Cellulose Nanocrystals for Environment-Friendly Self-Assembled Stimuli Doped Multisensing Photonics

Materials such as cellulose and its derivatives are attracting growing attention worldwide to recognize their potential in responding to increasingly complex technological requirements. The rising demand for multifunctional materials may be fulfilled with controllable functionalities by using self-assembling techniques. Photonic stimuli-responsive materials based on cellulose can shift color reversibly when responding to external inputs. Cellulose nanocrystals (CNCs) are biorenewable materials that self-assemble themselves into a chiral nematic ordering exhibiting iridescent colors. The CNCs display unique optical features in response to environmental stimuli due to the structural coloration mechanism. This review summarizes the CNC-based multisensing photonic structures in response to external dopants. The inclusion of functional polymers, small molecules, or other optically active components into CNC precursors can enhance and stabilize their uniformity, allowing better stimuli interaction with the CNCs. This review reveals that cellulose-based nanomaterials are a potential candidate for designing advanced functional photonics materials in diverse applications for smart textiles, intelligent packaging, security coding, photonic papers, humidity sensors, etc., with some limitations to overcome.