An easy way to pattern the surface of cellulose so that it forms a colourful photonic crystal has been developed.
As society looks for sustainable and eco-friendly alternatives to common plastics, cellulose is attracting increasing interest. The planet’s most abundant biopolymer, cellulose is readily available, cheap and biodegradable. It can also be processed into cellulose nanoparticles, which have many applications.
Although cellulose typically scatters light diffusely — the property that makes paper white — nanocellulose can incorporate microstructural features that interact with light to give it colour. Structural colour also gives some butterfly wings their iridescence, for example.
Researchers from the Spanish National Research Council (ICMAB-CSIC) have shown that a technology called soft nanoimprinting lithography can easily create these features in a cellulose derivative. The team could stamp a submicrometre scale pattern onto a hot hydroxypropyl cellulose surface, forming free-standing photonic crystals that produce a rainbow of colours.
The crystals could be used for various photonic and plasmonic applications.
© Wolfgang Kaehler/Getty
Nature Photonics 12, 343–348 (2018). DOI: 10.1038/s41566-018-0152-1
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