Authors: B.J. Thomas, E. Lloyd, E.A. Guliants, C.E. Bunker, P.A. Jelliss, S.W. Buckner
Affilation: Saint Louis University, United States
Pages: 362 - 365
Keywords: aluminum nanoparticles, alkene polymerization, core-shell nanoparticles, energetic nanomaterials
Aluminum nanoparticles (Al NPs) have long been utilized for high-density energy storage and small-scale hydrogen production. The enthalpy of reaction for the formation of aluminum oxide (-1675.7 kJ mol-1) is a major reason for aluminum’s use in energetics. However, the synthesis of these materials can be challenging as Al is so highly reactive in the presence of water and oxygen. Under controlled conditions, the end result is a 2-5 nm-thick oxide layer. However, a correlation exists between oxide layer thickness and oxygen-exposure time. Therefore, core-shell Al nanomaterials require passivation to prevent further growth of the oxide layer. We report on the use of alkenes as capping agents for Al NPs. The core-shell materials have high total Al content (~50-60%), high active, unoxidized Al content (>90%), and increased air stability (~6 weeks). Alkene polymerization appears to be induced by the nascent, electron-rich Al surface; therefore eliminating the need for a free-radical polymerization initiator. We present findings from powder x-ray diffraction (PXRD), differential scan calorimetry (DSC), and thermogravimetric analysis (TGA) that confirm the presence of elemental Al. Fourier-transform infrared spectroscopy (FT-IR) confirms polymerization of the alkene on the Al NP surface.