Bio-inspired iridescent layer-by-layer assembled cellulose nanocrystal Bragg stacks

Layer-by-layer (LbL) assembly was used to fabricate a synthetic analogue of the color producing multilayered structure commonly found in many biological systems, particularly Coleoptera. The resulting iridescent films comprise multiple LbL-deposited layers designed to control color appearance through the materials' refractive indices and individual multilayer layer thicknesses. The fabricated systems, referred to as Bragg stacks, exhibited very similar optical behavior to the model and the beetle, selectively reflecting the desired color in a narrow band of visible wavelengths and displaying iridescent behavior.