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Controlling the self-assembly of cellulose nanocrystals using external fields and confinement - Bruno Frka-Petesic

Dept. of Chemistry, University of Cambridge, UK.

Amphi Blandin

Cellulose nanocrystals (CNCs) are bio-sourced chiral nanorods that can form colloidal suspensions either in water or apolar solvents. Above a critical concentration, they spontaneously self-assemble into a cholesteric liquid crystalline phase. These suspensions are iridescent when observed in transmission, whereas, when cast on a substrate, they assemble into solid-state films that retain a cholesteric order, which causes strong reflection of specific wavelengths in the visible range.
I will first discuss how we can use the complementary orientational coupling of individual CNCs with external electric or magnetic fields to control the self-assembly over larger length scales, both in suspensions and in dry films. I will then illustrate how the confinement geometry during the evaporation process affects the final structure and the resulting optical response when assembled either in microfluidic droplets, sessile droplets or in macroscopic dishes.

References :
[1] R. M. Parker, B. Frka-Petesic et al., ACS Nano 2016, 10, 8443.
[2] B. Frka-Petesic et al., Adv. Mater. 2017, 29, 1606208.
[3] B. Frka-Petesic et al., Adv. Mater. 2017, 29, 1701469.
[4] R. M. Parker, B. Frka-Petesic et al., Adv. Mater. 2018, 30, 1704477.
[5] T. H. Zhao et al. Adv. Funct. Mater. 2018, 1804531.