Packed Colloidal Phases Mediate the Synthesis of Raspberry-Structured Microgel Heteroaggregates

Hybrid nanoparticles with complex architectures combine the properties of two distinct materials and integrate them to synergistically provide new characteristics to the assembly. In this work we demonstrate the ability to decorate the surface of a variety of micrometer-sized "core" particles with responsive microgels, forming raspberry-like particles. We use a templating technique wherein the microgel coating is applied from a high-volume-fraction colloidal phase, leading to high surface coverage and enhanced colloidal stability of the resultant particles. Concentrated colloidal dispersions enable microgel/core combinations driven by both specific and nonspecific interactions and offer improved coverage relative to dilute heteroaggregation. This approach is versatile and allows both the core material and microgel phase to be altered while still remaining effective. Though the recovered particles are highly diluted, recycling the unincorporated microgels following raspberry-like particle isolation and reforming the packed colloidal assembly allow multiple cycles of particle synthesis, which improves overall yield.