Controlling Complex Coacervation with Tension

In this work, we investigate how mechanical forces influence the phase behavior of polyelectrolytes, providing new insights into complex coacervation. We apply controlled stretching forces to long, negatively charged polymers (e.g., hyaluronic acid or single-stranded nucleic acids) in a solution of shorter polycations. Our findings demonstrate that a sufficiently large force prevents these polymers from adopting compact conformations, effectively inhibiting phase separation. A critical force emerges, below which the stretched chain ultimately collapses and forms complexes with the polycations, with this threshold varying based on salt concentration and polycation length. We reference both simulations and analytical theory to interpret our results, offering a comprehensive view of the mechanical modulation of coacervation.