Nonequilibrium network formation in soft materials

Gel networks are common in nature and in industry. As percolated, rigid networks they induce solid-like properties to fluids containing very low particle volume fractions. The kinetic entrapment of particles in the network keeps the system from freely exploring phase space towards the thermodynamic equilibrium state. The process by which they form is relevant to many sectors, including biology, medicine, cosmetics and the food industry. However, as a result of their out-of-equilibrium nature they are often not well understood using conventional thermodynamics; there is no all-encompassing theory that describes how they form, and what their resulting properties are.
In this thesis we study the formation of space spanning networks by experiments in various systems of colloidal particles, and simulations. We show that the formation of space spanning networks can occur by a nonequilibrium process, where detailed balance is broken and conventional statistical mechanics is not applicable (chapters 3,4). In particular cases, as our experiments with patchy particles confirm, the formation process of such a network can also take place via an equilibrium process, and lead to equilibrium gels (chapter 5). We also study properties of out-of-equilibrium materials that have already formed, and investigate space spanning networks of wetted salt crystals that contribute to the materials mechanical properties and dictate moisture transport and electrical conductivity (chapter 6). Finally, we visualize how internal strain builds up and form connected clusters of strain relaxation zones (chapter 7).