, Volume 22, Issue 2, pp 1103–1107 | Cite as

Droplets of cellulose nanocrystal suspensions on drying give iridescent 3-D “coffee-stain” rings

Original Paper


Films prepared from aqueous suspensions of cellulose nanocrystals (CNC) often display iridescent colors due to the reflection of light from the helicoidal orientation of the rod-like CNC in the film. Droplets of CNC suspension deposited on a plane surface evaporate to give films that display iridescent rings. Profilometry measurements across the rings show that the outer edge of the films is much thicker than the region in the center. This is ascribed to a “coffee-stain” effect; the CNC are transported to the outer edge for droplets where the contact line is pinned during evaporation. The gradient in concentration across the ring results in a color gradient, with the longer wavelengths decreasing towards the center of the sample, in accord with the hypothesis of a two-stage process for CNC chiral nematic color formation.


Cellulose nanocrystals Iridescent films Chiral nematic structure Coffee-stain effect Film topology and color 



We thank Dr. Tiffany Abitbol for preparation of the CNC suspension, and Dr. H.P.T. Nguyen and the McGill Nanotools Microfab facility for the profilometry measurements. Funding from the Natural Sciences and Engineering Research Council Canada, and support from Fonds Québecois de la Recherche sur la Nature et les Technologies through the Center for Self-Assembled Chemical Structures is gratefully acknowledged.


  1. Beck S, Bouchard J, Berry R (2011) Controlling the reflection wavelength of iridescent solid films of nanocrystalline cellulose. Biomacromolecules 12(1):167–172CrossRefGoogle Scholar
  2. Beck S, Méthot M, Bouchard J (2014) General procedure for determining cellulose nanocrystals sulfate half-ester content by conductometric titration. Cellulose. doi: 10.1007/s10570-014-0513-y Google Scholar
  3. Deegan RD, Bakajin O, Dupont TF, Huber G, Nagel SR, Witten TA (1997) Capillary flow as the cause of ring stains from dried liquid drops. Nature 389:827–829CrossRefGoogle Scholar
  4. Dugyala VR, Daware SV, Basavaraj MG (2013) Shape anisotropic colloids: synthesis, packing behavior, evaporation driven assembly, and their application in emulsion stabilization. Soft Matter 9(29):6711–6725CrossRefGoogle Scholar
  5. Dumanli AG, van der Kooij HM, Kamita G, Reisner E, Baumberg JJ, Steiner U, Vignolini S (2014) Digital color in cellulose nanocrystal films. ACS Appl Mater Interfaces 6(15):12302–12306CrossRefGoogle Scholar
  6. Lagerwall JPF, Schütz C, Salajkova M, Noh JH, Park JH, Scalia G, Bergström L (2014) Cellulose nanocrystalbased materials: from liquid crystal self-assembly and glass formation to multifunctional thin films. NPG Asia Mater 6(1):e80Google Scholar
  7. Mu X, Gray DG (2014) Formation of chiral nematic films from cellulose nanocrystal suspensions is a two-stage process. Langmuir 30(31):9256–9260CrossRefGoogle Scholar
  8. Nobile C, Carbone L, Fiore A, Cingolani R, Manna L, Krahne R (2009) Self-assembly of highly fluorescent semiconductor nanorods into large scale smectic liquid crystal structures by coffee stain evaporation dynamics. J Phys Condens Matter 21(26):264013–264017CrossRefGoogle Scholar
  9. Onsager L (1949) The effects of shape on the interaction of colloidal particles. Ann NY Acad Sci 51(2):627–659CrossRefGoogle Scholar
  10. Querner C, Fischbein MD, Heiney PA, Drndić M (2008) Millimeter-scale assembly of CdSe nanorods into smectic superstructures by solvent drying kinetics. Adv Mater 20(12):2308–2314CrossRefGoogle Scholar
  11. Revol J-F, Godbout L, Gray DG (1998) Solid films of cellulose with chiral nematic order and optically variable properties. J Pulp Pap Sci 24(5):146–149Google Scholar

Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  1. 1.Department of ChemistryMcGill UniversityMontrealCanada

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