Integration of Optical Surface Structures with Chiral Nanocellulose for Enhanced Chiroptical Properties

Abstract

The integration of chiral organization with photonic structures found in many living creatures enables unique chiral photonic structures with a combination of selective light reflection, light propagation, and circular dichroism. Inspired by these natural integrated nanostructures, we fabricated hierarchical chiroptical systems that combine imprinted surface optical structures with the natural chiral organization of cellulose nanocrystals. Different periodic photonic surface structures with rich diffraction phenomena, including various optical gratings and microlenses, were replicated into nanocellulose film surfaces over large areas. The resulting films with embedded optical elements exhibit vivid, controllable structural coloration combined with highly asymmetric broadband circular dichroism and a microfocusing capability not typically found in traditional photonic bio-derived materials without compromising their mechanical strength. The strategy of imprinting surface optical structures onto chiral biomaterials facilitates a range of prospective photonic applications, including stereoscopic displays, polarization encoding, chiral polarizers and colorimetric chiral biosensing.

Nanocellulose‐Based Functional Materials: From Chiral Photonics to Soft Actuator and Energy Storage

“…The results provide novel insights into the design and development of bionic photonic cholesteric films. Inspired by the naturally integrated nanostructures, Xiong et al [161] explored the relationship between a 3D chiral assembly and an optical structure by patterning CNC films using different templates (Figure 4e). This new integrated method is significantly superior to the traditional CNC thin-film processing method in terms of the spectral properties of modulated circularly polarized light.…”

Dynamic Chiro‐Optics of Bio‐Inorganic Nanomaterials via Seamless Co‐Assembly of Semiconducting Nanorods and Polysaccharide Nanocrystals

“…CNC dispersions were synthesized from soft-wood pulp via a well-established hydrolysis method (Figure S1, Supporting Information). [39,40] Emissive CdSe/CdS core-shell QNRs were synthesized via a seeded hot injection route. [41] Subsequently, ligand-exchange of as-synthesized QNRs was conducted to replace original hydrophobic surface ligands (a combination of octadecylphosphonic acid and hexylphosphonic acid) with hydrophilic ligands (diaminopropane), yielding water-soluble core-shell QNRs (see Experimental Section).…”

“…Free-standing CNC-QNR composite films were fabricated via evaporation-induced self-assembly process (Figure 2a). [21,39] The resulting films showed a dominant yellow color and excellent mechanical flexibility. A polarized optical microscopy of these films displays birefringence with multiple microscopic LC tactoids (Figure 2b).…”

Orientation Control of Helical Nanofilament Phase and Its Chiroptical Applications

“…Chiral liquid crystal (LC) phases, such as the chiral nematic LC (cholesteric, CLC) phase, the blue phase (BP), and the helical nanofilament (HNF or B4) phase, have been of significant research interest due to the unique helical structures [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. In particular, the structural colors of chiral LC phases have inspired many researchers in the chemistry, physics, and material sciences fields to develop optical and photonic applications, such as various kinds of sensors to detect toxic chemicals or vapors [20][21][22][23][24][25][26].…”