Figure 2: Protocols to prepare sunflower-like assemblies.
From: A design strategy for the hierarchical fabrication of colloidal hybrid mesostructures
(a) Both strategies begin with sonication of elongated PFS-b-P2VP micelles. (b) Addition of SiO2 NPs leads to adsorption of PFS-b-P2VP seed crystallites, but a large excess of seed crystallites remains in solution. (c) In the ‘seeded growth’ strategy, the seed-coated SiO2 NPs are first separated from the excess seeds. Then an aliquot of a concentrated solution of PFS-b-P2VP unimers is added, and the mixture is aged to form the mesoscale hybrid structures shown in d. In the ‘self-seeding’ strategy, the mixture in b is annealed at 90 °C, leading to the dissolution of the seed crystallites suspended in solution, but preservation of the crystallites bound to the surface of the SiO2 NPs. Upon cooling, micelles grow from the seeds on the NP surface to form hybrid structures indistinguishable from those formed via unimer addition. Both protocols create supersaturated solutions of the BCP in the presence of seed crystallites on the surface of the colloidal nanoparticles, followed by the epitaxial growth of the BCP micelles from the surface-bound seeds.
