Attractive (non-self-assembling) aqueous cellulose nanocrystal
(CNC) suspensions were topologically tailored into isotropic gels
through the surface grafting of dialkyl groups. We thus focus on the
influence of CNC concentration, including for pristine CNC, surface
linker branching, branching degree, and the influence of side group
size and branch-on-branch surface-grafted groups. The resulting mobility
and strength of interaction in particle–particle interaction
mediated by the surface groups was investigated from a rheological
point of view. The emphasis is on nonlinear material parameters from
Fourier-transform rheology and stress decomposition analysis. The
results show that nonlinear material parameters are more sensitive
than linear viscoelastic parameters to the onset of weakly interconnected
networks in pristine CNC isotropic suspensions. All surface-modified
CNC suspensions resulted in isotropic gels. The nonlinear material
parameters were found to be broadly sensitive to CNC concentration,
branching, degree of branching and surface-grafted linkers’
length. However, the length of the grafted chains and the degree of
branching were the primary factors influencing the nonlinear material
response. Furthermore, the results showed evidence of two strain amplitude
ranges with distinct nonlinear signatures that could be attributed
to the disruption of weak network connection points and to distortions
of more dense (aggregate) network regions, respectively.