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Phase behavior in network-forming liquids : patchy particles, vitrimers, and water - Frank Smallenburg

Heinrich-Heine-Universität Düsseldorf

If you cool down a simple liquid far enough, it will eventually crystallize. At low temperatures, the lower energy of the crystal phase wins out over the higher entropy of the liquid, and thus crystallization is always thermodynamically favored. However, this picture can change when considering particles which can bind only to a handful of neighbors, and therefore form a network-like structure at low temperature. In this seminar, I will show how in a simple toy model for patchy particles, the flexibility of the interparticle bonds can be used to suppress crystallization. Using computer simulations and free energy calculations, we demonstrate that this can lead to a disordered liquid phase even in the limit of low temperatures, stabilized by the configurational entropy associated with the topology of the network. Extending this concept, we then explore the phase behavior of vitrimers, a novel type of polymer that consists of monomers which are linked in a network via switchable covalent bonds. Finally, we use bond flexibility to confirm the stability of the controversial liquid-liquid phase transition in a model for water.


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