Investigation of Polymer Matrix Nano-Aluminum Composites with Pulsed Laser Heating by In-Situ TEM

The article of record as published may be found at https://doi.org/10.1002/prep.201900134Nanocomposites of aluminum and fluoropolymers react rapidly due to highly exothermic aluminum fluorination because of the high specific surface area nanoscale particles. In-situ transmission electron microscopy (TEM) techniques are invaluable for real time monitoring of the reactions in these systems at the nanoscale. Here, we investigated the reactions in nanoscale Al (nAl) and THV (terpolymer of tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride) and nAl-LDPE (low density polyethylene) composites, heated using a pulsed laser in a TEM. Results show that reactions are initiated at about 720 K, when THV starts to decompose, and proceed with the formation and growth of a hollow aluminum fluoride (AlF3) shell. Diffraction patterns revealed that this phase is the rare η-phase AlF3. In contrast, no reactions were observed in the inert nAl-LDPE composites. The experimental and theoretical results reveal that rapid pulsed laser heating and subsequent cooling of a nanoscale sample influences the phases that can form, and can be utilized to investigate other systems.This work was supported by the Young Investigator Program of Department of Defense Office of Naval Research (CBET-1437219)This work was supported by the Young Investigator Program of Department of Defense Office of Naval Research (CBET-1437219