(295g) Linear Viscoelasticity of Nanocolloidal Suspensions from Probe Rheology Molecular Simulations

Over the last two decades, both the experimental techniques and the theoretical framework have been well-established to carry out the microrheological investigation of soft matter systems. In this work, we have used an analogous probe rheology molecular simulation technique to investigate the linear viscoelasticity of nanocolloidal suspensions. The molecular model of the nanocolloidal suspensions that was recently developed by us¹ was employed for this study. Probe rheology simulations were performed in both the active and the passive modes. In the active mode, symmetric distribution of the colloidal particles around the probe is observed at all volume fractions and frequencies investigated, an observation that indicates that the system exhibits linear response at all conditions. In the passive mode, the probe motion is observed to change from ballistic on a very short time scale to diffusive on the long time scales studied. The elastic and the loss modulus values obtained from the active and the passive probe rheology simulations are in good agreement with those obtained from the bulk rheology simulations. The values of system parameter ranges (e.g. probe particle-colloid particle size ratio, amplitude of the applied force, etc.) that are required for the successful application of the probe rheology technique will be presented. The ability of the probe rheology molecular simulations to investigate the local viscoelasticity of nanocolloidal suspensions will also be discussed.

1. Sundaravadivelu Devarajan, D.; Nourian, P.; McKenna, G. B.; Khare, R. Molecular Simulation of Nanocolloid Rheology: Viscosity, Viscoelasticity, and Time-Concentration Superposition. Journal of Rheology 2020, 64 (3), 529-543.