Surface Gel Dynamics.

Gel systems have a complex surface topology that can easily deform. Understanding of gel interactions at surfaces is necessary for applications like medical sutures, underwater adhesion, contact lenses, etc. Light scattering techniques have been used to study the dynamics of gel systems in the bulk but, little is known about the interaction of these gel systems at surfaces. Here, we use Differential Dynamic Microscopy (DDM) paired with Confocal imaging and Dynamic Light Scattering (DLS) to study the network motion of Poly Vinyl Alcohol (PVA) gels and Hyaluronic Acid (HA) gels at heights ranging from 0 – 1000 nm away from a surface. Dynamics of gels with different cross-link densities are compared, and bulk measurements are confirmed with DLS. The confocal imaging paired with DDM gives an accurate sense of the location of the gel surface, its texture, and dynamics. We observe that gel network motion increases as we move from the surface to the bulk, concluding that the surface interaction changes local dynamics.