Neutron diffraction study of aqueous Laponite suspensions at the NIMROD diffractometer

Area of Science:

• Materials Science
• Soft Matter Physics
• Colloid Science

Background:

• Dynamical arrest and aging are crucial phenomena in disordered materials like glasses and gels.
• Understanding structural evolution in arrested states is vital for both fundamental science and technological applications.

Purpose of the Study:

• To investigate the time-dependent structural evolution of aqueous Laponite clay suspensions.
• To identify aging signatures and characterize structural changes across multiple length scales.

Main Methods:

• Employed neutron diffraction using the near and intermediate range order diffractometer (NIMROD).
• NIMROD enables structural studies from atomistic (1 Å) to mesoscopic (300 Å) scales, bridging traditional scattering techniques.
• Examined two Laponite suspensions at varying weight concentrations.

Main Results:

• Observed distinct aging signatures in both gel and repulsive glass arrested Laponite suspensions.
• Aging phenomena are attributed to sporadic contacts between Laponite platelets over time.
• Discovered orientational and translational order in water molecules near Laponite surfaces, consistent with Laponite's crystalline structure.

Conclusions:

• The study provides evidence of aging in Laponite suspensions across a wide range of length scales.
• The findings elucidate the interplay between dynamical arrest, aging, and nanoscale water ordering in clay systems.
• This research offers insights into the structural dynamics of disordered soft matter.