Zhishuai Geng

Aromatic polyurethane elastomers offer intrinsic mechanical advantages, yet their bulky backbones are widely regarded as a steric liability that precludes the formation of ordered hydrogen‐bond networks essential for high toughness. This long‐standing conflict has consequently forced the field to rely on aliphatic precursors. To address this, we introduce thiabicyclononane‐pyridinium ionic crosslinkers to engage the aromatic hard segments through cation–π interactions. This strategy effectively transforms the inherent steric hindrance of benzene rings from an impediment into a potent driving force for assembling dense, hierarchical hydrogen‐bonded networks. The resulting elastomer (MA‐S) exhibits exceptional mechanical integration, featuring a high tensile strength of 60.3 MPa, an ultra‐high toughness of 283 MJ m ⁻³ , outstanding impact resistance and a fracture energy of 198 kJ m ⁻² . These properties stem from the synergistic energy dissipation of hydrogen bonds, dynamic covalent bonds, and cation–π interactions. In addition, these multiple dynamic bonds endow the material with remarkable mechanical property retention (>95%) after multiple thermo‐compression cycles. Furthermore, the aromatic‐rich architecture enables robust π–π interfacial integration with carbon fibers, demonstrating a viable route toward closed‐loop recyclable structural composites. Consequently, this work establishes a versatile molecular design paradigm for creating sustainable, high‐performance polyurethanes that successfully reconcile mechanical robustness with dynamic recyclability.

The block copolyether (HTPE) composed of polytetrahydrofuran and polyethylene glycol holds significant promise for preparing insensitive solid propellants. However, no corresponding photosensitive binder formulation has been available for the photopolymerization 3D printing of such propellants. In this study, a photosensitive binder formulation is developed using acrylate-terminated polyether (ATPE), obtained through end-group modification of HTPE, as the oligomer, hydroxyethyl methacrylate (HEMA) and caprolactone acrylate (CA) as reactive diluents, trimethylolpropane triacrylate (TMPTA) as the crosslinker, and N-butyl-N-(2-nitroxyethyl) nitramine (Bu-NENA) as the plasticizer. The effects of ATPE content, crosslinker content, and plasticizer ratio on mechanical properties are systematically investigated using orthogonal experimental. Based on the identified optimal levels, four distinct ATPE-HC# photosensitive binder formulations with varying ATPE contents are ultimately determined. The optimized ATPE-HC# binder films exhibit a low glass transition temperature, favorable processing characteristics, and excellent compatibility with Bu-NENA, ammonium perchlorate (AP), cyclotrimethylenetrinitramine (RDX), and aluminum powder. The results of DLP 3D printing show that ATPE-HC5# has good applicability for rapid photocuring 3D printing of solid propellants. This photosensitive binder strategy, derived from the HTPE molecular structure, significantly enhances both the production efficiency of propellant charges and the design capability of charge geometries through photopolymerization 3D printing.

This study presents the preparation and characterization of an oxygen-rich photosensitive adhesive (ATPE-HC) based on acrylate-terminated polyether (ATPE). This binder serves as a novel matrix material for the vat photopolymerization-based 3D printing of insensitive high-energy 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 while improving the insensitivity characteristics of the formulation. Furthermore, this binder is compatible with photopolymerization-based additive manufacturing processes, enabling not only the high-resolution fabrication of complex geometries but also offering potential for further optimization of the mechanical properties, energy characteristics, and safety performance of the propellant through formulation adjustments. It provides a new material foundation for manufacturing high-performance customized charges.

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.

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.

Multifunctional surface coatings with both antibacterial and flame-retardant properties are of great significance for enhancing the safety in critical applications. Herein, we report the development of a Ni-Co nanozyme-based composite coating that exhibits synergistic antibacterial and flame-retardant performance. The incorporation of dual-metal active sites within a hierarchical nanowire architecture endows the NiCo₂S₄ nanozyme with a mechano-catalytic antibacterial mechanism, enabling efficient and broad-spectrum bacterial inhibition. Additionally, the Ni-Co components facilitate the formation of a compact, highly graphitized char layer during combustion, serving as an effective physical barrier against heat and oxygen. As a result, the coating achieved a 23.6% reduction in the peak heat release rate (PHRR) while maintaining outstanding antibacterial performance. This work presents a promising strategy for the rational design of multifunctional composite coatings via nanozyme integration that meets the urgent need for advanced protection materials in safety-critical environments.

Poly(urethane-urea) elastomers (PUUEs) have gained significant attention recently due to their growing demand in electronic skin, wearable electronic devices, and aerospace applications. The practical implementation of these elastomers necessitates many exceptional properties to ensure robust and safe utilization. However, achieving an optimal balance between high mechanical strength, good self-healing at moderate temperatures, and efficient flame retardancy for poly(urethane-urea) elastomers remains a formidable challenge. In this study, we incorporated metal coordination bonds and flame-retarding phosphinate groups into the design of poly(urethane-urea) simultaneously, resulting in a high-strength, self-healing, and flame-retardant elastomer, termed PNPU-2%Zn. Additional supramolecular cross-links and plasticizing effects of phosphinate-endowed PUUEs with relatively remarkable tensile strength (20.9 MPa), high elastic modulus (10.8 MPa), and exceptional self-healing efficiency (above 97%). Besides, PNPU-2%Zn possessed self-extinguishing characteristics with a limiting oxygen index (LOI) of 26.5%. Such an elastomer with superior properties can resist both mechanical fracture and fire hazards, providing insights into the development of robust and high-performance components for applications in wearable electronic devices.