Aging of colloidal gels in microgravity

It is difficult to investigate the gelation process for long periods of time due to sedimentation under gravity. Sedimentation causes the delicate gel structures to collapse under their own weight, and we wish to understand what we'd see if this collapse does not occur. In this project, we look at microscope images of colloidal gels taken over 60 hours at the International Space Station by NASA. The gels use the depletion force, and the samples studied range from very sticky particles to barely sticky particles. We use particle tracking to study the structure and dynamics of the gels as they coarsen. We observe that with stronger attractive forces, particles form thick gel strands over time, whereas with weaker attractive forces, particles do not aggregate even at the longest timescales observed.