Mesophase transition of cellulose nanocrystals aroused by the incorporation of two cellulose derivatives.

Cellulose nanocrystals (CNCs) per their twisting structure and high aspect ratio and charged surface property are increasingly receiving great attention in chiral photonic crystal and pigment fabrication. However, the cholesteric mesophases of CNCs is unstable and easily destroyed by the additives with high M. In this work, hydroxypropyl cellulose (HPC) and carboxymethyl cellulose (CMC) are incorporated into CNCs for a continuous mesophase transition monitoring. We investigated the effects of HPC and CMC on the properties of CNCs with respect to the morphology, mesophase, rheology, and structure-color properties. Our results showed that the addition of CMC (≥ 1 wt%) prevented the formation of a continuous cholesteric phase but resulting in a fast gelation due to the strong repulsion between CMC and CNCs. Alternatively, the cholesteric phase was well-preserved in the CNC/HPC in which HPC (< 10 wt%) served as an efficient tuner of phase transition, color hue and rheology properties.