Flexible, photonic films of surfactant-functionalized cellulose nanocrystals for pressure and humidity sensing

Fuente: arXiv
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Main Authors: Saraiva, Diogo V., Remiëns, Steven N., Jull, Ethan I. L., Vermaire, Ivo R., Tran, Lisa
Format: Preprint
Published: 2024
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author Saraiva, Diogo V.
Remiëns, Steven N.
Jull, Ethan I. L.
Vermaire, Ivo R.
Tran, Lisa
author_facet Saraiva, Diogo V.
Remiëns, Steven N.
Jull, Ethan I. L.
Vermaire, Ivo R.
Tran, Lisa
contents Most paints contain pigments that absorb light and fade over time. A robust alternative can be found in nature, where structural coloration arises from the interference of light with submicron features. Plant-derived, cellulose nanocrystals (CNCs) mimic these features by self-assembling into a cholesteric liquid crystal that exhibits structural coloration when dried. While much research has been done on CNCs in aqueous solutions, less is known about transferring CNCs to apolar solvents that are widely employed in paints. This study uses a common surfactant in agricultural and industrial products to suspend CNCs in toluene that are then dried into structurally colored films. Surprisingly, a stable liquid crystal phase is formed within hours, even with concentrations of up to 50 wt.-%. Evaporating the apolar CNC suspensions results in photonic films with peak wavelengths ranging from 660 to 920 nm. The resulting flexible films show increased mechanical strength, enabling a blue-shift into the visible spectrum with applied force. The films also act as humidity sensors, with increasing relative humidity yielding a red-shift. With the addition of a single surfactant, CNCs can be made compatible with existing production methods of industrial coatings, while improving the strength and responsiveness of structurally-colored films to external stimuli.
format Preprint
id arxiv_https___arxiv_org_abs_2402_06468
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Flexible, photonic films of surfactant-functionalized cellulose nanocrystals for pressure and humidity sensing
Saraiva, Diogo V.
Remiëns, Steven N.
Jull, Ethan I. L.
Vermaire, Ivo R.
Tran, Lisa
Soft Condensed Matter
Chemical Physics
Optics
Most paints contain pigments that absorb light and fade over time. A robust alternative can be found in nature, where structural coloration arises from the interference of light with submicron features. Plant-derived, cellulose nanocrystals (CNCs) mimic these features by self-assembling into a cholesteric liquid crystal that exhibits structural coloration when dried. While much research has been done on CNCs in aqueous solutions, less is known about transferring CNCs to apolar solvents that are widely employed in paints. This study uses a common surfactant in agricultural and industrial products to suspend CNCs in toluene that are then dried into structurally colored films. Surprisingly, a stable liquid crystal phase is formed within hours, even with concentrations of up to 50 wt.-%. Evaporating the apolar CNC suspensions results in photonic films with peak wavelengths ranging from 660 to 920 nm. The resulting flexible films show increased mechanical strength, enabling a blue-shift into the visible spectrum with applied force. The films also act as humidity sensors, with increasing relative humidity yielding a red-shift. With the addition of a single surfactant, CNCs can be made compatible with existing production methods of industrial coatings, while improving the strength and responsiveness of structurally-colored films to external stimuli.
title Flexible, photonic films of surfactant-functionalized cellulose nanocrystals for pressure and humidity sensing
topic Soft Condensed Matter
Chemical Physics
Optics
url https://arxiv.org/abs/2402.06468