Oscillations, travelling fronts and patterns in a supramolecular system

International audienceSupramolecular polymers such as microtubules operate under non-equilibrium conditions to drive crucial functions in cells such as motility, division and organelle transport. In vivo and in vitro size oscillations of individual microtubules (dynamic instabilities) and collective oscillations have been observed. In addition, dynamic spatial structures like waves and polygons can form in non-stirred systems. Here we describe an artificial supramolecular polymer made of a perylene diimide derivative that displays oscillations, traveling fronts, and centimetre-scale self-organized patterns when pushed far from equilibrium by chemical fuels. Oscillations arise from a positive feedback due to nucleation-elongation-fragmentation, and a negative feedback due to size-dependent depolymerisation. Traveling fronts and patterns form due to self-assembly induced density differences that cause system-wide convection. In our system, the species responsible for the non-linear dynamics and those that self-assemble are one and the same. In contrast, other reported oscillating assemblies formed by vesicles, micelles, or particles rely on the combination of a known chemical oscillator and a stimuli-responsive system, either by communication through the solvent (e.g., by changing pH), or by anchoring one of the species covalently (e.g., Belousov-Zhabotinsky catalyst6,). Designing self-oscillating supramolecular polymers and large scale dissipative structures bring us closer to create more life-like materials that respond to external stimuli similarly to living cells, or to create artificial autonomous chemical robots