Nanoreactors for Studying Single Nanoparticle Coarsening

Jinan Chai†‡, Xing Liao‡§, Louise R. Giam‡§, and Chad A. Mirkin*†‡§

^†Department of Chemistry, ^‡International Institute for Nanotechnology, and ^§Department of Materials Science and Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, United States

J. Am. Chem. Soc., Article ASAP

DOI: 10.1021/ja2097964

The ability to observe intermediate structures as part of coarsening processes that lead to the formation of single nanoparticles (NPs) is important in gaining fundamental insight pertaining to nanostructure growth. Here, we use scanning probe block copolymer lithography (SPBCL) to create “nanoreactors” having attoliter volumes, which confine Au NP nucleation and growth to features having diameters <150 nm on a substrate. With this technique, one can use in situ TEM to directly observe and study NP coarsening and differentiate Ostwald ripening from coalescence processes. Importantly, the number of metal atoms that can engage in coarsening can be controlled with this technique, and TEM “snapshots” of particle growth can be taken. The size of the resulting nanostructures can be controlled in the 2–10 nm regime.