C O M P L E X S Y S T E M S A N D B I O M E D I C A L S C I E N C E S

S C I E N T I F I C H I G H L I G H T S

5 6 H I G H L I G H T S 2 0 2 2 I

based smart materials. Of particular interest is the dynamics of the systems approaching an ordered and/ or a kinetically arrested state and the dynamics therein. To some extent, simulations have contributed to the current understanding of the phase behaviour and dynamic aspects such as the occurrence of glasses and gels of particles with anisotropic interactions. However, there is a clear lack of experimental studies relating the dynamics and stimuli-responsive self-assembled structures of anisotropic building blocks.

Fig. 45: Left: Variation of the normalised diffusion coefficient,

Deff(qm)/D0 with f/fg under different conditions. Right: 2D scattering patterns obtained at different f.

The results presented in this work concern the long- standing problem of the dynamics of a system consisting of anisotropic particles and the field-driven interactions within self-assembled phases and/or approaching a glass or a kinetically arrested state. At beamline ID02, ultra- small angle X-ray scattering (SAXS) and X-ray photon correlation spectroscopy (XPCS) were employed to investigate the external field-induced self-assembly and the resulting dynamics at the nearest-neighbour length scale for colloidal ellipsoids over a broad concentration

Fig. 46: a) Experimentally measured 2D scattering pattern for at 1000 mT. Azimuthal sector averages have been taken between two red (blue) arrows to study the structure and dynamics parallel (perpendicular) to the external field direction. b) Schematic representation

of the field-induced nematic phase, where the short axes of the particles are aligned along the direction of the field. Radial intensity profiles for different B along the (c) parallel and (d) perpendicular direction, respectively. Different colours correspond to different B. The black filled circles and the vertical dashed lines indicate the q values at which the dynamics was measured. Variation of Deff as a

function of q (e) parallel and (f) perpendicular to B, respectively, for different field values.