Molecular chirality controls droplet division and helical fiber formation in liquid crystal emulsions
Molecular chirality is a source of broken mirror symmetry, but using it to control mesoscale structures with a tunable length scale remains challenging. Here, we demonstrate that adding a chiral dopant to nematic liquid crystal droplets bounded by a deformable two-surfactant interface controls their morphogenesis: the ratio of droplet diameter to cholesteric pitch determines whether droplets divide asymmetrically or symmetrically upon cooling, and whether they transform into single- or double-strand helical fibers. The fiber periodicity and thickness both scale linearly with the cholesteric pitch, which varies by less than 2% with temperature across the self-shaping window. Numerical simulations reveal that chirality-driven elastic stresses at the interface destabilize the droplets and trigger cusp-mediated shape transformations. These results establish cholesteric pitch as a design variable to precisely control droplet division and decouple the dimensions of spontaneously formed mesoscale structures from temperature dependence.