Researchers in the laboratory of Marcus Weck, professor in the NYU Chemistry's Molecular Design Institute, have published a study featured on the cover of Nature Materials called "Tunable Assembly of Hybrid Colloids Induced by Regioselective Depletion." Weck Group graduate students Mingzhu Liu (first author), Veronica Grebe and Xiaolong Zheng (alumnus) worked with colleague David Pine, of NYU Physics and Chair of NYU Tandon's Department of Chemical and Biomolecular Engineering.
Abstract: Colloidal particles featuring site-selective directional bonding have long been proposed as building blocks to achieve desirable colloidal superstructures with unique properties, such as photonic bandgaps. Strategies to achieve bonding directionality often rely on emulating the structures and bonding principles of simple molecules on the colloidal scale. Assembling colloidal particles using site-selective directional interactions into predetermined colloidal superlattices with desired properties is challenging to achieve. The NYU team exploits regioselective depletion interactions to engineer the directional bonding and assembly of non-spherical colloidal hybrid microparticles. The crystallization of a binary colloidal mixture can be regulated by tuning the depletion conditions. Triblock biphasic colloids with controlled aspect ratios assemble into various colloidal superstructures and superlattices featuring optimized pole-to-pole or center-to-center interactions. Polymorphic crystallization can be tuned and the abundancy of each form can be quantified using newly developed algorithms allowing for the investigation of crystallization processes in real time. The resulting ordered pattern could be used as templates to guide the assembly of predefined structures across multiple length scales. The research also opens the possibility to achieve directional and specific bonding of colloidal particles towards open-packed superlattices with rational particle design rather than complex functional group synthesis and surface modification. Reconfigurable assemblies are within reach given switchable depletion interactions achieved by using stimuli-responsive depletants. Overall, this new method presents a new robust strategy for programming the directional assembly of colloidal particles into superstructures with desired topology and properties.
This research was supported by the U.S. Department of Energy, the American Chemical Society and the National Science Foundation.