Orientation dynamics of stiff polymeric nanoparticles

Hydrodynamic assembly of elongated nanoparticles is of paramount importance for producing large and ordered structures with excellent functionalities. However, performing such bottom-up assembly, where diffusion processes play a fundamental role, necessitates quantification of the nanoparticle dynamics in flowing systems. In this presentation, we expose for the first time an experimental method for characterizing the orientation dynamics of nanorod suspensions in a flow also used for assembly. The parameters controlling the dynamics are investigated. The concept, based on birefringence relaxation, is demonstrated by flowing nanocelluloses (cellulose nanocrystals and nanofibrils), used as model systems, through a flow-focusing channel but it can be easily extended to different flows and to various birefringent nanoparticle suspensions.