Computer Simulations of Packed Soft Colloids

Soft colloids are micron-scale structured objects such as polymer microgels, that are compressible and deformable. Even at high packing ratios, a soft colloid may still be able to undergo cage-breaking due to particle deformation. The link between the detailed elastic properties of soft colloids and the resulting dynamics are presently not well understood. Soft colloids show rich rheological behaviour we wish to understand the links between the single particle elastic properties and the resulting rheology. We use a recently developed algorithm, Fluctuating Finite Element Analysis, for simulating viscoelastic objects undergoing thermal excitation. While symmetric soft particle potentials have been much studied, our approach captures the detailed shape deformations of the colloidal particles so that the structure and anisotropic deformation of the particles are taken into account. We investigate varying effective volume fraction and find evidence of cage-breaking events even where the effective volume fraction exceeds the close packed limit. Additionally, we present results of varying modulus and steady shear rates for a constant effective volume fraction.