Self-propelling superballs

Abstract

This work demonstrates the synthesis and characterisation of novel selfpropelling colloidal superballs. The particles consist of haematite cubes with a silica shell, coated on one face with a thin layer of platinum. Platinum catalyses the decomposition of hydrogen peroxide, causing a concentration gradient around the particle that propels the particle forward. The goal of this research was to synthesise these self-propelling superballs and to quantify their single-particle behaviour. Various values and parameters were investigated to determine the effect of cubicity on the motion of active particles, including the diffusion coecient, persistence time and velocity. In addition, active motion as a function of peroxide concentration and temperature was mapped. Self-propelling superballs of roughly 1 m in size were successfully synthesised, with their effective diffusion coecient increasing with peroxide concentration and temperature. However, the developed analysis method, involving fitting of the mean squared displacement with a diffusion equation, was not robust enough to quantitatively describe swimming motion.