Synthesis and characterization of polymeric films with stress-altered aluminum particle fillers

Processing and characterization of films synthesized with the blade casting method were studied. The films include 80 nm average diameter aluminum (nAl) particles combined with a solvent–binder system composed of acetone and dimethylformamide (DMF) co-solvent and Poly(vinylidene fluoride) (PVDF) binder. The nAl powder was stress-altered by annealing to 300 °C then quenching at two different cooling rates to induce elevated dilatational strain and stress within the nAl particles. Moreover, the annealing and quenching process dehydrated and dehydroxylated the surface enough to cause stress-altered particles to create more viscous slurries that produced a more porous film microstructure than untreated (UN) nAl powder. Density functional theory calculations revealed defective (i.e., dehydroxylated and dehydrated) sites on the stress-altered nAl particle surface may be responsible for the differences in nAl + PVDF reactivity that showed a higher enthalpy for aluminum-fluorine interface reactions for stress-altered nAl particles. Further, faster quenching created delamination at the core–shell interface and promoted greater energy conversion via a weaker, unsupported oxide shell that became less of a barrier for diffusion reactions. Results from this study provide insight on optimizing nAl particle properties for energy conversion using a method that could be applicable to a range of filler materials and influence bulk film properties. Graphic abstract: [Figure not available: see fulltext.].