Patchy particles, which bear surface anisotropy through variation in surface composition, have been of great interest due to their ability to self-assemble into more complex superstructures and have applications in photonic crystals, targeted drug delivery and catalysis.1 One emerging approach to synthesize patchy particles is to tether two immiscible polymers on the surface of the nanoparticle that will spontaneously phase separate. Although there is an increasing interest in polymer-based patchy particles, most of the studies have been theoretical rather than experimental due to difficulties in preparing large scale quantities of nanoparticles with controlled polymer ratios, as well as a lack of characterization techniques for nanoscale phase separation. In the present work, we fabricate patchy particles using spherical ZrO2 nanoparticles with different ratios of the classical hydrophobic-hydrophilic polymer system (polystyrene and polyethylene oxide) using a simple ligand exchange procedure.2 In addition, we apply this method to other non-spherical metal oxide nanoparticles (TiO2 nanorods) and we incorporate the use of a pH and temperature responsive polymer (poly(2-vinyl pyridine)) in combination with polystyrene and polyethylene oxide. Solution and solid-state NMR experiments were designed to characterize the polymer composition on the surface and phase separation on different length scales, whereas microscopy techniques were used to characterize the assembly structures formed upon selective solvent exposure and pH variation.

Characterization of stimuli-responsive patchy nanoparticles by solid-state NMR

ACS Fall 2020 Virtual Meeting

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