Photonic Hydrogels from Chiral Nematic Mesoporous Chitosan Nanofibril Assemblies

Abstract

Iridescence in animals and plants often arises from structural coloration, which involves hierarchical organization of minerals and biopolymers over length scales of the visible spectrum, leading to diffraction of light. In this work, discarded crustacean shells that are not known for their structural colors are used to produce photonic nanostructures of large, freestanding chiral nematic mesoporous chitosan membranes with tunable iridescent color. Bioinspired by colorful nanostructures in nature, photonic hydrogels with Bouligand‐type organization are fabricated from the twisted mesoporous membranes, where the chitosan nanofibrils are a novel precursor for surface acetylation and are also a biotemplate for polymerizing methyl methacrylate. The colors of the hydrogels can be tailored by swelling as they show large volume changes in response to changes in solvent environment.

Dynamically Controlled Iridescence of Cholesteric Cellulose Nanocrystal Suspensions Using Electric Fields

“…[13][14][15][16][17] These biosourced, lightweight and stiff nanorods, about 100-200 nm long and 5-15 nm in cross-section when extracted from cotton or woodpulp, indeed form stable colloidal suspensions and are able to spontaneously self-organize into cholesteric liquid crystalline phases above a threshold concentration. [18,19] This cholesteric structure is firstly attracting a strong interest as it is generally observed in natural celluloseand chitin-based tissues of plants, [7] crabs [20,21] and insects, [3] where it provides either enhanced mechanical properties such as both stiffness and anti-crack propagation, or optical properties such as structural coloration and iridescence. Secondly, this property of CNCs has been exploited to generate thin solid films displaying adjustable colours [22][23][24][25][26][27] and also led to the development of active mesoporous cellulosic or inorganic photonic sensing materials constructed through nanotemplating strategies.…”

Bioinspired Stimuli‐Responsive Color‐Changing Systems

“…CLC chitosan nanofibrils derived from discarded crustacean exoskeletons and shells have also been employed for the first time to prepare photonic hydrogels . Methyl methacrylate (MMA) monomer is polymerized on the twisted mesoporous chitosan nanofibril template to form PMMA/chitosan composite.…”

Biomimetic Structural Materials: Inspiration from Design and Assembly

“…Nan et al (120) created helicoidal thermal reduced graphene (TRG)/cellulose nanocomposites through a vacuum-assisted self-assembly technique that demonstrate electrical conductivity as well as waterresponsive color changing properties. Nguyen et al (121) used discarded crustacean endocuticles and shells to obtain chitosan nanofibrils and fabricate helicoidal photonic hydrogels.…”