Fractionation of cellulose nanocrystals: enhancing liquid crystal ordering without promoting gelation

Camila Honorato-Rios, Claudius Lehr, Christina Schütz, Roland Sanctuary, Mikhail A. Osipov, Jörg Baller, Jan P. F. Lagerwall

Research output: Contribution to journalArticle

24 Citations (Scopus)
19 Downloads (Pure)

Abstract

Colloids of electrically charged nanorods can spontaneously develop a fluid yet ordered liquid crystal phase, but this ordering competes with a tendency to form a gel of percolating rods. The threshold for ordering is reduced by increasing the rod aspect ratio, but the percolation threshold is also reduced with this change; hence, prediction of the outcome is nontrivial. Here, we show that by establishing the phase behavior of suspensions of cellulose nanocrystals (CNCs) fractionated according to length, an increased aspect ratio can strongly favor liquid crystallinity without necessarily influencing gelation. Gelation is instead triggered by increasing the counterion concentration until the CNCs lose colloidal stability, triggering linear aggregation, which promotes percolation regardless of the original rod aspect ratio. Our results shine new light on the competition between liquid crystal formation and gelation in nanoparticle suspensions and provide a path for enhanced control of CNC self-organization for applications in photonic crystal paper or advanced composites.

Original languageEnglish
Number of pages11
JournalNPG Asia Materials
DOIs
Publication statusPublished - 24 May 2018

Keywords

  • nanocrystals
  • crystallinity
  • gelation

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