Patchy particles, with a small number of discrete domains patterned on the surface, have shown promise for many applications, including stabilization of Pickering emulsions and construction of meta-materials with unprecedented structures. Although many methods have been reported for the fabrication of patchy particles, it remains a challenge to prepare patchy nanoparticles (NP) with a size of tens of nanometers and the number of nanodomains (valency) from 1 to 10. We developed a polymer brush-based method for the fabrication of multivalent patchy NPs with a valency from 6 to 10, potentially from 1 to 10, by utilizing the intrinsic lateral microphase separation of binary mixed homopolymer brushes grafted on inorganic NPs with a radius comparable to the polymer sizes. Well-defined mixed poly(tert-butyl acrylate) (PtBA)/polystyrene (PS) brushes were grown from asymmetric difunctional initiator-functionalized, 20.4 nm silica NPs by sequential surface-initiated atom transfer radical polymerization and nitroxide-mediated radical polymerization. A series of mixed brush NPs with a constant PtBA Mn and various PS molecular weights and similar grafting densities for the two polymers were prepared. After being cast from chloroform, a good solvent for both grafted polymers, mixed brushes on silica NPs underwent lateral microphase separation, producing multivalent NPs on 2D substrates. Image analysis revealed a linear relationship between the valency and the core NP size. These mixed brush NPs can interact with each other, forming “bonds” via the overlap of nanodomains and changing the valency according to the environment. Moreover, with increasing PS Mn from below to above PtBA Mn, the bond formation changed from one polymer to another.

Multivalent hairy nanoparticles from brush microphase separation

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.