Colloidal liquid crystal nanohybrids as building blocks for chiral materials

Symmetric & asymmetric cellulose nanocrystals with end-tethered polymer chains

One of the most practical strategies to produce materials with novel properties is through self-assembly of chemical building blocks into structures with nanoscale features. The building blocks of self-assembled structures can consist of small molecules, polymers or colloidal particles. Self-assembly of colloids, in particular, provides a simple means toward complex three-dimensional material structures. The further introduction of chirality, or handedness, into such porous solid materials may lead to favorable properties for applications including asymmetric catalysis, enantioselective separation/sorption media, biosensors, and optics. One attractive class of chiral colloidal building blocks are cellulose nanocrystals (CNCs), which are readily extracted from naturally abundant renewable resources. Unique among rod-shaped nanoparticles, CNCs form liquid crystal phases that are preserved in dried films and thus represent ideal templates for novel materials with porous structures and long-range chiral order. The objective of this research project is to systematically investigate the selective-end group modification of cellulose nanocrystals as a means to manipulate their self-assembly into liquid crystal phases, both in colloidal solution and in free-standing films. Accordingly, modification of the ends of CNCs with different crystal structures with a variety of polymer chains is being explored, therefore producing rod-like nanoparticles with asymmetric and symmetric shapes. The liquid crystal properties of the modified CNCs are expected to be more robust and easily controlled in various solvents and in the solid state.

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