高峰 , 张泽 . 含装药缺陷的固体火箭发动机性能评估综述 [J ] . 兵工学报 , 2021 , 42 ( 8 ): 1789 - 1802 .

GAO F , ZHANG Z . Review on performance evaluation of solid rocket motors with charge defects [J ] . Acta Armamentarii , 2021 , 42 ( 8 ): 1789 - 1802 . (in Chinese) DOI: 10.3969/j.issn.1000-1093.2021.08.024 http://doi.org/10.3969/j.issn.1000-1093.2021.08.024 The charge defect is an important factor affecting the safe work of solid rocket motors (SRM). In order to ensure safe launch, the deviation of the SRM performance caused by the charge defects needs to be analyzed to evaluate the working performance of SRM. In view of the complexity of the behavior of charge defects, a complete evaluation system has not been established. For the behavior of SRM charge defects, the theoretical and experimental research methods of crack and debonding propagation are reviewed, including the research on the crack initiation criterion, the factors affecting the growth and the fracture performance of propellant material. The research status of the interaction mechanism between grain crack and gas is reviewed from two aspects: the boundary conditions of gas entering the crack and the influence of gas propagation on the crack propagation. In order to achieve the purpose of numerical simulation of complete working process of SRM with charge defects, the research on its numerical calculation methods is summarized and analyzed from combustion surface regression calculation method, fluid-heat-solid coupling calculation method and defect propagation calculation method. The numerical index of the working performance of SRM with charge defects is expected to be obtained, which will be used as a reference for performance evaluation of SRM with charge defects. Finally, the development in the research on the behavior of charge defects and numerical calculation methods is prospected.

MAHDAVI M , FARROKHPOUR H , TAHRIRI M . Investigation of simultaneous formation of nano-sized CuO and ZnO on the thermal decomposition of ammonium perchlorate for composite solid propellants [J ] . Journal of Thermal Analysis & Calorimetry , 2018 , 132 ( 2 ): 879 - 893 .

ARISAWA H , BRILL T B . Flash pyrolysis of hydroxyl-terminated polybutadiene(HTPB) Ⅱ: implications of the kinetics to combustion of organic polymers [J ] . Combustion and Flame , 1996 , 106 ( 1/2 ): 144 - 154 .

JAIN S , GUPTA G , KSHIRSAGAR D R , et al. Burning rate and other characteristics of strontium titanate(SrTiO 3 ) supplemented AP/HTPB/Al composite propellants-ScienceDirect [J ] . Defence Technology , 2019 , 15 ( 3 ): 313 - 318 .

PANG W Q , LI Y , DELUCA L T , et al. Effect of metal nanopowders on the performance of solid rocket propellants:a review [J ] . Nanomaterials , 2021 , 11 ( 10 ): 2749 - 2774 .

AO W , FAN Z M , LIU L , et al. Agglomeration and combustion characteristics of solid composite propellants containing aluminum-based alloys [J ] . Combustion and Flame , 2020 , 220 ( 10 ): 288 - 297 .

VELLAISAMY U , BISWAS S . Effect of metal additives on neutralization and characteristics of AP/HTPB solid propellants [J ] . Combustion and Flame , 2020 , 221 ( 11 ): 326 - 337 .

TU C Y , CHEN X , LI Y K , et al. Experimental study of Al agglomeration on solid propellant burning surface and condensed combustion products [J ] . Defence Technology , 2023 , 26 : 111 - 122 .

YUAN J F , LIU J Z , ZHOU Y N , et al. Aluminum agglomeration of AP/HTPB composite propellant [J ] . Acta Astronautica , 2019 , 156 ( 3 ): 14 - 22 .

WANG D Q , CAO X F , LIU J , et al. TF-Al/TiC highly reactive composite particle for application potential in solid propellants [J ] . Chemical Engineering Journal , 2021 , 425 ( 12 ): 130674 .

EMELYANOV V N , TETERINA I V , VOLKOV K N . Dynamics and combustion of single aluminium agglomerate in solid propellant environment-ScienceDirect [J ] . Acta Astronautica , 2020 , 176 ( 11 ): 682 - 694 .

