Electric Field Induced Orientational Order in Suspensions of Anisotropic Nanoparticles

Abstract

Suspensions of anisometric dye particles in dodecane have been investigated by electro-optic methods and X-ray scattering. The suspensions have nematic like properties such as a Schlierren texture and an electro-optic response. The thin, plate-like, particles of Permanent Rubine are crystalline monodomains with a set of lattice planes spaced by 18 Å lying parallel to their largest faces. They are oriented by an electric field such that their normals tend to be perpendicular to the applied field. The stronger ordering at about 25 wt% suggests that this might be the onset of the nematic phase. A simple model shows that the electric field induced change in optical absorbance is consistent with the induced orientational order.

Keywords:

• Anisotropic nanoparticle suspension
• electric field ordering
• orientational order
• X-ray scattering

Acknowledgment

We are grateful for the financial support of an Open Innovation Research Award from Hewlett Packard.