Printing Flowers? Custom-tailored Photonic Cellulose Films with Engineered Surface Topography

TL;DR

This paper presents a scalable method to create custom photonic cellulose films with engineered surface topography, combining cholesteric organization and microscopic wrinkles for tunable optical properties and patterned imaging.

Contribution

It introduces a novel nanoimprinting technique to fabricate cellulose films with controlled surface wrinkles and cholesteric order, enabling advanced photonic functionalities.

Findings

Achieved morphology-induced light scattering at short wavelengths.

Demonstrated optically tunable structural color.

Enabled precise patterning of microscopic images.

Abstract

Wrought by nature's wondrous hand, surface topographies are discovered on all length scales in living creatures and serve a variety of functions. Inspired by floral striations, here we developed a scalable means of fabricating custom-tailored photonic cellulose films that contained both cholesteric organization and microscopic wrinkly surface topography. Free-standing films were prepared by molding cellulose nanocrystal ink onto an oriented wrinkled template through evaporation-assisted nanoimprinting lithography, yielding morphology-induced light scattering at a short wavelength as well as optically tunable structural color derived from the helical cellulose matrix. As a result, the interplay between the two photonic structures, grating-like surface and chiral bulk, led to selective scattering of circularly polarized light with specific handedness. Moreover, the wrinkled surface relief on cholesteric cellulose films could be precisely controlled, enabling engineered printing of microscopic patterned images.