Taking cues from hyper-pigmented reality, scientists are developing a coloration technique that produces vivid iridescent colors using wood pulp – the same stuff that is used to make paper. Researchers from Cambridge University manipulate the wood pulp to rearrange the cellulose within on the nanoscale to change their physical stacking, which in turn changes how they reflect light. The resulting, totally non-toxic film could be used to cover textiles, paper, and other materials that replaces the use of toxic dyes and creates color that would never fade.
Plants get their amazing colors not because their leaves or petals are pigmented, but because their structure, their very being is that color and reflects it when light hits it. Researchers from the University of Cambridge, led by Dr Silvia Vignolini, are looking into how to mimic nature’s own coloration techniques by manipulating structure rather than creating pigments. The researchers took inspiration from the Pollia condensata fruit, which features structural color where the cellulose is stacked together so the ends stick out and reflects light off the ends like glitter. This results in brilliant iridescent and metallic colors, that don’t fade over time. Specimens preserved from the 19th century are still as colorful and shiny as live ones.
Taking this information, the researchers worked to recreate this effect using inexpensive cellulose from wood pulp. They manipulated the wood pulp on the nano scale to rearrange cellulose nanocrystals into a film with specific arrangements. By controlling the humidity during the film fabrication, the scientists can create different colors. While this technique may not be able to create every color of the rainbow, it makes iridescents and metallics with non-toxic wood pulp.
“Nature is a great source of inspiration: we can use biocompatible, cheap and abundant materials for making materials that have applications in everyday life,” said Dr Silvia Vignolini from Cambridge’s Department of Chemistry. “The materials that we produce can be used as substitutes for toxic dyes and colorants in food but also in security labelling or cosmetics.”