The human body is composed of biomolecules such as proteins and nucleic acids, which interact spontaneously to form various supramolecular structures, including compartments and fibrils. The properties of these structures, such as size and shape, depend on both the information encoded in the molecular sequence and the local environment. This innate ability of biological molecules to self-organize into functional structures lies at the core of life. Indeed, these structures coordinate the myriad biochemical activities necessary for cellular survival, growth, and reproduction. Much like factories, cells must efficiently coordinate numerous biochemical reactions in both space and time. Compartmentalization serves as a key strategy to achieve this coordination. Traditionally, biological studies have focused on membrane-bound compartments, where physical barriers separate them from the surrounding environment. However, recent research has revealed the existence of membraneless compartments, known as biomolecular condensates, which form through the phase separation of proteins and nucleic acids. This discovery has opened many questions regarding the molecular mechanisms governing the formation and properties of membraneless compartments, as well as the interplay between these compartments and biochemical reactions. This project has two primary objectives: a) to generate simplified models of biological membraneless compartments in vitro, allowing for the investigation of the physicochemical principles underlying their properties and their link with the modulation of biochemical reactions; b) to leverage this understanding to design novel molecules with programmable phase separation behavior which do no exist in nature. Special focus is given on studying enzymatic reactions and aggregation events within open compartments.