Abstract

In recent years, a new type of synthetic microparticle has captured the imagination of researchers across the physical and biological sciences. These so-called active colloids convert chemical or environmental free energy into irreversible directed motion. Impressively, the active force generated by the particles can lead to self-propelling speeds of tens of hundreds of microns per second. Active colloids challenge our theoretical understanding of nonequilibrium phenomena and simultaneously represent a potentially innovative approach to directed transport and material design at the microscale. In this talk, I will discuss one of the most striking features of active colloids, which is their rich and complex nonequilibrium phase behavior. Special emphasis will be given to motility-induced phase separation where purely repulsive active colloids undergo a liquid-gas phase transition. This talk will provide a quantitative understanding of this phenomenon by generalizing concepts in classical statistical mechanics and liquid state theory to active systems. This newfound understanding can be leveraged to improve the self-assembly of many complex colloidal structures using active colloids.