Optimizing the Interfaces of Energetic Textiles with Perfluorinated Oligomer-Coated Aluminum Nanoparticles: Implications for Metastable Intermolecular Composites

Abstract

Metal powders have long been utilized as the primary fuel component in many conventional pyrolant-based energetic materials. Significant enhancements to their energetic performance are realized with metal powders composed of nanometer-sized particles due largely to the increase in specific surface area (SSA). Reaching the greatest possible weight percent loading of metal nanoparticles requires optimization of the interface between the metal fuel and the polymer matrix. In this work partially fluorinated perfluorocyclobutyl (PFCB) microfibers loaded with nanothermite formulations, composed of aluminum nanoparticles (nAl) coated with different perfluoropolyether (PFPE) oligomers, were successfully fabricated via electrospinning to produce nonwoven mats of energetic thermite microfiber. The resulting energetic textiles were composed of high SSA microfibers with highly uniform fiber diameters at fuel loadings upward of 35 wt % nAl content well dispersed in the fiber matrix. The metalized fibers were found to have smaller and more uniform diameters and possessed nAl loadings an order of magnitude greater than our previously reported polystyrene-based electrospun fiber composites. Furthermore, characterization of fiber morphology, particle dispersion, flame propagation, and the thermal properties of the PFCB/PFPE/nAl based nanothermite textiles are presented in this work to demonstrate a sensitive dependence of many fiber characteristics on the interface between the coated metal particle fuel and the polymer matrix.

Cryogel-Templated Fabrication of n-Al/PVDF Superhydrophobic Energetic Films with Exceptional Underwater Ignition Performance

“…The two endothermic peaks correspond to the melting peaks of PVDF and Al, respectively. The pre-ignition reaction (PIR) of the Al 2 O 3 shell with HF produced by PVDF breakdown is represented by the exothermic peak at 325 °C [ 28 , 29 ]. PIR is found in a wide range of energetic n-Al/fluoropolymer combinations, including Al/PTFE, Al/PFPE, and Al/PVDF.…”

Thermal Data of Perfluorinated Carboxylic Acid Functionalized Aluminum Nanoparticles

“…The ATR-IR data of PFOA, PFDA, and PFTA coated nAL particles are shown in Figure 2, and compared with bare nAl particles and the respective neat PFCAs. For the PFCA-coated particles, the presence of a C=O stretch-characteristic of a carboxylic acid moiety coordinated to alumina in the ATR-IR spectra of the solvent washed particles (up to three times)-confirms the attachment of the carboxylate (−COO − ) end groups of the PFPE DC to the nAl surface via bridging mode, as identified by COO antisymmetric, and COO symmetric stretches at 1650 and 1480 cm −1 , respectively [1].…”

“…The data provided in this work are unpublished and were part of a larger embodiment of our work on "Optimizing the Interfaces of Energetic Textiles with Perfluorinated Oligomer-Coated Aluminum Nanoparticles: Implications for Metastable Intermolecular Composites" [1]. The relevance for providing these thermal data is to demonstrate to the broader community of experimental research in fluorine-containing oxidizers for metal fuels, an area that has been recently and extensively reviewed [2], a novel fluorinated solvent washing processing technique for improved intermolecular PFCA monolayers onto metal fuels.…”

Al@Polytannic Acid/Polyvinylidene Fluoride Nanoenergetic Films for Controlled Combustion

“…Al-based nanoenergetic composites are a new type of energetic materials mainly composed of Al nanoparticles (nAl) and oxidants (such as oxides and fluorides) − and have attracted much attention in the field of energetic materials. Due to the close contact of the reaction components at the nanoscale, they often exhibit high energy density, a fast and tunable reaction rate, short ignition delay time, and excellent combustion performance. − At present, they have wide applications in the fields of ignition and propulsion. , However, since the atomic activity on the surface of nAl is extremely high and unstable, their surface can be easily oxidized and form an Al 2 O 3 passivation layer. − As a result, the nAl with reduced reactivity first break open the Al 2 O 3 shell during the redox reaction, and then, the inside active nAl melted can overflow and undergo an exothermic reaction with the oxidant. ,, Therefore, the Al 2 O 3 nanolayer on the nAl surface has a direct influence on the energy performance of Al-based nanoenergetic composites, which may be the key to further optimize and regulate its reaction performance in addition to controlling the equivalence ratio of the Al fuel and oxidant.…”