Ion-Induced Formation of Nanocrystalline Cellulose Colloidal Glasses Containing Nematic Domains

Controlling the assembly of colloids in dispersion is a fundamental approach toward the production of functional materials. Nanocrystalline cellulose (NCC) is a charged nanoparticle whose colloidal interactions can be modulated from repulsive to attractive by increasing ionic strength. Here, we combine polarized optical microscopy, rheology, and small-angle scattering techniques to investigate (i) the concentration-driven transition from isotropic dispersion to cholesteric liquid crystals and (ii) salt-induced NCC phase transitions. In particular, we report on the formation of NCC attractive glasses containing nematic domains. At increasing NCC concentration, a structure peak was observed in small-angle X-ray scattering (SAXS) patterns. The evolution of the structure peak demonstrates the decrease in NCC interparticle distance, favoring orientational order during the isotropic–cholesteric phase transition. Small amounts of salt reduce the cholesteric volume fraction and pitch by a decrease in excluded vol...