(257d) Mechanism of Nanoparticle Synthesis in Reversible Ionic Liquid Systems

Nanoparticle synthesis with silylated amine reversible ionic liquids (RevILs) has been previously demonstrated to offer a unique alternative to traditional synthetic methods allowing for size control and facile deposition on to support surfaces; however, the mechanism of nanoparticle synthesis in these systems remains uncharacterized. Previous work hypothesized nanoparticles prepared with RevILs are formed via a reverse micelle mechanism in which nanoparticles are stabilized and templated within the aqueous core of the organized structures. In this work, diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY-NMR) is used to demonstrate that nanoparticles synthesized with 3-aminopropyltriethylsilane (APTES) RevIL are not formed through a reverse micelle mechanism but rather a switchable aggregation of the silylated amine that affords control over nanoparticle size via manipulation of RevIL structure and concentration. Diffusion measurements and ¹H NMR spectra indicate that there is no aqueous core present within RevIL structures; however, nanoparticle synthesis occurs within the RevIL aggregates allowing for control over nanoparticle size via manipulation of aggregation number. Further, it is shown that the addition of water to these systems has detrimental effects on the aggregation behavior of the ionic liquid molecules in solution causing disassembly of the ion pairs.