Bright cellulose film — an alternative to toxic dyes

Brightly colored films based on cellulose can be a cheap replacement of toxic dyes in textile industry and in the fight against counterfeiting

In nature bright colors are often not the merit of the pigments, and the specific structure of the material. An example is the wings of butterflies, peacock feathers and opals — one of the most colorful objects on the Ground. Researchers from Cambridge University have been able to recreate a similar structure in the laboratory, having a variegated film, which can be used in the textile industry and for authentication of products and documents.





Bright metallic color of the fruit of the Pollia condensata plant due to the spirally stacked cellulose fibers, which reflect light with certain wavelengths. Cellulose can be detected in cells of each plant, this polysaccharide is the most abundant component of biomass on Earth. On the basis of the wood pulp from which paper is made, scientists were able to produce a bright rainbow of a film without the use of pigments.



This requires to extract from wood pulp cellulose nanocrystals. Suspended in water, these nanocrystals are spontaneously joined together in layers, is able to selectively reflect light in a narrow wavelength range. Apparent color of the layer depends on its physical parameters which can be controlled by changing the conditions in which it is formed (in particular, humidity).





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