Structure and dynamics of dense colloidal ellipsoids at the nearest-neighbor length scale

Anisotropic particles are known to exhibit a richer and more complex phase behavior in comparison to their spherical counterpart. While the majority of the existing studies address structural properties, the dynamic behavior of anisotropic particles is a relatively lesser explored avenue. Using multispeckle ultra-small-angle x-ray photon correlation spectroscopy (USA-XPCS), we have carried out a systematic investigation of the structural and dynamic properties of colloidal ellipsoids at the nearest-neighbor length scale. The USA-XPCS measurements have allowed us to probe, as a function of the volume fraction, the q-dependent effective structure factor, S-eff(q), along with the effective long time diffusion coefficient, D-eff(q), for this anisotropic system. Our results indicate a scaling behavior of Deff(q) with 1/S-eff(q) from which we have estimated the effective amplitude function A(eff)(q), which can be directly related to the effective hydrodynamic function H-eff(q). A(eff)(q) shows a similar q dependence to that of S(q). Our investigation also allows for the precise determination of the volume fraction corresponding to the arrest transition.

Automated summary

Anisotropic particles exhibit richer and more complex phase behavior compared to their spherical counterparts, with dynamic behavior being a relatively less explored area. Using USA-XPCS, this study systematically investigates the structural and dynamic properties of colloidal ellipsoids at the nearest-neighbor length scale. Results reveal a scaling behavior of the effective long time diffusion coefficient with the effective structure factor, providing insight into the effective amplitude function and the volume fraction corresponding to the arrest transition.