Two-dimensional (2D) materials open up exciting possibilities for the study of ion transport behavior for green energy. Here, a simple and effective strategy to fabricate high-conductivity nanofluidic channels based on exfoliated montmorillonite (MTM) nanosheets is proposed. The resource-rich and low-cost layered MTM was first exfoliated into monolayer nanosheets using Exolit OP 550. Subsequently, the MTM nanosheets with Exolit OP 550 were assembled into 2D nanofluidic devices by the layer-by-layer self-assembly method. The results show that Exolit OP 550 exfoliates different types of layered MTM into monolayer nanosheets with uniform contrast and integrity. The reconstructed Na-MTM nanofluidic device has the highest ionic conductance. The ionic conductivity of the Na-MTM 2D nanofluidic device was effectively improved after Li+ modification with a higher charge density. After further optimizing the content of Exolit OP 550, the ion conductivity of the MTM nanofluidic device reached 4.66 × 10-4 S cm-1, which is 55.3% higher than the highest known value among the same nanofluidic devices. Interestingly, this nanofluidic device exhibited a very high sensitivity in detecting water evaporation, which can reach 10-12 S s-1 in resolution. This economically viable strategy may advance the study of low-dimensional ion transport properties in new energy coatings and the design of evaporation detectors.

Hydrogels hold great potential for osmotic energy conversion due to their inherent low resistance, yet their application is limited by weak mechanical properties, low charge density, and unstable pore structures. To address these challenges, we propose a Hofmeister effect-mediated strategy to develop a tough and highly conductive nanofluidic hydrogel from carboxymethyl cellulose and polyvinyl alcohol. The resulting hydrogel exhibits a tensile strength of 17.7 MPa and achieves an osmotic power density of 12.6 W m-2 under a 50-fold salinity gradient, representing a 3402% and 368% increase over conventional hydrogels. This enhancement is attributed to the formation of a nanophase separation structure, where hydrophobic regions serve as physical crosslinks for excellent mechanical strength and swelling resistance, and hydrophilic channels function as "ion highways" for high ionic conductivity. Moreover, the highly charged nanopores induced by the salting-out effect boost ion selectivity. This design overcomes the traditional trade-off between mechanical stability and ion transport. Under a 500-fold salinity gradient, the power density reaches 38.4 W m-2, surpassing most state-of-the-art nanochannel membranes. This strategy demonstrates broad applicability across various hydrogel systems. This work offers a versatile, scalable route to fabricate high-performance nanofluidic hydrogel for efficient and durable osmotic energy conversion.

Blade-Free Planetary Mixer (BFPM) can rapidly and efficiently mix highly viscous materials because of the strong centrifugal forces generated by the planetary motion of the mixing vessel. The safety of energetic propellant slurry during BFPM processing is critical. In this work, the mixing performance and process safety of composite solid propellant slurry in a BFPM were investigated through morphology observation, mixing index analysis, temperature measurement, rheological testing, mechanical sensitivity evaluation, and thermal analysis. The results showed that the BFPM achieved safe, efficient, and uniform mixing of the slurry. Under the baseline condition of 1000 rpm, the mixing index reached 95.73% after 24 min, and the slurry temperature increased to only 31.1 °C. The influence of BFPM processing on slurry safety was mainly reflected in the spatial redistribution of energetic solid components and the solid-liquid mixing state. And mechanical sensitivity tended to increase in regions of higher apparent viscosity. Increasing the rotational speed and adopting alternating rotation promoted particle dispersion and reduced local apparent viscosity, but an excessively high rotational speed reduced thermal stability. Overall, 1200 rpm combined with alternating rotation was identified as the most suitable operating condition. This work provides a practical basis for the safe and efficient BFPM processing of energetic propellant slurries.

This study presents the preparation and characterization of an oxygen-rich photosensitive binder (ATPE-HC) based on acrylate-terminated polyether (ATPE). This binder serves as a novel matrix material for the vat photopolymerization-based 3D printing of solid propellants. Owing to its higher oxygen balance compared to conventional binders, ATPE-HC can partially replace ammonium perchlorate (AP) in propellant formulations, thereby creating space for incorporating more energetic components (e.g., CL-20, RDX). This contributes to maintaining or even enhancing the energy level. Furthermore, this binder is compatible with photopolymerization-based digital light processing (DLP) 3D printing processes, enabling not only the highresolution fabrication of complex geometries but also the good applicability for DLP 3D printing of solid propellants. It provides a new material foundation for manufacturing high-performance customized solid propellant grains.

