Jorn Dunkel（MIT) Topological mechanics of passive and active tangles

Abstract

Knots determine the robustness and function of filamentous matter across a wide range of scales, from the intertwined yarns in ropes and fabrics to the tangled polymers in rubbers and gels. The extraordinary stability of knotted materials arises from the intricate interplay of mutual mechanical obstruction and contact friction between tangled filaments. In this talk, I will survey recent efforts by my group and our experimental collaborators to understand the mechanics and non-equilibrium dynamics of passive and active tangled matter. In the first part, we will discuss how opto-mechanical fibers can be used to formulate and test mathematical models for predicting the stability of elastic knots [1]. Once validated, such models enable us to investigate the practical potential of knotted structures and fields as topological batteries [2]. In the second part, we will explore an interesting class of active matter systems that can autonomously perform complex topological transformations. Drawing guidance from worm collectives that can self-organize into macroscopic tangles over the course of minutes but untangle within only a few tens of milliseconds, we identify and discuss generic design principles for active tangled materials [3].