HAN L , LI J W , WANG Y B , et al. Study on combustion oscillation characteristics of micron aluminum particles [J ] . Powder Technology , 2021 , 394 ( 12 ): 782 - 790 .

ISERT S , LANE C D , GUNDUZ I E , et al. Tailoring burning rates using reactive wires in composite solid rocket propellants [J ] . Proceedings of the Combustion Institute , 2017 , 36 ( 2 ): 2283 - 2290 .

JIANG Z , LI S F , LI K , et al. Laser ignition and combustion properties of composite propellant containing nanometal powders [J ] . AIAA Journal , 2006 , 44 ( 7 ): 1463 - 1467 .

ARMSTRONG R W , BASCHUNG B , BOOTH D W , et al. Enhanced propellant combustion with nanoparticles [J ] . Nano Letters , 2003 , 3 ( 2 ): 253 - 255 .

ISERT S , GROVEN L J , LUCHT R P , et al. The effect of encapsulated nanosized catalysts on the combustion of composite solid propellants [J ] . Combustion and Flame , 2015 , 162 ( 5 ): 1821 - 1828 .

CHENG Z P , CHU X Z , YIN J Z , et al. Formation of composite fuels by coating aluminum powder with a cobalt nanocatalyst:enhanced heat release and catalytic performance [J ] . Chemical Engineering Journal , 2020 , 385 : 123859 .

KIM D W , KIM K T , LEE D U , et al. Synergetic enhancement in the reactivity and stability of surface-oxide-free fine Al particles covered with a polytetrafluoroethylene nanolayer [J ] . Scientific Reports , 2020 , 10 ( 1 ): 14560 . DOI: 10.1038/s41598-020-71162-z http://doi.org/10.1038/s41598-020-71162-z Surface oxide (AlO) of reactive fine aluminum (Al) particles for solid fuels, propellants, and brazing materials often restricted oxidative performance, though the passivation film acts to protect Al particles from exploding. Here, we report fine Al particles fully covered with a polytetrafluoroethylene (PTFE) layer instead of an AlO film on the surface. This advance is based on the introduction of strong Al-F bonds, known to be an alternative to the Al-O bonds of surface oxides. The DSC results on the PTFE-coated Al particles exhibit higher reactive-exothermic enthalpy energy (12.26 kJ g) than 4.85 kJ g by uncoated Al particles. The artificial aging test of the PTFE layer on the Al particles show long-time stability to the external circumstance compared to those by AlO. The activation energy for oxidation was investigated from cyclic voltammetry assessment and the measured peak potentials of the anode curve for PTFE/Al (- 0.45 V) and uncoated Al (- 0.39 V) are achieved, respectively. This means that the PTFE layer is more stable against a sudden explosion of Al particles compared to AlO. These results are very useful given its capability to control both the reactivity and stability levels during the oxidation of Al particles for practical applications.

YE M Q , ZHANG S T , LIU S S , et al. Preparation and characterization of pyrotechnics binder-coated nano-aluminum composite particles [J ] . Journal of Energetic Materials , 2016 , 35 ( 3 ): 300 - 313 .

XIAO L Q , PANG W Q , QIN Z , et al. Cluster analysis of Al agglomeration in solid propellant combustion [J ] . Combustion and Flame , 2019 , 203 : 386 - 396 . DOI: 10.1016/j.combustflame.2018.12.032 http://doi.org/10.1016/j.combustflame.2018.12.032 The pocket concept describes aluminum-rich structure bounded by oxidizer particles in a solid propellant. Al particles inside a pocket tend to coalesce into a single agglomerate at the burning surface. However, detecting Al-rich microstructures in a real propellant is a challenging task. A calculation model based on cluster analysis and 3D model propellants is proposed to identify the Al-rich clusters and estimate the size distribution of the Al agglomerates. The effects of the parameters and propellant structures on the calculations were studied. The model was validated by comparing the modeled results with existing experimental data. The results demonstrate that the cluster structure of different hierarchies can be obtained by adjusting the user-prescribed parameters according to the reachability-plot. The present method is able to simulate the effect of the propellant microstructure on the Al-rich regions. In addition, the agglomerates of an HTPB (Hydroxyl-terminated polybutadiene) propellant is investigated under 1 MPa. The estimated size distribution of the agglomerates matches well with the experimental results. (C) 2019 The Combustion Institute. Published by Elsevier Inc.

