Chirality inversion in colloidal self-assembly

The chiral self-assembly of nanoscale building blocks offers a scalable route to functional materials, but understanding and controlling this process is a persistent challenge.

A notable example is cellulose nanocrystals (CNCs), elongated nanoparticles extracted from natural cellulose that assemble into a cholesteric liquid crystal phase in aqueous suspension.

This helicoidal self-organisation can be preserved into the solid state to create structurally coloured films, offering a sustainable way to produce next-generation pigments and colourants.

However, the CNC cholesteric phase is always found to be left-handed due to the presence of ""bundles"", a sub-population of CNCs that act as colloidal chiral dopants and induce left-handed ordering.

Inspired by the naturally-occuring CNC bundles, this project aims to produce cellulose polycrystals (CPCs), a new class of clustered nanoparticles produced by the aggregation of CNCs in the presence of a chiral ""glue"" provided by hemicelluloses.

These CPCs will then be used as synthetic chiral dopants to induce a right-handed cholesteric phase in CNCs suspensions for the first time.

This inversion of the handedness of CNC self-assembly will result in films that reflect RCP light in the visible range, enabling the creation of structurally-coloured materials with near-ideal optical performance.

These findings will deepen our understanding of chiral colloidal self-assembly and open up new avenues of enquiry for research on bio-sourced nanomaterials.