Résumé
Designing stable liquid crystal (LC) composites is one of the main tasks pursued by several members of theIC1208 Cost action. Liquid crystal composites are however colloidal dispersions which have very specificproperties compared to the usual colloidal dispersions in simple liquids. LC matrices give indeed rise to longrangeattractive multipolar interactions between colloidal dispersions [1]. Strong dipolar interactions are mainlyobserved at large scale, but even at the nanometer scale the interactions between two nanoparticles arequadrupolar, weaker but often sufficient to yield aggregates in many systems [1]. Aggregation phenomena undersuch multipolar interactions are still not fully understood, so to get a deeper understanding we have considered a2D model system describing the classical dynamics of elongated particles at a liquid interface.
When elongated particles are trapped at a liquid interface they distort it and then interact via quadrupolarcapillary interactions. Furthermore the interactions between a group of already aggregated particles and a singleone located at a large distance strongly depend on the spatial arrangement of the aggregated particles. Thisphenomenon is further complicated by the presence of possible direct solid-solid interactions, which would arisewhen the particles enter into contact and possibly freeze the aggregate shapes. Currently we are focusing onmodeling the above described aggregation phenomena by developing a numerical code that is sufficientlyaccurate in order to catch the many-body interactions mentioned above in a simple way. Once this is achievedextensive comparison with experiments will be possible and the model system may be used to address openquestions arising from the experiments. Our model is based on the 2D solution of the Young-Laplace equation togain the forces acting on the particles, then moving each particle individually by solving the Newton equationsbased on classical discreet element methods. In this presentation I would like to give an insight into the currentstate of the development of the numerical model and our future objectives.
[1] Blanc, C., Coursault, D., Lacaze, E., Ordering nano-and microparticles assemblies with liquid crystals, Liquid Crystals Reviews, 1(2),pp. 83-109, (2013).12