XIAO L Q , FAN X Z , LI J Z , et al. Effect of Al content and particle size on the combustion of HMX-CMDB propellant [J ] . Combustion and Flame , 2020 , 214 : 80 - 89 .

TEJASVI K , VENKATESHWARA RAO V , PYDISETTY Y , et al. Studies on aluminum agglomeration and combustion in catalyzed composite propellants [J ] . Combustion, Explosion, and Shock Waves , 2021 , 57 ( 2 ): 203 - 214 .

WANG W M , LI H , YANG Y J , et al. Enhanced thermal decomposition, laser ignition and combustion properties of NC/Al/RDX composite fibers fabricated by electrospinning [J ] . Cellulose , 2021 , 28 ( 10 ): 6089 - 6105 .

MUTLU M , KANG J H , RAZA S , et al. Thermoplasmonic ignition of metal nanoparticles [J ] . Nano Letters , 2018 , 18 ( 3 ): 1699 - 1706 . DOI: 10.1021/acs.nanolett.7b04739 http://doi.org/10.1021/acs.nanolett.7b04739 Explosives, propellants, and pyrotechnics are energetic materials that can store and quickly release tremendous amounts of chemical energy. Aluminum (Al) is a particularly important fuel in many applications because of its high energy density, which can be released in a highly exothermic oxidation process. The diffusive oxidation mechanism (DOM) and melt-dispersion mechanism (MDM) explain the ways powders of Al nanoparticles (NPs) can burn, but little is known about the possible use of plasmonic resonances in NPs to manipulate photoignition. This is complicated by the inhomogeneous nature of powders and very fast heating and burning rates. Here, we generate Al NPs with well-defined sizes, shapes, and spacings by electron beam lithography and demonstrate that their plasmonic resonances can be exploited to heat and ignite them with a laser. By combining simulations with thermal-emission, electron-, and optical-microscopy studies, we reveal how an improved control over NP ignition can be attained.

WANG F Y , WU Z G , SHANGGUAN X H , et al. Preparation of mono-dispersed, high energy release, core/shell structure Al nanopowders and their application in HTPB propellant as combustion enhancers [J ] . Scientific Reports , 2017 , 7 : 5228 . DOI: 10.1038/s41598-017-05599-0 http://doi.org/10.1038/s41598-017-05599-0 Mono-dispersed, spherical and core/ shell structure aluminum nanopowders (ANPs) were produced massively by high energy ion beam evaporation (HEIBE). And the number weighted average particle size of the ANPs is 98.9 nm, with an alumina shell (3-5 nm). Benefiting from the passivation treatment, the friction, impact and electrostatic spark sensitivity of the ANPs are almost equivalent to those of aluminum micro powders. The result of TG-DSC indicates the active aluminum content of ANPs is 87.14%, the enthalpy release value is 20.37 kJ/g, the specific heat release S-1/Delta m(1)* (392-611 degrees C) which determined the ability of energy release is 19.95 kJ/g. And the value of S-1/Delta m(1)* is the highest compared with ANPs produced by other physical methods. Besides, the ANPs perfectly compatible with hydroxylterminated polybutadiene (HTPB), 3 wt. % of ANPs were used in HTPB propellant replaced micron aluminum powders, and improved the burning rate in the 3-12 MPa pressure range and reduced the pressure exponential by more than 31% in the 3-16 MPa pressure range. The production technology of ANPs with excellent properties will greatly promote the application of ANPs in the field of energetic materials such as propellant, explosive and pyrotechnics.

XIAO L , ZHAO L J , KE X , et al. Energetic metastable Al/CuO/PVDF/RDX microspheres with enhanced combustion performance-ScienceDirect [J ] . Chemical Engineering Science , 2020 , 231 : 116302 .

