Dynamics of Hydration of Nanocellulose Films

Paolo Bettotti, Cecilia Ada Maestri, Romain Guider, Ines Mancini, Einat Nativ-Roth, Yuval Golan, Marina Scarpa

Research output: Contribution to journalArticlepeer-review

21 Scopus citations

Abstract

The design of materials capable of mechanical responses to physical and chemical stimuli represents one of the most exciting and challenging areas of scientific research because of the huge number of their potential applications. This article is focused on the molecular events occurring in thin films of carboxylated nanocellulose fibers, which are capable of converting water gradients into mechanical movements at the macroscopic scale. The analysis of the mechano-actuation, and of the conditions to obtain it, shows that the film movement is fast and reproducible, the gradient intensity is transduced into rate of displacement, and the response is observed at vapor pressures as low as 1.2 mm Hg. The actuation mechanism is associated to an efficient and reversible water sorption process by the hydrophilic nanocellulose fibers at the film interface. Conversely, water desorption is slow and follows a kinetic behavior supporting the presence of two binding sites for water molecules. The adsorbed water induces swelling of the surface nanocellulose layers and local structural rearrangement, however transitions between ordered and random coil conformations are not observed. The understanding of the actuation mechanisms of nanocellulose offers exciting opportunities to design macroscopic structures responding to chemical gradients by the assembly of simple molecular components.

Original languageEnglish
Article number1500415
JournalAdvanced Materials Interfaces
Volume3
Issue number5
DOIs
StatePublished - 7 Mar 2016

Keywords

  • actuators
  • hydration
  • nanocellulose
  • stimuli-responsive films
  • water gradients

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