Macroscopic Self-Assembly of Binary Crystals
Formed by Vigorous Shaking in a Music SLAM

Tribocharging of large particles results in a remarkable crystalline ordering of compact structures while being vigorously shaken as seen in upper right. This was set to the music of Michael Jackson's Beat It by graduate student Sarah Battat in her successful MRSEC SLAM.

Whitesides and Weitz are investigating the remarkable macroscopic self-assembly of large particles. By shaking a binary mixture of two different types of particles, they induced charges on the particles through tribocharging. The particles start in a random, disordered structure as shown in the left figure. After shaking the particles for several minutes, order begins to arise in the particles as they are shaken. Eventually they adapt a crystalline ordering of a binary two-dimensional crystal, as shown in the right figure. Remarkably, they retain this compact, ordered structure despite being vigorously shaken. This represents a new approach to creating macroscopic self-assembled structures. Graduate student Sarah Battat set this whole process to the music of Michael Jackson's Beat It with original lyrics in her MRSEC SLAM.

First-ever NSF-MRSEC Science Slam

George M. Whitesides (CCB) and David A. Weitz (Physics & Applied Physics)
2021-2022 Harvard MRSEC (DMR-2011754)