BALBUDHE K , ROY A , CHAKRAVARTHY S R . Computer modelling of nano-aluminium agglomeration during the combustion of composite solid propellants [J ] . Proceedings of the Combustion Institute , 2015 , 35 ( 2 ): 2471 - 2478 .

LIU J P , ZHANG H R , YAN Q L . Anti-sintering behavior and combustion process of aluminum nano particles coated with PTFE:a molecular dynamics study [J ] . Defence Technology , 2023 , 24 : 46 - 57 .

LIU Y Z , CHEN J , LIU J G , et al. Core-shell structure mediated microstructure and mechanical properties of high entropy alloy CoCrFeNi/Al composites [J ] . Vacuum , 2021 , 192 : 110454 .

BOCANEGRA P E , CHAUVEAU C , GÖKALP I . Experimental studies on the burning of coated and uncoated micro and nano-sized aluminium particles [J ] . Aerospace Science and Technology , 2007 , 11 ( 1 ): 33 - 38 .

王慧心 , 任慧 , 闫涛 , 等 . 聚乙烯醇原位包覆铝粉结构表征及活性铝含量测定 [J ] . 兵工学报 , 2019 , 40 ( 7 ): 1373 - 1380 . DOI: 10.3969/j.issn.1000-1093.2019.07.006 http://doi.org/10.3969/j.issn.1000-1093.2019.07.006 针对氧化铝外壳导致纳米铝粉反应活性下降的问题，尝试在电爆炸制备纳米铝粉的同时直接用聚乙烯醇(PVA)包覆。利用扫描电镜、透射电镜、动态光散射激光粒度仪、X射线光电子能谱仪及同步热分析仪表征样品的表观形貌、粒度分布，表面元素价态以及热响应行为。依据有色金属行业标准YS/T 617.1—2007，分别对微米铝粉、纳米铝粉及原位包覆产物的燃烧热和活性铝含量进行测定。研究结果表明：PVA原位包覆铝粉具有多核结构，球形度良好；包覆样品活性铝含量达到84.27%，比纳米铝粉提高了22%，PVA包覆有效降低了氧化铝外壳的生长厚度；与微米铝粉相比，包覆样品氧化反应起始温度低（548.6 ℃），释能迅速；PVA原位包覆铝粉兼具高反应活性和快速释能效应，在含能材料中具有潜在的应用优势。

WANG H X , REN H , YAN T , et al. Micro-structure and active aluminum content of aluminum powder in situ coated by polyvinyl Alcohol [J ] . Acta Armamentarii , 2019 , 40 ( 7 ): 1373 - 1380 . (in Chinese) DOI: 10.3969/j.issn.1000-1093.2019.07.006 http://doi.org/10.3969/j.issn.1000-1093.2019.07.006 In order to solve the decrease in the reactivity of nano-aluminum powder due to the alumina shell on its surface, the nano-aluminum powders were directly encapsulated by polyvinyl alcohol (PVA) during electrical explosion of wires. The apparent morphology of sample was detected by scanning electron microscope (SEM) and transmission electron microscope (TEM), and the particle size distribution was characterized by dynamic laser light scattering particle size analyzer. The valence states of surface elements were analyzed by X-ray photoelectron spectroscope, and the thermal behaviours of micrometer Al, nanometer Al and products were compared by simultaneous thermal analyzer. The combustion heat was measured according to relevant national military standards, and active Al content was measured using NaOH exhaust method. The results show that the average size of coated sample is nearly 200 nm, and the particles form a multi-core structure. The active Al content reaches 84.27% which is 22% higher than that of ordinary nano-Al particles. It was proved that PVA effectively relieves oxidation of nano-Al. The coated products have low onset temperature of oxidation (548.6 ℃) and can release energy more rapidly compared to micro-Al. The in-situ coated sub-micro Al has high active reactivity and quick energy release rate. Key

