Probing nonlinear rheology layer-by-layer in interfacial hydration water

Bongsu Kim, Soyoung Kwon, Manhee Lee, QHwan Kim, Sangmin An, and Wonho Jhe

Viscoelastic fluids exhibit rheological nonlinearity at a high shear
rate. Although typical nonlinear effects, shear thinning and shear
thickening, have been usually understood by variation of intrinsic
quantities such as viscosity, one still requires a better understanding
of the microscopic origins, currently under debate, especially
on the shear-thickening mechanism. We present accurate measurements
of shear stress in the bound hydration water layer
using noncontact dynamic force microscopy. We find shear
thickening occurs above