To overcome conventional nano-catalysts' limitations in energetic materials, this investigation reports a novel micro/nano-hierarchical Al-based alloy coating catalyst consisting of an Al-core coated with an ultrathin Ni-alloy shell for application in aluminized propellants. The annealed Al@Ni-P-Cu variant exhibited a catalytic efficiency factor of up to 1.3 for burning rate enhancement from 6.29 mm/s to 8.19 mm/s at 3.0 MPa. The catalyzed propellant achieves temperature rising rate and pressurization rates of 3701 °C/s and 722.6 kPa/(g·s), corresponding to 2.49- and 5.81-fold increases over the baseline, respectively. It is suggested that the combustion catalysts could accelerate energy release and improve combustion completeness of aluminized propellants. Thermal decomposition analysis further reveals an accelerated decomposition process mediated by the surface-engineered coating. A mechanistic framework is proposed wherein the combustion catalyst promotes synergistic heat-mass-momentum transfer and accelerates reactions across the condensed phase, diffusion-reaction layer, and gas-phase flame via a heterogeneous catalytic sequence. This work illustrates how rational surface coating design and micro/nano integration can effectively modulate combustion performance, providing insights for next-generation high energetic solid propellants.

Energetic materials serve as critical energy sources for weapon systems and equipment. During manufacturing and storage processes, microcracks may form in these materials, posing significant safety risks. Self-healing materials capable of autonomously repairing microstructural damage have emerged as a promising solution to mitigate such hazards. Therefore, this study focuses on the self-healing property of hydroxyl-terminated polybutadiene (HTPB), a widely utilized binder in solid propellants. We develop a self-healing adhesive film (HP-SS) by reacting isocyanate-terminated polybutadiene (IPDI-HTPB-IPDI) with two dynamic chain extenders, bis(4-hydroxyphenyl)disulfide and bis(2-aminophenyl)disulfide. The optimized HP-SS exhibits exceptional healing efficiency of 96.0%. Through systematic optimization of chain extender content, a series of adhesive films with tunable hydrogen bond density and hard segment content are prepared. The synergistic effects of disulfide metathesis and hydrogen bonding on self-healing performance are comprehensively investigated, including the influence of healing duration, temperature, and molecular mobility. This work proposes a novel strategy for regulating HTPB-based self-healing systems by balancing soft/hard segment ratios and hydrogen bond interactions, providing insights for designing high-performance energetic composites.

A critical gap exists in understanding the combustion mechanism of thermoplastic hydroxyl-terminated polyether (HTPE) propellants, particularly the effects of oxidizer particle size distribution. This study innovatively demonstrates that the solid-liquid transition of HTPE binder fundamentally shifts the ignition pathway to a novel condensed-phase mechanism driven by surface reactions and liquid-phase encapsulation. By partially replacing coarse oxidizers with fine particles, we reveal their dual role: accelerating pyrolysis and enhancing condensed-phase exothermicity, while inducing non-monotonic ignition delay through competition between gas release and heat accumulation. Combustion tests show concurrent increases in burning rate and pressure exponent; with 30% fine ammonium perchlorate (AP), the burning rate rises 34.92% to 10.2 mm/s and the pressure exponent increases from 0.337 to 0.452. Furthermore, fine oxidizers significantly promote aluminum agglomeration, yielding products with d(9)(0) > 1300 mu m. A combustion model is established, elucidating the unique coupling among binder transition, oxidizer decomposition, and Al agglomeration. This research broadens and refines the mechanistic understanding of solid propellant ignition and combustion. It provides both experimental evidence and a theoretical foundation for regulating the energy-release behavior of HTPE propellants.

Traditional thermosetting hydroxyl-terminated polybutadiene (HTPB) binders are widely used in solid propellants for their excellent mechanical properties and chemical stability; however, they lack self-healing capabilities, leading to challenges in long-term reliability and damage repair under operational stress. To address these limitations, we developed a series of self-healable HPy-SS binders by incorporating synergistic dynamic hydrogen bonds and disulfide bonds through molecular design and formulated solid propellants with 80% solid content (ammonium perchlorate/aluminum powder) based on these binders. The HPy-SS binders were facilely synthesized with systematic adjustments to the disulfide/urea hydrogen bond ratio. The optimized HPy-SS3 binder exhibited a remarkable tensile strength self-healing efficiency of 96.1% at 60 degrees C over 48 h, coupled with superior thermal stability and enhanced chain segment mobility. The resulting propellants demonstrated thermal decomposition profiles and burning rates comparable to those made up from conventional HTPB counterparts, achieving a tensile strength self-healing efficiency of approximately 85.5% while maintaining thermoset structural integrity. This work offers a promising strategy for simultaneously improving the durability and repairability of solid propellants, with potential applications in advanced aerospace materials.

