Spontaneous coiling of filamentous condensates during the demixing of structured fluids

Liquid-liquid phase separation, whereby two liquids spontaneously demix, is ubiquitous in industrial, environmental, and biological processes. Many such fluids exhibit liquid crystalline ordering, which can drive the formation of condensates with intriguing non-spherical shapes and dynamics. Here, we report the formation of filamentous condensates that spontaneously adhere and coil into helices during the growth of condensates with smectic A ordering. We confine filamentous condensates to microdroplets to investigate the stresses that dictate their shape evolution. When sufficiently long filaments contact themselves, an apparent adhesion force drives their zippering and winding into helices with a spontaneous emergent chirality, despite the absence of any chiral liquid crystalline phase. Polarized optical microscopy combined with theory suggests this adhesive interaction arises from rearrangements in the smectic microstructure made possible by partial filament coalescence, which reduces the global elastic distortion energy. We show how this microstructurally-mediated coiling drives filament networking in less confined Hele-Shaw cells, driving the spontaneous formation of sparse condensate networks with life-like dynamics. Understanding and controlling these dynamics may provide new avenues to direct pattern formation or template materials.