闫涛 , 任慧 , 马爱娥 , 等 . 氟橡胶包覆层对纳米铝粉性能的影响研究 [J ] . 兵工学报 , 2019 , 40 ( 8 ): 1611 - 1617 . DOI: 10.3969/j.issn.1000-1093.2019.08.008 http://doi.org/10.3969/j.issn.1000-1093.2019.08.008 氟橡胶包覆改性纳米铝粉是近年来含能材料领域的研究热点。为了获得包覆层对纳米铝粉性能的影响规律，将电爆法制备的铝粉包覆5%、10%、15%3种不同含量的氟橡胶，并引入钝化纳米铝粉进行对比研究。利用扫描电镜、透射电镜、物理吸附分析仪、X射线光电子能谱仪及同步热分析仪表征改性前后纳米铝粉的表观形貌、包覆层厚度、比表面积、表面元素价态以及热响应行为，测定活性铝含量和燃烧热。结果表明：改性纳米铝粉形貌规整、粒径分布均匀，比表面积略高于钝化纳米铝粉；氟橡胶包覆层通过化学键吸附在铝粉表面，增强了纳米铝粉的热稳定性，阻止了纳米铝粉的进一步氧化，使其活性铝含量高于自然失活的纳米铝粉，最高达到85.85%；受氟橡胶包覆层的影响，改性纳米铝粉的燃烧热高于钝化纳米铝粉。

YAN T , REN H , MA A E , et al. Effect of fluorine rubber coating on properties of nano-aluminum powder [J ] . Acta Armamentarii , 2019 , 40 ( 8 ): 1611 - 1617 . (in Chinese) DOI: 10.3969/j.issn.1000-1093.2019.08.008 http://doi.org/10.3969/j.issn.1000-1093.2019.08.008 In order to obtain the influence of coating layers on the properties of nano-aluminum powders, the nano-aluminum powders prepared by the electric explosion method are coated with 5%, 10% and 15% of fluororubber. The surface morphologies, coating thicknesses, specific surface areas, elemental valence states and thermal responses of modified nano-aluminum powders are characterized using scanning electron microscope, transmission electron microscope, physical adsorption analyzer, X-ray photoelectron spectrometer and simultaneous thermal analyzer. And the active aluminum contents and combustion heat of different samples were measured. The results show that the specific surface areas of the modified nano-aluminum powders are slightly large than that of the passivated nano-aluminum powders. Fluororubber coatings chemically adsorb on the surface of nano-aluminum powders, which enhances the thermal stability of nano-aluminum powders, prevents the aluminum powders from further oxidation, and makes one of the contents of active aluminum up to 85.85%. The fluororubber promotes the combustion of modified nano-aluminum powders, so that the combustion heat of the modified nano-aluminum powders is more than that of the passivated nano-aluminum powders. Key

GAO F , XU C , ZHANG H P , et al. Core-shell structured al-matrix composite with enhanced mechanical properties [J ] . Materials Science & Engineering A , 2016 , 657 : 64 - 70 .

HUANG S D , PAN M , DENG S L , et al. Modified micro-emulsion synthesis of highly dispersed Al/PVDF composites with enhanced combustion properties [J ] . Advanced Engineering Materials , 2019 , 21 ( 5 ): 1801330.

KHELIFA F , ERSHOV S , DRUART M E , et al. A multilayer coating with optimized properties for corrosion protection of Al [J ] . Journal of Materials Chemistry A , 2015 , 3 ( 31 ): 15977 - 15985 .

NIE H , PISHARATH S , HNG H H . Combustion of fluoropolymer coated Al and Al-Mg alloy powders [J ] . Combustion and Flame , 2020 , 220 : 394 - 406 .

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ZHANG M Y , BIESOLD G M , CHOI W , et al. Recent advances in polymers and polymer composites for food packaging [J ] . Materials Today , 2022 , 53 : 134 - 161 .

GOMANN I , HALBACH M , SCHOLZ-BTTCHER B M . Car and truck tire wear particles in complex environmental samples-a quantitative comparison with “traditional” microplastic polymer mass loads-ScienceDirect [J ] . Science of the Total Environment , 2021 , 773 : 145667 .

