Nano-Real Space Analysis Takes Dynamics of Colloids Three Decades Closer to the Glass Transition

Glasses are among the most widely used of everyday materials, yet the process by which a liquid’s viscosity increases by 14 decades to become a glass remains unclear, as often contradictory theories provide equally good descriptions of the available data. Knowledge of emergent lengthscales and higher-order structure could help resolve this, but this requires time-resolved measurements of dense particle coordinates—previously only obtained over a limited time interval, and a some means of determining local free energy in model glassformers such as hard spheres [1]. Here we present an experimental study of a model colloidal system over a dynamic window significantly larger than previous measurements, revealing structural ordering more strongly linked to dynamics than previously found. Furthermore we find that immobile regions and domains of local structure grow concurrently with density, and that these regions have low configurational entropy [2].

[1] Robinson JE, Turci F, Roth R and Royal CP “Morphometric approach to many-body correlations in hard spheres” ArXiV 1809.02401 (2018).
[2] Hallett JE, Turci F and Royall CP, “Local structure in deeply supercooled liquids exhibits growing lengthscales and dynamical correlations”, Nature Comms. 9 3272 (2018).