Tunable viscoelasticity of double gel networks: colloidal gel embedded in a hydrogel matrix

We create double gel networks consisting of a colloidal gel embedded within a hydrogel matrix. Depending on the relative strength between the two networks, we can tune the rheology to be either dominated by the colloidal gel, the hydrogel, or to exhibit features characteristic of both systems. This allows us to adjust both the sample modulus and the yielding behavior. Looking beyond the macroscopic mechanical characteristics, we discuss the changes in the microscopic dynamics of the colloidal gel occurring as the hydrogel network forms around it. We use differential dynamic microscopy and confocal fluorescence microscopy to access the variations in the structure and network fluctuations of the colloidal gel.