Hydroxyl-terminated polyether (HTPE)-based insensitive propellants exhibit unique combustion behaviors governed by their thermal stability and binder-phase dynamics. This study systematically investigates the ignition-combustion mechanisms of HTPE propellants through multi-scale characterization and modeling. Experimental results reveal that the HTPE binder forms a dynamic “liquid-phase lubricating layer” upon heating, delaying oxidizer decomposition and extending ignition delay times by an order of magnitude compared to conventional HTPB propellants. High-speed imaging and thermal analysis demonstrate that this layer modulates condensed-phase reactions, inducing cyclic Al particle agglomeration and stabilizing flame structures. The burning rate pressure index (0.337) aligns with composite propellant norms, confirming self-regulating combustion stability. A modified ignition delay model incorporating phase-change effects and a combustion framework integrating binder encapsulation dynamics further elucidate how HTPE's phase change decomposition behavior governs oxidizer gasification and flame propagation. These findings establish new insights into designing thermally stable, low-sensitivity propellants with tunable combustion performance.

While 3D printing technologies based on various curing methods like thermal curing, photopolymerization, solvent evaporation molding, and melt cooling have been extensively studied in the field of composite energetic materials (CEMs), recent advancements in multi-material, multi-nozzle, and acoustic resonance techniques are now enabling the fabrication of CEMs with highly complex architectures and novel formulations, including polymer-bonded explosives (PBX), propellants, and pyrotechnics. 3D printing provides a more convenient and reliable approach for the structural design and study of the structure-performance relationship in CEMs, which is challenging to achieve through traditional subtractive or equivalent material manufacturing. UV-curing 3D printing, as a rapid-curing 3D printing method, offers advantages such as superior safety, efficiency, and environmental friendliness over other methods, garnering significant attention in the 3D printing of CEMs. This paper focuses on UV-curing technology and provides a detailed overview of the research progress on various UV-curing 3D printing techniques in the field of CEMs. It also discusses the advantages of 3D printing in the design of structured CEMs charges. Finally, based on the current research status of 3D printing for CEMs, we summarize some existing issues and present our perspectives on future development trends.

To develop a binder system suitable for photocurable additive manufacturing of solid propellants, this study utilizes ethylene oxide-tetrahydrofuran copolyether (PET), a commonly employed binder in solid propellants, as foundational material. By modifying terminal groups, two photocurable binders are synthesized: allyl-terminated polyether (AUPET) and acrylate-terminated polyether (PUA). The exothermic behavior of photopolymerization and the mechanical properties of these binders are comprehensively investigated. PUA exhibits a significantly faster photopolymerization rate than AUPET, enabling rapid photocuring and molding. Both binders demonstrate photocuring capability in the presence of thiols. Mechanical property testing indicates PUA forms brittle films under self-curing conditions, with a tensile strength of 1.18 MPa and an elongation at break of 81.07%, whereas AUPET, upon curing in the presence of thiol, exhibits enhanced flexibility, showing a tensile strength of 0.37 MPa and an elongation at break of 587.49%. Additionally, incorporating a triazine ring structure significantly enhances the tensile strength of PUA and AUPET films, the presence of thiols improves their elongation at break.

The high sensitivity of HMX to external stimuli presents significant safety concerns, necessitating methods to enhance its stability. This study investigates the encapsulation of HMX using imine-based porous organic cages (POCs), specifically CC3, to regulate its decomposition process and improve overall safety. The HMX@CC3 composites were synthesized and characterized through surface morphology, structural, and thermal analyses. The results demonstrate that CC3 encapsulation significantly improves HMX’s thermal stability and reduces its sensitivity, as evidenced by increased resistance to impact, friction, and electrostatic sparks. This study concludes that CC3 enhances HMX’s safety without altering its crystalline structure, offering a promising approach to reducing the sensitivity of energetic materials. This research has significant potential for improving the safety and performance of energetic materials in military and aerospace applications.

Covalent adaptable networks (CANs) typically require external catalysts to facilitate efficient crosslinker exchange, which can limit the reprocessability of the network due to leaching and degradation of the catalyst. In this study, the use of catalysts was avoided by employing a bicyclo[3.3.1]nonane (BCN) bis-alkyl halide crosslinker with selenium-based neighboring-group-participation (NGP) to enhance the rate of bond exchange. This thermally mediated C─N alkyl exchange and the associated flow behavior enabled the intrinsically ionic network (which possesses antimicrobial properties) to be both chemically recycled and repaired and reprocessed under mild conditions. Furthermore, the dynamic behavior of the network can be regulated by the reversible redox responsiveness of selenium atoms within the network. This novel type of NGP-based CAN therefore has the potential to enrich designs for catalyst-free dynamic networks with high performance and modulated dynamicity.

