Cellulose Nanocrystal Elastomers with Reversible Visible Color. (3rd December 2019)

• Record Type: Journal Article
• Authors: Boott, Charlotte E.; Tran, Andy; Hamad, Wadood Y.; MacLachlan, Mark J.
• Is Part Of: Angewandte Chemie. Volume 132:Number 1(2020)
• Page Start: 232
• Page End: 237
• Publication Date: 2019-12-03
• Subjects: Cellulosenanokristalle -- Helikale Strukturen -- Flüssigkristalle -- Selbstorganisation -- Sichtbare Farbe; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201911468
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: Responsive photonic crystals have potential applications in mechanical sensors and soft displays; however, new materials are constantly desired to provide new innovations and improve on existing technologies. To address this, we report stretchable chiral nematic cellulose nanocrystal (CNC) elastomer composites that exhibit reversible visible color upon the application of mechanical stress. When stretched (or compressed) the colorless materials maintain their chiral nematic structure but the helical pitch is reduced into the visible region, resulting in coloration of the CNC‐elastomer composite. By increasing the percentage elongation of the material (ca. 50–300 %), the structural color can be tuned from red to blue. The color of the materials was characterized by reflectance optical microscopy and reflectance circular dichroism to confirm the wavelength and polarization of the reflected light. We also probed the mechanism of the structural color using 2D‐X‐ray diffraction. Finally, by either water‐patterning the starting CNC film, or by forming a CNC film with gradient color, through masked evaporation, we were able to prepare encoded stretchable chiral nematic CNC‐elastomers. Abstract : Mechanische Spannungssensoren wurden aus Cellulosenanokristall‐Elastomer‐Kompositen hergestellt, die Änderungen der Zugspannung durch eine reversible Farbänderung anzeigen.