Aggregation dynamics of elongated particles confined at liquid surfaces or in nematic phases, a numerical model development
Résumé
Designing stable liquid crystal (LC) composites is one of the main tasks pursued by several members of the
IC1208 Cost action. Liquid crystal composites are however colloidal dispersions which have very specific
properties compared to the usual colloidal dispersions in simple liquids. LC matrices give indeed rise to longrange
attractive multipolar interactions between colloidal dispersions [1]. Strong dipolar interactions are mainly
observed at large scale, but even at the nanometer scale the interactions between two nanoparticles are
quadrupolar, weaker but often sufficient to yield aggregates in many systems [1]. Aggregation phenomena under
such multipolar interactions are still not fully understood, so to get a deeper understanding we have considered a
2D 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 quadrupolar capillary interactions. Furthermore the interactions between a group of already aggregated particles and a single one located at a large distance strongly depend on the spatial arrangement of the aggregated particles. This phenomenon is further complicated by the presence of possible direct solid-solid interactions, which would arise when the particles enter into contact and possibly freeze the aggregate shapes. Currently we are focusing on modeling the above described aggregation phenomena by developing a numerical code that is sufficiently accurate in order to catch the many-body interactions mentioned above in a simple way. Once this is achieved extensive comparison with experiments will be possible and the model system may be used to address open questions arising from the experiments. Our model is based on the 2D solution of the Young-Laplace equation to gain the forces acting on the particles, then moving each particle individually by solving the Newton equations based on classical discreet element methods. In this presentation I would like to give an insight into the current state 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
When elongated particles are trapped at a liquid interface they distort it and then interact via quadrupolar capillary interactions. Furthermore the interactions between a group of already aggregated particles and a single one located at a large distance strongly depend on the spatial arrangement of the aggregated particles. This phenomenon is further complicated by the presence of possible direct solid-solid interactions, which would arise when the particles enter into contact and possibly freeze the aggregate shapes. Currently we are focusing on modeling the above described aggregation phenomena by developing a numerical code that is sufficiently accurate in order to catch the many-body interactions mentioned above in a simple way. Once this is achieved extensive comparison with experiments will be possible and the model system may be used to address open questions arising from the experiments. Our model is based on the 2D solution of the Young-Laplace equation to gain the forces acting on the particles, then moving each particle individually by solving the Newton equations based on classical discreet element methods. In this presentation I would like to give an insight into the current state 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