THERMODYNAMICS OF CHEMICAL ENGINES: A CHEMICAL REACTION NETWORK APPROACH

Chemical processes in closed systems inevitably relax to equilibrium. Energy can be employed to counteract such tendency and drive reactions against their spontaneous direction. This nonequilibrium driving is implemented in open systems, which living organisms provide the most spectacular examples of. In recent years, experiments in supramolecular chemistry, photochemistry and electrochemistry demonstrated that, by opening synthetic systems to matter and/or energy exchanges with the environment, artificial systems with life-like behaviours can be realized and used to convert energy inputs of different nature into work at both the nanoscopic and the macroscopic level. However, one tool that is still lacking is a firm grasp of the thermodynamics of these chemical engines. In this thesis, we provide it by leveraging the most recent developments of the thermodynamic description of deterministic chemical reaction networks. As main theoretical results, we extend the current theory to encompass nonideal and light-driven systems, thus providing the fundamental tools to treat electrochemical and photochemical systems in addition to the chemically driven ones. We also expand the scope of information thermodynamics to bipartite chemical reaction networks characterized by macroscopic non-normalized concentration distributions evolving in time with nonlinear dynamics. This framework potentially applies to almost every synthetic chemical engine realized until now, and to many models of biological systems too. Here, we undertake the thermodynamic analysis of some of the epitomes in the field of artificial chemical engines: a model of chemically driven self-assembly, an experimental chemically driven molecular motor, and an experimental photochemical bimolecular pump. The thesis provides a thermodynamic level of understanding of chemical engines that is general, complements previous analyses based on kinetics and stochastic thermodynamics, and has practical implications for designing and improving synthetic systems, regardless of the particular type of powering or chemical structure.