Hierarchical structured materials are ubiquitous in nature (e.g. bone, silk and wood). These remarkable self-organized structures exhibit a high degree of sophistication with excellent properties optimized by millions of years of evolution, making them great targets for materials chemists. Among them, the Bouligand structure, which is a continuously twisting lamellar structure found in various kinds of plants, crab shells and insects, endows creatures with iridescent colors due to its specific circular polarized light reflection property. Cellulose nanocrystals (CNCs) are a highly crystalline form of cellulose. Above a critical concentration, CNCs self-assemble into the cholesteric liquid crystal, which shows an analogous supramolecular structure and similar optical properties to the Bouligand structure. Therefore, artificial materials constructed from CNC liquid crystals will provide a feasible route to mimic Bouligand structures, producing materials with diverse optical properties.<br/>We have explored the unique optical properties of CNC assemblies and their applications as smart devices. We have discovered a new micelle-assisted self-assembly strategy to prepare freestanding films of CNCs that display circularly polarized reflection across the visible spectrum. This simple approach distorts the chiral nematic domains of CNCs with variations of helical pitch and orientation, leading to broadband polarization. Furthermore, a novel pressure responsive chiral photonic aerogel using CNCs was designed. This aerogel exhibits color change from scattering white to photonic iridescent under pressure due to the structural transition from a porous aerogel to a planar film. Benefitting from the color variation mechanism of the aerogel, a CNC-based solvent-sensitive ink that shows quick color response to different solvents was further produced. These materials could be important components in further applications such as sensors, probes and other artificial detectors.

Optical materials based on cholesteric liquid crystals of cellulose nanocrystals

Macromolecular Chemistry: The Second Century

[Author Benefits](https://scimeetings.acs.org/?utm_source=pubs_content_marketing&utm_medium=website&utm_campaign=0320_MCF_NPI_Launch_Spring_Homepage&ref=pubs_content_marketing)

[How to use SciMeetings](https://storage.googleapis.com/dl.morressier.com/acs/SciMeetings-ACSSpring2020-HowToGuide_M3020-Final.pdf)

[Frequently Asked Questions](https://storage.googleapis.com/dl.morressier.com/acs/SciMtng_ACSNMSp2020_FAQ_M3120_Final.pdf)

ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.