FTPE)binder was synthesized by embedding fluorinated organic segments into the HTPE binder via crosslinking curing.The FTPE was applied in aluminum-based propellants for the first time.Due to the complete release of fluorinated organic active segments in the range of 300℃to 400℃,the burning rate of FTPEbased propellant increased from 4.07(0%PFD)to 6.36 mm/s(5%PFD),increased by 56.27%under 1 MPa.The reaction heat of FTPE propellants increased from 5.95(0%PFD)to 7.18 MJ/kg(5%PFD)under 3.0 MPa,indicating that HTPE binder modified with PFD would be conducive to inhibiting the D90 of condensed combustion products(CCPs)dropped by 81.84%from 75.46(0%PFD)to 13.71μm(5%PFD)under 3.0 MPa,in consistent with the significant reduction of aluminum agglomerates observed on the quenched burning surface of the propellants.Those results demonstrated that a novel FTPE binder with PFD can release fluorinated organic active segments,which motivate preignition reaction with the alumina shell in the early stage of aluminum combustion,and then enhance the melting diffusion effect of aluminum to inhibit the agglomeration.
文摘The desensitization of nitramine explosives while maintaining energetic performance is challenging.A highly efficient desensitizer is the key to solving the antinomy.This study focuses on using porous organic cages(POCs),specifically CC3 and RCC3,to desensitize RDX.By coating 0.1 wt%–5 wt%of POCs on RDX particles,a series of composite energetic materials were prepared.Characterization results show that POCs change the surface morphology of RDX,and there are interfacial interactions between them.The RDX@POCs composites exhibit enhanced stabilities in terms of heat,impact,friction,and electrostatic spark.For the RDX@RCC3-5%composite,the impact sensitivity(E_(IS)),friction sensitivity(E_(FS)),and electrostatic sensitivity(EES)were significantly reduced by 66.7%,68.8%,and 56.5%,respectively,while the detonation velocity decreased by merely 3.1%.These findings indicate that POCs,especially RCC3,are promising desensitizers for nitramine explosives,and their desensitization mechanisms likely involve barrier and buffering effects.The distinct desensitization behavior of RDX@RCC3 highlights the effectiveness of POCs in reducing the sensitivity of RDX without significantly compromising its energetic properties.
基金National Natural Science Foundation of China,Grant/Award Number:52175174China Postdoctoral Science Foundation,Grant/Award Number:2022M721791National Key Research and Development Program of China,Grant/Award Number:2020YFA0711003。
文摘Nanofluidic channels inspired by electric eels open a new era of efficient harvesting of clean blue osmotic energy from salinity gradients.Limited by less charge and weak ion selectivity of the raw material itself,energy conversion through nanofluidic channels is still facing considerable challenges.Here,a facile and efficient strategy to enhance osmotic energy harvesting based on drastically increasing surface charge density of MXenes subnanochannels via oxygen plasma is proposed.This plasma could break Ti–C bonds in the MXenes subnanochannels and effectively facilitate the formation of more Ti–O,C═O,O–OH,and rutile with a stronger negative charge and work function,which leads the surface potential of MXenes membrane to increase from 205 to 430 mV.This significant rise of surface charge endows the MXenes membrane with high cation selectivity,which could make the output power density of the MXenes membrane increase by 248.2%,reaching a high value of 5.92Wm^(−2) in the artificial sea‐river water system.Furthermore,with the assistance of low‐quality heat at 50℃,the osmotic power is enhanced to an ultrahigh value of 9.68Wm^(−2),which outperforms those of the state‐of‐the‐art two‐dimensional(2D)nanochannel membranes.This exciting breakthrough demonstrates the enormous potential of the facile plasma‐treated 2D membranes for osmotic energy harvesting.
基金financially supported by the National Natural Science Foundation of China(51343008)
文摘The effects of mesogen-jacketed liquid crystalline polymer poly(dipropyl vinylterephthalate)(PDPVT) on the mechanical and thermal properties of diglycidyl ether of bisphenol-A(DGEBA) epoxy resin were investigated by impact test, tensile test and thermogravimetric analysis(TGA). The mechanism underlying the enhancement of mechanical properties of epoxy resin was studied using 1D wide-angle X-ray diffraction(WAXD) and scanning electron microscope(SEM). It was found that the mechanical properties of 1 wt%–5 wt% PDPVT/DGEBA composites were significantly improved compared to neat epoxy resin. Especially, the epoxy resin with 3 wt% PDPVT had the greatest increase in mechanical properties, with the impact strength, tensile strength and elongation while breaking increased by 87%, 59% and 174%, respectively. The increased mechanical strength was due to the fact that PDPVT maintained liquid crystalline phase in cured PDPVT/DGEBA composites, which would blunt the crack tip and prevent crack propagation. Moreover, PDPVT had slight effect on the thermal stability properties of epoxy resin.
文摘Glycidyl azide polymer （GAP） with the advantages of non-volatility and excellent thermal stability is a candidate as a re- placement for nitroglycerine （NG） in a double base propellant. The GAP-NC double base propellants were formulated with GAP and nitrocellulose （NC） fibers. Tensile test and SEM characterization indicated that GAP-NC propellants had a homoge- neous structure. Thermogravimetric analysis of GAP-NC propellants revealed that the onset decomposition temperature reached a high level ranging from 192.9 to 194.6 ℃, which indicated that the substitution of NG with GAP contributed to the safe storage and process operations for double base propellant. The result analysis of decomposition products of GAP-NC propellants showed that the main gas decomposition products of the propellants were NO, NO〉 CO, CO2, NH3, CH4, HCN, N2 CH20 and C2H40. The thermal decomposition process of the specimens was proposed.
基金supported by the National Natural Science Foundation of China(Nos.51973019 and 22175024)B.X.is grateful to the fellow ship of China Postdoctoral Science Foundation(No.2021TQ0033).
文摘With the development of nanotechnology,the precise synthesis of nanoparticles with nicely-defined dimensions and structures has been well-developed,and the functionalization and subsequent applications of the resultant nanostructures are becoming increas-ingly important.Comparing to inorganic nanoparticles,the nanostructures based on soft matters,especially block copolymer as-semblies,are much lower in cost,easier to fabricate and richer in morphology.However,the dimensional control over the block co-polymer assemblies is not as easy.Only in recent decade,with the discovery of living Crystallization-Driven Self-Assembly(CDSA)by Manners and Winnik,researchers become able to precisely tune the sizes of block copolymer assemblies in a relatively wide range.This discovery has inspired tremendous research effort in the self-assembly field,and considerable progress has been made recently.This review summarizes the main progress in the precise and controllable self-assembly field in the past five years,and is mostly fo-cused on four aspects,including in-depth understanding of the assembly methods,extension of this method to two-dimensional nanostructures,utilization of this method to fabricate hierarchical structures,and the potential applications of these well-defined nanostructures.We hope not only to make a periodic systematic summary of previous studies,but also to provide some useful thinking for the future development of this field.
文摘Polymersomes,nanoscopic polymer vesicles self-assembled from synthetic block copolymers,are ideal candidates for drug delivery and synthetic biology,due to their characteristic of high stability,chemical
