Photonic Lignin with Tunable and Stimuli-Responsive Structural Color

Abstract

Due to the growing sustainability and health requirements, structural color materials fabricated with functional natural polymers have attracted increasing attention in advanced optical and biomedical fields. Lignin has many attractive features such as great biocompatibility, ultraviolet resistance, antioxidant property, and thermostability, making it a promising natural resource to be fabricated as functional structural color materials. However, to date, the utilization of lignin as the building block for structural color materials is still a challenge due to its disordered structure. Herein, we present a strategy to transform disordered lignin into ordered “photonic lignin”, in which monodisperse lignin colloidal spheres are prepared via solvent/antisolvent self-assembly, and then the periodic structure is constructed by centrifugal effect. The photonic lignin exhibits structural colors that are tunable by modulating the diameter of lignin colloidal spheres. We further demonstrate the application of photonic lignin as a natural polymer-based coating that shows bright, angle-independent, and stimuli-responsive structural colors. Moreover, the cytotoxicity assay indicates the excellent biocompatibility of photonic lignin with human skin, blood vessels, digestive systems, and other tissues, which demonstrates the great potential of photonic lignin in the applications such as implanted/wearable optical devices, advanced cosmetics, and smart food packaging.

Recent progress in low‐swellable polymer‐based smart photonic crystal sensors

“…Readers may refer to some pieces of representative literature. [286][287][288][289][290] Moreover, surface wrinkling can disrupt the original angle dependence by destroying the flat structure of the PC. Using the geometry of the periodic structures of wrinkles, angle-independent structural colors could be obtained in some specific directions (Figure 16d).…”

“…Moreover, quasi‐amorphous arrays are also a class of structural color materials with angle‐independent properties. Readers may refer to some pieces of representative literature [286–290] …”

Binary mixture of subcritical water and acetone: a hybrid solvent system towards the production of lignin nanoparticles

“…10 Furthermore, improved miscibility in water as well as in polymers (i.e., high-density polyethylene 11 ) broadens the application portfolio of lignin, as a drug carrier (i.e., curcumirin 12 ), for adhesives, 13 composites, 14 and coatings. 15 The reaction chemistry to produce LNPs involves predominantly wet chemistry and hydrodynamics-based approaches, which includes pH and solvent shifting, antisolvent precipitation, polymerization (e.g., graft) and spray drying, electrospinning, self-assembly and more. 16,17 Details about these methods can be found elsewhere.…”

Biomimetic intelligent photonic crystal composite films with tri-mode optical states for advanced anti-counterfeiting and information encryption

“…[14][15][16][17] By further incorporating responsive materials, intelligent PCs with adjustable structural colors under external stimuli can be realized, which are expected to offer more variables in anti-counterfeiting. [18][19][20][21][22][23] Although much progress has been made in this area, the single-mode anti-counterfeiting strategy of PCs (i.e., structural color variation) typically confronts imitation risks when using alternatives with similar optical features. 24 Besides, structural colors can only be discerned under visible light, which also hinder their uses under low-/no light conditions.…”