Photonic Cellulose Films with Vivid Structural Colors: Fabrication and Selectively Chemical Response

Abstract

Recent advances in structural-color cellulose nanocrystal (CNC) materials have been made toward chemical sensing applications; however, such materials lack sufficient color chroma for naked-eye observation, and their selective recognition to given chemicals as well as the corresponding mechanism has rarely been reported. Here, a dopamine-infiltration and post-polymerization approach is proposed to construct vivid structural-color composite films. The chiral nematic structure of CNC enables the structural coloration, while the strong light absorption of the polymeric co-phase, polydopamine (PDA) enhances the color chroma and visibility. By controlling the PDA amount, the composite films can detect organic solvents quantitatively and selectively via visible color changes. From the viewpoint of the compatibility and similitude principle, notably, a critical solubility parameter distance (R 0) between PDA and “active” solvents is defined with a three-dimensional Hansen solubility sphere; this well constructs a rule for the sensing selectivity of the chemochromic composite films. The findings pave the foundation for the design of colorimetric sensors with specifically testing objects.

Biomimetic Chiral Photonic Materials with Tunable Metallic Colorations Prepared from Chiral Melanin-like Nanorods for UV Shielding, Humidity Sensing, and Cosmetics

“…4,8,10,53 We noted that a recent study also tried to address the aforementioned challenges faced by pristine CNC-based photonic films by exploring the light absorption of PDA. 43 However, the authors still followed the conventional doping strategy by preparing CNC-based films at first followed by infiltrating dopamine into the films to form PDA-doped composite photonic films. Herein, using the melanin-like CNC@PDA nanorods with inherent chirality as the only building block, we unify the material economy and chiral optical coloration mechanisms adapted by several biological species to realize chiral photonic materials with brilliant and metallic structural colors, selective reflection of CPLs, and other advanced functions as will be demonstrated later.…”

“…gloriosa and P. condensata, which use additional melanin components for light absorption. ,,, We noted that a recent study also tried to address the aforementioned challenges faced by pristine CNC-based photonic films by exploring the light absorption of PDA . However, the authors still followed the conventional doping strategy by preparing CNC-based films at first followed by infiltrating dopamine into the films to form PDA-doped composite photonic films.…”

“…42 Wang et al recently reported cellulose films with vivid colors by preparing the pristine CNC-based photonic films at first and then infiltrated the films with the light adsorption materials of polydopamine (PDA). 43 In addition to color enhancements, other advanced functions such as UV blocking and humidity-responsive chromatics have also been introduced into the chiral photonic materials of CNCs by incorporating additives with the corresponding functions. However, the functional additives often interfere with the CLC behaviors of the CNC particles and make it even more difficult to address the long-term challenges in preparing CNC-based photonic materials with homogeneous chiral internal structures and therefore well-defined optical properties.…”

“…Instead of such a specific method, incorporation of light absorption materials into photonic materials is a more general strategy. − By doping thermally reduced graphene (TRG) into CNC films, Nan et al imparted certain metallic effects into their hybrid CNC/TRG films . Wang et al recently reported cellulose films with vivid colors by preparing the pristine CNC-based photonic films at first and then infiltrated the films with the light adsorption materials of polydopamine (PDA) . In addition to color enhancements, other advanced functions such as UV blocking and humidity-responsive chromatics have also been introduced into the chiral photonic materials of CNCs by incorporating additives with the corresponding functions.…”

Non-iridescent and Wide-Color-Range Structural Coloration Enabled by Cellulose Nanocrystals with a Controlled Long-Range Photonic Structure and Helical Pitch

“…During the past decade, advances in functional structural color CNC materials have made significant progress. − However, the resulting structural colors exhibit obvious changes depending on viewing angles or incidence angles of light, due to Bragg’s reflection from the periodic structures; this iridescent effect is now regarded as a result of spatial arrangement by kinetic arrest transition upon solvent evaporation . The angle-dependent feature brings great limitations to applications, especially in the fields requiring a wide viewing angle range and constant color display.…”