How do forces propagate and how are they distributed within soft
materials? In granular materials the answer to this questions
is
well known. However, for the case of colloidal hard spheres,
an
answer remains ellusive.
The objective of this project is to understand how colloidal
glasses distribute and bear external stress. We seek to measure the
distribution of forces at the boundaries of
“glassy”
colloidal silica, using confocal rheology. Our
method is
based on the application of a controlled shear stress to a
“glassy” colloidal silica sample. The sample is
composed
of bidisperse silica colloids in a dyed index matching
solvent.
The shear force is applied using a rheometer (Anton Paar MCR
301) with cone and plate geometry. Using a technique similar to
traction force microscopy, we observe the local force distribution at
the boundary of the glass.
