Constructing Highly Reliable and Adaptive Primary Explosive Composites for Micro-Initiator Assisting by a Hybrid Template of Metal-Organic Frameworks and Cross-Linked Polymers

Evaluation of a novel composite of expanded polystyrene with rGO and SEBS-g-MA

This study displays the effect of reduced graphene oxide (rGO) nanofiller and polystyrene-b-poly(ethylene-ran-butylene)-b-polystyrene-grafted maleic anhydride (SEBS-g-MA) on the optical, thermal, and mechanical features of expanded polystyrene (EPS). First, the thin films of pristine EPS and composites were prepared using solution cast method. The prepared films were subjected to fourier-transform infrared (FTIR), SEM, UV-visible spectrophotometer, thermogravimetric analysis/differential scanning calorimetry, and universal testing machine for structural, morphological, optical, thermal, and mechanical characterizations. Optical study revealed a significant increase in refractive index and absorption of composites than EPS. Indirect band-gap energy of EPS (~4.08 eV) was reduced to ~1.61 eV for rGO composite and ~ 2.23 eV for composite composed of rGO and SEBS-g-MA. Thermal analyses presented improvement in characterization temperatures such as T10, T50, Tp, Tm, and Tg of composites, which ultimately lead to the thermal stability of prepared composites than pristine EPS. Stress-strain curves displayed higher yield strength (46.62 MPa), Young's modulus (96.29 MPa), and strain at break (0.54%) for EPS+rGO composite than pure EPS having stress at break (1.01 MPa), Young's modulus (12.44 MPa), and strain at break (0.08%). Moreover, ductility with relatively higher strain at break (0.61%) and lower Young's modulus (79.32 MPa) and yield strength (32.98 MPa) was noticed in EPS+rGO+SEBS-g-MA composite than EPS+rGO composite film. Morphological analysis revealed a change in globular morphology of EPS and inhomogeneous dispersion of rGO in EPS to homogeneously dispersed rGO in EPS matrix without globules owing to the addition of SEBS-g-MA. The increase in compatibility of EPS and rGO due to SEBS-g-MA was also observed in FTIR spectra. RESEARCH HIGHLIGHTS: Here, the solution casting approach was used to create the composite film of EPS and rGO with globules of various sizes. After adding SEBS-g-MA, the shape altered to globular free films exhibiting homogenous dispersion of rGO in EPS matrix. An optical investigation showed that composite materials had a significantly higher refractive index and absorption than EPS. The optical, thermal, and mechanical investigations suggest that the produced composites may be a great substitute for virgin EPS, allowing for a wider range of applications.

In Situ Electrochemical Construction of CuN3@CuCl Hybrids for Controllable Energy Release and Self-Passivation Ability

Advanced energetic materials (EMs) play a crucial role in the advancement of microenergetic systems as actuation parts, igniters, propulsion units, and power. The sustainable electrosynthesis of EMs has gained momentum and achieved substantial improvements in the past decade. This study presents the facile synthesis of a new type of high-performance CuN3@CuCl hybrids via a co-electrodeposition methodology utilizing porous Cu as the sacrificial template. The composition, morphology, and energetic characteristics of the CuN3@CuCl hybrids can be easily tuned by adjusting the deposition times. The resulting hybrids demonstrate remarkable energy output (1120 J·g-1) and good laser-induced initiating ability. As compared with porous CuN3, the uniform doping of inert CuCl enhances the electrostatic safety of the hybridized material without compromising its overall energetic characteristics. Notably, the special oxidizing behavior of CuCl gradually lowers the susceptibility of the hybrid material to laser and electrostatic stimulation. This has significant implications for the passivation or self-destruction of highly sensitive EMs. Overall, this study pioneers a new path for the development of MEMS-compatible EMs, facilitating further microenergetic applications.

Metal-Free Hybrid Energetic Composites Based on Donor-Acceptor π-Conjugated Organic Energetic Catalysts with Enlightening the Laser Ignition Performance of Multi-Scale Ammonium Perchlorate

Photosensitive materials, such as energetic complexes, usually have high sensitivity and cause heavy-metal pollution, whereas others, like carbon black and dye, do not contain energy, which affects energy output and mechanical properties. In this work, donor-acceptor π-conjugated energetic catalysts, denoted as D-n, are designed and synthesized. Nonmetallic hybrid energetic composites are prepared by assembling the as-synthesized catalysts into multiscale ammonium perchlorate (AP). Composites containing catalysts and APs can be successfully ignited without the involvement of metals. The new ignition mechanism is further analyzed using experimental and theoretical analyses such as UV-vis-near-infrared (NIR) spectra, electron-spin resonance spectroscopy, and energy-gap analysis. The shortest ignition delay time is 56 ms under the experimental condition of a NIR wavelength of 1064 nm and a laser power of 10 W. At the voltage of 1 kV and the electric field of 500 V mm-1 , the laser-ignition delay time of D-2/AP hybrid composite decreases from 56 to 35 ms because D-2 also exhibits organic semiconductor-like properties. D-2/AP and D-12/AP can also be used to successfully laser ignite other common energetic materials. This study can guide the development of advanced metal-free laser-ignitable energetic composites to address challenges in the field of aerospace engineering.

Preparation of High-Energy ECPs by Retaining the Coordination Ability of Carbohydrazide Groups

In order to preserve the coordinating ability of the hydrazide group, we used retrosynthetic analysis to design and synthesize ligand furan-2,5-dicarbohydrazide and its complex [Cu(FDCA)(H₂O)ClO₄]_n(ClO₄)_n·nH₂O (ECPs-1·H₂O). The structure of the product was confirmed by single-crystal X-ray diffraction, infrared spectroscopy, and elemental analysis. The solvent-free target material ECPs-1 exhibited good thermal stability, sensitivity to mechanical stimuli, and excellent explosive properties. Furthermore, it had good potential for laser ignition and comparable detonation power to LA. The simple preparation method and inexpensive starting materials enriched the research on primary explosives.