Inspired by the scanning probe block copolymer lithography process,hollow silica shells were loaded with polymer-metal ink mixtures and investigated assolution-based nanoreactors for the synthesis of gold nanoparticles. The incorporationof poly(ethylene oxide) (PEO) into these hollow silica nanoreactors (approximately 40nm in size) and the use of a two-step reductive annealing process (first at 200 °C andthen at 600 °C) results in a high yield (76%) of larger (~6 nm) single nanoparticles;when the polymer is not used, smaller (~3 nm) particles dominate, and the yield ofsingle particles is only 6%. It was determined that particle coarsening mostly occurs inthe temperature range where the polymer is present and not degraded (i.e., <400 °C forPEO), as indicted by correlative in situ scanning/transmission electron microscopy in areductive gas-phase environment. Thus, polymer incorporation in this nanoreactorsystem, which is amenable to scale up, drives the complete conversion of nanoreactor contents without excessive metal loss,highlighting the impact of nanoreactor composition and structural design on particle synthesis.
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