High sensitivity of energetic oxidizers and difficulties in activating passivated aluminum during the ignition are two serious obstacles for safe and efficient application of aluminized explosives. Herein, a safe and highly reactive HMX@PDA@FG (HPF) dual-shell oxidizer was constructed through functionalizing octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) core with a bio-enhanced interface polydopamine (PDA) and a two-dimensional (2D) fluorine source fluorinated graphene (FG) via bionic and self-assembly strategies. The synergistic integration of FG and PDA coatings achieves a remarkable reduction in HMX sensitivity (the impact energy increase from 7 to 28 J and friction load weight increase from 108 to 160 N). The 2D structure of FG notably enhances heat transfer within the system and leads to more rapid and concentrated decomposition of HMX. Furthermore, HPF oxidizers feature significant combustive activation effects for nano-aluminum due to high fluorine content of FG. Aluminized mixture HPF-10/n-Al exhibits superior combustion reactivity and energy output. The combustion heat of HPF-10/n-Al reaches 14,770.8 kJ/g, nearly 1000 kJ/g higher than HMX/n-Al, while the peak pressure and pressurization rate are approximately 1.5 and 4.9 times higher than HMX/n-Al. Hence, modifying multifunctional fluorinated graphene coating and bioinspired interface polydopamine on HMX shows great potential in enhancing both safety and energetic performance of aluminized explosives.

This work reports a fluorescent porous organic cage (RCC7) with AIE characteristics, enabling highly sensitive detection of nitroaromatic explosives. The probe achieves a 2.14 ppb detection limit for picric acid through inner filtration, resonance energy transfer, and π-π interactions, and further demonstrates ambient visual detection using test strips.

In this work, laser patterning of Ti6Al4V alloy with varying patterning ratios and depths was conducted to demonstrate its great potentials to enhance the fracture toughness of adhesively bonded alloy joints under Mode II loading. The topography, microstructures, wettability and chemistry of the surfaces after laser patterning were examined, and the Mode II (shear mode) fracture toughness of the bonded joints, GIIc, containing different patterns were measured. The results show that longitudinal microgrooves fabricated by laser patterning can effectively remove organic contamination from the surfaces of alloy, activate the surface chemistry, and increase the surface roughness at different length scales. The patterned surfaces were covered by continuous, uniform and porous TiO2 oxide layers, with the thickness about 30-50 nm. As the depth of laser patterning increases, the geometry of microscopic grooves formed on the metal surface transitioned from an 'open' type to an 'interlock' type. Such an interlocking topography improved the values of GIIcfor the bonded interfaces most remarkably. In addition, this work also reveals that the toughening effect produced by longitudinal patterning was superior to that by transverse patterning.

Solvent processing hampers the reliability and energy density of self-healing binders for energetic materials. We report a solvent-free curing route for a Diels–Alder self-healing furanyl-terminated polybutadiene enabled by a functional external plasticizer, dibutyl phthalate (DBP), which acts not only to lower the viscosity of the binder but to disperse the high-melting bismaleimide, thereby driving crosslinked network formation. The 50 wt% DBP-plasticized film healed a pre-cut crack in 5 min at 120 °C and recovered nearly full mechanical properties after 24 h at 60 °C. Based on this binder system, a self-healing solid propellant with 80 wt% solid content was solvent-free cast into a dense and void-free grain that healed surface cracks within 5 min at 120 °C. This solvent-free approach overcomes the limitations of solvent-based processing and offers a viable fabrication route for self-healing energetic materials.

A polyurethane (PU) binder with high mechanical strength and effective self-healing capacity at moderate temperatures is essential for improving the safety of composite solid propellants. Herein, we developed a fluorinated ureido-4-[1H]-pyrimidinone polyurethane (FUPU) binder by functionalizing hydroxy-terminated polybutadiene-based PU with multilevel hydrogen bonds introduced through ureido-4-[1H]-pyrimidinone and fluorinated segments from hexadecyl fluoro-1,10-decanediol. These dynamic hydrogen bonds facilitated bond dissociation/recombination and energy dissipation, imparting FUPU with a tensile strength of 1.14 MPa, an elongation at break of 1066%, and a self-healing efficiency of 93.5% after 8 h at 60 °C. Composite solid propellants (SP-2) prepared using FUPU, ammonium perchlorate, and aluminum powder exhibited enhanced mechanical properties and achieved a self-healing efficiency of 78.11% after 8 h at 60 °C. Furthermore, the fluorinated segments reduced aluminum agglomeration during combustion, increasing the burning rate by 31.6% at 3.0 MPa. Collectively, these results offer a viable strategy for designing high-performance composite solid propellants.