Surface Functionalization and Electrical Discharge Sensitivity of Passivated Al Nanoparticles

Abstract

Passivated aluminum nanoparticles are surface functionalized to elucidate their sensitivity against an electrical discharge. Two size fractions that differ in surface morphology are investigated. Electronic interactions between the partly inert, partly energetic organic molecules used for surface functionalization and the alumina surface are analyzed in detail. The nanoparticle surfaces are modified with the well-established, inert 2-[2-(2-methoxyethoxy)ethoxy]acetic acid, whereas energetic surface modification is achieved using 1,3,5-trinitroperhydro-1,3,5-triazine or the acidic and aromatic 2,4,6-trinitrophenol. A mechanistic model for the chemical surface functionalization of Al nanoparticles is hypothesized and corroborated by comprehensive optical and Fourier transform infrared spectroscopy studies. The surface structures are adjusted by developing a tunable stabilization procedure that prevents sedimentation and hence increases the saturation concentration in the liquid phase and finally affects the sensitivity character in view of electrical discharge ignition of dry powders. Detailed material characterization is conducted using transmission electron microscopy, combined with energy-dispersive X-ray spectroscopy and various absorption spectroscopy techniques (steady state in the infrared and ultraviolet/visible regime). The adjustment of surface structures of the distinct Al nanoparticle samples offers a valuable tool for tuning and tailoring the reactivity, sensitivity, stability, and energetic performances of the nanoparticles, and thereby enables the safe use of these multipurpose nanoparticles.

Degradation of tetrabromobisphenol A (TBBA) with calcium hydroxide: a thermo-kinetic analysis

“…The fingerprint region for pure TBBA starts from a strong absorption peak at 1454 cm −1 owing to the presence of aromatic C–C bonds, a strong phenolic O–H bending at 1378 cm −1 , strong aromatic C–O stretching at 1256 cm −1 , strong C–C–O asymmetric stretch of alcohols at 1020 cm −1 , strong CC bending at 980 cm −1 , strong C–H aromatics bending at 873 and 735 cm −1 along with strong C–Br and aromatic C–Br stretching vibrations at 673 and 564 cm −1 respectively. 15,53–56 The biochar analysis of pyrolyzed TBBA in Fig. 3b shows that there is a substantial reduction in the absorption peaks notably in the fingerprint region.…”

On the Use of Fluorine‐Containing Nano‐Aluminum Composite Particles to Tailor Composite Solid Rocket Propellants

“…Attempts at formulating aluminum/fluoropolymer composite non-propellant energetics systems have led to specific interest in the nano-aluminum (nAl)/fluoropolymer composites due to the high specific surface area of the reactants, which increase the reactivity of the system by significantly reducing the physical separation between the fuel and oxidizer, thereby resulting in kinetically governed combustion regimes that are not limited by the diffusion of fuel and oxidizer species into the reaction zone [19]. Some approaches have included embedding nAl into fluorinated epoxy-based matrices [20,21], electrospray deposition of nAl/ PVDF composites [22][23][24], surface functionalization of nAl [25][26][27][28][29][30][31], fluoropolymer-coated nAl composites [32,33], loose-powder nAl/PTFE systems [5,34], and mechanically activated Al/fluoropolymer additives [2][3][4]35]. More recently, additive manufacturing of nAl/fluoropolymer composites has enabled unique geometries and tailorability for Al/fluoropolymer additives.…”

Ultrathin Zirconia Passivation and Stabilization of Aluminum Nanoparticles for Energetic Nanomaterials via Atomic Layer Deposition

“…Surface passivation of Al nanoparticles is a common method to enhance the stability of Al nanoparticles. − The passivation films can be classified into two categories depending on the materials, both of which should have good oxidation resistance and are thin enough to maintain the weight percentage of metallic Al. , The first type is an organic coating such as toluene, isopropyl alcohol, perfluorodecalin, alkyl-substituted epoxides, and varieties of organic acids. − These organic coatings can effectively resist humidity; however, they are still permeable to oxygen and water at high temperatures, which can lead to the oxidation of internal metallic Al . The second type involves an inorganic passivation film represented by alumina (Al 2 O 3 ) and silica (SiO 2 ), which can be formed by either internal oxidation or external chemical coating. ,,, Although the Al 2 O 3 coated Al nanoparticles exhibit good stability at 60 °C with a relative humidity of 90%, the thick Al 2 O 3 coatings (≥5 nm) prepared by a thermal oxidation process have greatly reduced the weight percentage of metallic Al. , Moreover, the Al 2 O 3 coatings have exhibited a limited resistance under more harsh conditions, such as higher temperature and humidity, which will lead to the further loss of metallic Al.…”