Title: A bioinspired approach to assembling complex colloidal matter

Speaker: Angus McMullen

Host: Zeb Rocklin

Abstract: When building blocks can move and stick to each other, they can self-assemble into new materials with exotic mechanical or optical properties. We can orchestrate colloidal self-assembly through the careful design of an individual building block's geometry and interactions. Typically, the blocks assemble piece-by-piece, like a jigsaw puzzle that assembles itself. This tactic, however, necessitates new orthogonal interactions with every additional building block. We take a different approach: folding a string of colloidal particles into desired geometries, echoing how polypeptides fold into proteins. By imposing a hierarchy of interactions, we find that we can select structures with near-perfect yield even with the most basic interaction sequences. This work presents an entirely new way to assemble colloidal structures and could be used to self-assemble mechanical or optical metamaterials such as a structure with a negative index of refraction.

Bio: Angus McMullen completed his PhD at Brown University in 2015, where he studied the physics of translocation through solid-state nanopores---nanoscale biosensors with applications in DNA sequencing. Switching fields and length scales, Angus moved to NYU for his postdoc, where he now studies the self-assembly and folding of flexible colloidal polymers.