We report on work based on the Brownian Dynamics simulation of interacting spherical colloidal particles leading to the formation of aggregated gel networks. The basic model incorporates the Brownian diffusion of soft spheres interacting via pair-wise surface-to-surface bonds and an optional long-range non-bonded interaction. Many-body hydrodynamics are neglected, apart from the drag effect. Surface bonds restrict angular reorganisation of aggregates during and after gelation, which allows the formation of a stable, percolating, three-dimensional network structure. We also describe the non-linear rheology of these systems in relation to their structure in response to constant strain-rate or constant stress (shear and elongational deformations). Allowing bond breakage enables the study of structural disruption in response to large deformations, and in this case the accompanying interparticle stress response reveals a distinctive stress overshoot characteristic of viscoelastic materials. The model has recently been extended to 16-segmented flexible casein xhains, which are formed by permanent bonds between nearest neighbours along the chain.
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