Department of Mathematical Science Colloquium- Bottom up modelling of liquid crystals: from molecule

Bottom up modelling of liquid crystals: from molecules to applications

Liquid crystals (LC), with their unique combination of fluidity and anisotropic physical properties, continue to offer a number of novel fascinating applications, ranging from optical and haptic displays to organic electronics devices, sensors, etc... However, the relation between a certain molecular structure and the possibility of forming LC phases is still far from being understood. Modelling and computer simulations methods that address this problem at various length scales: mesoscopic, molecular, and atomistic have seen a huge development in the last few years, due also to the impressive increment in computer power. Thus, on one hand, coarse grained models, where molecules or molecular fragments are replaced by simple objects with similar shape endowed with attractive and repulsive interactions can now be employed to handle systems as complex as LC elastomers, explaining some of their unusual mechanical properties. On the other hand, atomistic molecular dynamics (AMD) simulations have started to make detailed and fairly reliable predictions of phase transition temperatures, order and other properties of real liquid crystals starting from their chemical structure. An even more exciting development is the possibility of studying the interaction of liquid crystals with solid surfaces and predicting their alignment. This is particularly important since, for most practical applications, LC are not used in bulk quantities but in micro or nano thick films, where the LC is oriented along a specific direction with the help of surface interactions. In the talk we plan to show that atomistic MD can now shed some light also on the interfacial behavior of liquid crystals, separating various effects that contribute to alignment, e.g. chemical nature of the substrate, morphology, roughness, surface treatments like rubbing and possibly suggesting way of optimizing devices. A view of the perspectives for future developments of the field will also be briefly discussed.

Event poster (pdf)