Interrogating helical nanorod self-assembly with fractionated cellulose nanocrystal suspensions

The helical self-assembly of cholesteric liquid crystals is a powerful motif in nature, enabling exceptional performance in many biological composites. Attempts to mimic these remarkable materials by drying cholesteric colloidal nanorod suspensions often yield films with a non-uniform mosaic-like character, severely degrading optical and mechanical properties. Here we show---using the example of cellulose nanocrystals---that these problems are due to rod length dispersity: uncontrolled phase separation results from a ...