Influence of the particle concentration and marangoni flow on the formation of cellulose nanocrystal films

Alican Gençer, Christina Schütz, Wim Thielemans

Research output: Contribution to journalArticlepeer-review

98 Citations (SciVal)

Abstract

Cellulose nanocrystals (CNCs), ribbonlike crystalline nanoparticles, are a biobased material that can be a great alternative to obtaining films with tunable optical properties. Iridescent and light-diffracting films can be readily obtained via the drying of a suspension of these cellulose nanocrystals. The characteristics of the particle deposition process together with the self-Assembly in the precluding suspension has a direct effect on the optical properties of the obtained films. Particle deposition onto a substrate is affected by the flow dynamics inside sessile droplets and usually yields a ringshaped deposition pattern commonly referred to as the coffee-ring effect. We set out to measure and describe the drying kinetics under different conditions. We found that the Marangoni flow inside the droplet was too small to counteract the capillary flow that deposits CNCs at the edges, resulting in the coffee-ring effect, irrespective of the atmospheric humidity. By varying the amount of ethanol in the atmosphere, we were able to find a balance between (1) colloidal stability in the droplet, which is reduced by ethanol diffusion into the droplet, and (2) increasing Marangoni flow relative to capillary flow inside the droplet by changing the droplet surface tension. We could thus make iridescent films with a uniform thickness.

Original languageEnglish
Pages (from-to)228-234
Number of pages7
JournalLangmuir
Volume33
Issue number1
DOIs
Publication statusPublished - 10 Jan 2017

Bibliographical note

Funding Information:
The authors thank Research FoundationFlanders (FWO) for funding under the Odysseus grant (G.0C60.13N) and KU Leuven for grant OT/14/072. W.T. also thanks the Provincie West-Vlaanderen (Belgium) for financial support through his Provincial Chair in Advanced Materials.

Publisher Copyright:
© 2016 American Chemical Society.

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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