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HSISSOU R , SEGHIRI R , BENZEKRI Z , et al. Polymer composite materials:a comprehensive review [J ] . Composite Structures , 2021 , 262 : 113640 .

WANG J , QIAO Z Q , YANG Y T , et al. Core-shell Al-polytetrafluoroethylene(PTFE) configurations to enhance reaction kinetics and energy performance for nanoenergetic materials [J ] . Chemistry-A European Journal , 2016 , 22 ( 1 ) 279 - 284 .

WANG J , ZENG C C , ZHAN C H , et al. Tuning the reactivity and combustion characteristics of PTFE/Al through carbon nanotubes and grapheme [J ] . Thermochimica Acta , 2019 , 676 : 276 - 281 .

ZHAO B B , SUN S X , LUO Y J , et al. Fabrication of polytetrafluoroethylene coated micron aluminium with enhanced oxidation [J ] . Materials , 2020 , 13 ( 15 ): 3384.

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XIAO F , YANG R J , LI J M . Preparation and characterization of mechanically activated aluminum/polytetrafluoroethylene composites and their reaction properties in high temperature water steam [J ] . Journal of Alloys and Compounds , 2018 , 761 : 24 - 30 .

XIAO F , LIANG T X . Preparation of hierarchical core-shell Al-PTFE@TA and Al-PTFE@TA-Fe architecture for improving the combustion and ignition properties of aluminum [J ] . Surface and Coatings Technology , 2021 , 412 : 127073 .

MAO Y F , HE Q Q , WANG J , et al. Tuning energy output of PTFE/Al composite materials through gradient structure [J ] . Defence Technology , 2022 .DOI: 10.1016/j.dt.2022.05.015 https://dx.doi.org/10.1016/j.dt.2022.05.015 .

WU Z Y , LIU J X , ZHANG S , et al. Enhanced thermal- and impact-initiated reactions of PTFE/Al energetic materials through ultrasonic-assisted core-shell construction [J ] . Defence Technology , 2021 , 18 ( 8 ): 1362 - 1368 .

DONG W K , KIM K T , LEE D U , et al. Influence of poly(vinylidene fluoride) coating layer on exothermic reactivity and stability of fine aluminum particles [J ] . Applied Surface Science , 2021 , 551 : 149431 .

KIM D W , KIM K T , MIN T S , et al. Improved energetic-behaviors of spontaneously surface-mediated Al particles [J ] . Scientific Reports , 2017 , 7 ( 1 ): 4659 . DOI: 10.1038/s41598-017-04758-7 http://doi.org/10.1038/s41598-017-04758-7 Surface-mediated Al particles are synthesized by incorporating the stable fluoride reaction of Al-F on a pure Al surface in place of natural oxides. Al particles with fluoro-polymer directly adsorbed on the surface show a considerable capability to overcome limitations caused by the surface oxide. Here, we report that Al fluoride when spontaneously formed at the poly(vinylidene fluoride)/Al interface serves as an oxidation-protecting layer while also providing an efficient combustion path along which the internal Al rapidly reacts with external oxygen atoms. Both thermal oxidation and explosion tests of the poly(vinylidene fluoride)/Al particles show superior exothermic enthalpy energy and simultaneously rapid oxidation reactivity compared to those of AlO passivated Al particles. It is clearly elucidated that the enhanced energetic properties of Al particles mediated by poly(vinylidene fluoride) originate from the extraordinary pyrolytic process of Al fluoride occurring at a low temperature compared to AlO passivated Al. Hence, these results clarify that the surface mediation of Al particles can be significantly considered as advanced technology for many energetic applications.

DELISIO J B , HU X L , WU T , et al. Probing the reaction mechanism of aluminum/fluoropolymer composites [J ] . Journal of Physical Chemistry B , 2016 , 120 ( 24 ): 5534 - 5542 .

MAO Y F , HE Q Q , WANG J , et al. Rational design of gradient structured fluorocarbon/Al composites towards tunable combustion performance [J ] . Combustion and Flame , 2021 , 230 : 111436 .

