Functionality in biological materials arises from complex hierarchical structures. Importantly, phase separation of liquid precursors is a powerful mechanism to organize soft and amenable compartments into hierarchical structures in a range of length scales. This liquid-liquid phase separation (LLPS) process is driven by various noncovalent intermolecular forces and influenced by multivalent interactions in macromolecules. LLPS in biology is a highly dynamic and kinetically regulated process, which creates various complex liquid morphologies, such as membrane-less organelle, bodies, puncta, droplets, and condensates. The precise control in the formation, maintenance, function, and dissolution of these structures can be achieved through reaction-driven chemical processes. We are exploring design rules for programming kinetically-trapped assembly by coupling chemical reactions with LLPS.