YANG H T , HUANG C , CHEN H H . Tuning reactivity of nanoaluminum with fluoropolymer via electrospray deposition [J ] . Journal of Thermal Analysis & Calorimetry , 2017 , 127 ( 3 ): 2293 - 2299 .

WANG H Y , KLINE D J , REHWOLDT M , et al. Architecture can significantly alter the energy release rate from nanocomposite Energetics [J ] . ACS Applied Polymer Materials , 2019 , 1 ( 5 ): 982 - 989 .

CHEN S H , YU H S , ZHANG W , et al. Sponge-like Al/PVDF films with laser sensitivity and high combustion performance prepared by rapid phase inversion [J ] . Chemical Engineering Journal , 2020 , 396 : 124962 .

VITALE A , QUAGLIO M , MARASSO S L , et al. Direct photolithography of perfluoropolyethers for solvent-resistant microfluidics [J ] . Langmuir , 2013 , 29 ( 50 ): 15711 - 15718 . DOI: 10.1021/la402755q http://doi.org/10.1021/la402755q In this work, photocurable perfluoropolyethers (PFPEs) have been used for the fabrication of microfluidic devices by a direct photolithographic process. During this mask-assisted photopolymerization technique, the material is directly photopolymerized in the presence of a mask, avoiding the use of a master. We demonstrate the high level of control in transferring micropattern features with high density, a minimum transferred size of 15 μm, a high aspect ratio (at least up to 6.5), and complex shapes useful for microfluidic applications. Moreover, we successfully apply this technology to fabricate sealed devices; the fabrication time scale for the overall process is around 5 min. The devices are able to withstand a flow pressure of up to 3.8 bar, as required for most microfluidics. Finally, the devices are tested with a model reaction employing organic solvents.

MILLER H A , KUSEL B S , DANIELSON S T , et al. Metastable nanostructured metallized fluoropolymer composites for energetics [J ] . Journal of Materials Chemistry , 2013 , 1 ( 24 ): 7050 - 7058 .

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TANG W , YANG R J , ZENG T , et al. Positive effects of organic fluoride on reduction of slag accumulation in static testing of solid rocket motors of different diameters [J ] . Acta Astronautica , 2022 , 194 : 277 - 285 .

KE X , GUO S F F , GUO B W , et al. Superhydrophobic fluorine-containing protective coating to endow Al nanoparticles with long-term storage stability and self-activation reaction capability [J ] . Advanced Materials Interfaces , 2019 , 6 ( 19 ): 1901025 - 1901036 .

ZHANG L C , WANG S , SU X , et al. Preparation and characterization of core-shell Al@PFHP with improving the combustion and ignition properties of aluminum powder [J ] . Particuology , 2022 , 77 : 62 - 70 .

COHEN O , MICHAELS D , YAVOR Y . Agglomeration in composite propellants containing different nano-aluminum powders [J ] . Propellants, Explosives, Pyrotechnics , 2022 , 47 ( 9 ):e202100320.

JIAO Y K , LI S G , LI G P , et al. Effect of fluoropolymer content on thermal and combustion performance of direct writing high-solid nanothermite composite [J ] . RSC Advances , 2022 , 12 ( 9 ): 5612 - 5618 . DOI: 10.1039/d1ra08970f http://doi.org/10.1039/d1ra08970f The addition of fluoropolymers can improve the reactivity of Al and enhance the combustion performance of thermites, which has attracted great interest. Also, direct writing 3D printing technology for the preparation of energetic materials is an innovative process that can meet a variety of complex requirements. In this study, soluble Viton F2311 was used as a binder, and F2311/Al/CuO (FMICs) nanocomposites were prepared by direct writing. The components of FMICs were evenly distributed without obvious agglomeration. The thermal and combustion properties of FMICs with different mass fractions of F2311 were systematically studied. As the F2311 content increases, the thermite reaction of FMICs is advanced and the system has a higher exothermic and combustion rate. The F2311 content had little effect on the combustion flame temperature of FMICs, all of which were above 2400 K. Compared with PTFE and new fluoropolymers/nanothermites, F2311/nanothermites shows better processability and reaction properties and probably has promising applications.This journal is © The Royal Society of Chemistry.

WANG H X , REN H , YAN T Y , et al. A latent highly activity energetic fuel: thermal stability and interfacial reaction kinetics of selected fluoropolymer encapsulated sub-micron sized Al particles [J ] . Scientific Reports , 2021 , 11 ( 1 ): 738 - 751 . DOI: 10.1038/s41598-020-80865-2 http://doi.org/10.1038/s41598-020-80865-2 Aluminum can enhance heat release of energetic composite in theory. However, the commonly used micron aluminum powder has several short comings like incomplete reaction and low reaction rate. Meanwhile, outer oxide shell of nano Al particle is thicker than micro Al, which leads to low active aluminum content and insufficient heat release. On the basis of previous research, reported fluoropolymers modified Al particles were compared and suitable F2311was chosen. Sub-micron scale Al (median particle size around 200 nm) was regarded as optimum coated object in consideration of activity content of aluminum powder changing with particle size. The super fine Al powder was prepared by electrical explosion method, and encapsulated in situ by selected fluorine rubber F2311. The experiments on thermal stability demonstrated F2311 coating thickness should be no less than 3.6 nm. These results were further confirmed by EXPLO5 thermo dynamic calculation. Calculated results showed that reaction characters of F2311 encapsulated Al exceeded conventional nano Al regardless of combustion and explosion. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), laser particle size analyzer and X-ray photoelectron spectroscopy (XPS) were used to characterize coated products' morphology, particle size distribution and interfacial bonding information. The results showed that the coated samples were generally spherical shape, with median particle size of 217.7 nm and coating thickness of 3.6 nm. The coating shell contained a small amount of alumina and aluminum fluoride besides fluoropolymer. The non-isothermal dynamic equations of Al/F2311 and Al/AlO were deduced by TG/DSC simultaneous thermal analysis. Compared with conventional nano-Al, the apparent activation energy of Al/F2311 decreased by 45 kJ/mol and the first exothermic peak temperature was about 10 °C earlier. Moreover, heat release was nearly twice as conventional nano-Al. TG-DSC-MS coupled measurements certified that active Al was enveloped by 'fluorine atmosphere' while F2311 decomposed in range of 200-400 °C. Alumina was replaced with aluminum fluoride inside coating layer during 400-550 °C, which broadened the diffusion path and then accelerated the permeation of oxidizing gas. In addition, the exothermic of Al-F was obviously larger than Al-O. Consequently, the oxidation reaction was activated rapidly, especially in initial exothermic period. Fluoropolymer encapsulated sub-micron sized Al was a latent highly activity energetic fuel and a potential candidate for aluminum powder.

ZHENG D W , HUANG T W , XU B , et al. 3D Printing of n-Al/polytetrafluoroethylene-based energy composites with excellent combustion stability [J ] . Advanced Engineering Materials , 2021 , 23 ( 5 ): 2001252 - 2001259 .

PANG W Q , LI Y , DELUCA L T , et al. Effect of metal nanopowders on the performance of solid rocket propellants:a review [J ] . Nanomaterials , 2021 , 11 ( 10 ): 2749 - 2760 .

AO W , LIU P J , LIU H , et al. Tuning the agglomeration and combustion characteristics of aluminized propellants via a new functionalized fluoropolymer [J ] . Chemical Engineering Journal , 2020 , 382 : 122987 - 122997 .

UHLENHAKE K E , YEHIA O R , NOEL A , et al. On the use of fluorine-containing nano-aluminum composite particles to tailor composite solid rocket propellants [J ] . Propellants, Explosives, Pyrotechnics , 2022 , 47 ( 7 ): e202100370 .

WANG H Y , REHWOLDT M , KLINE D J , et al. Comparison study of the ignition and combustion characteristics of directly-written Al/PVDF, Al/Viton and Al/THV composites [J ] . Combustion and Flame , 2019 , 201 : 181 - 186 .