Strong, tough, and stiff nanocellulose photonic laminates with customized optical functions

Construction of strong, tough, and stiff biophotonic materials with customized and extended optical performance is significant to expand sustainable optics while it remains challenging. Herein, we propose a vacuum-assisted layer-by-layer assembly of cellulose nanocrystal and cellulose nanofiber alternatingly to fabricate nanocellulose photonic laminates. This strategy leverages the vacuum-assisted self-assembly (VASA) technique to regulate drying kinetics and the layer-by-layer method to harmlessly incorporate energy-dissipating phases, enabling the fabrication of homogeneous and densely-packed nanocellulose photonic laminates with finely- tailored optomechanical performances. Specifically, the resultant nanocellulose photonic laminates synergistically integrate load-bearing cellulose nanocrystal sublayers and energy-dissipating cellulose nanofiber sublayers, achieving a comprehensive combination of high strength, toughness, stiffness, and impact resistance. Moreover, the resulting nanocellulose photonic laminates demonstrate well controllability and flexible editability in stacking structure via layer-by-layer assembly variation, that enables versatile optical functionalities, including arbitrary color blending based on the RGB color model and machine-learning-assisted color prediction. Impressively, by integrating nanocellulose photonic laminates with diverse stacked architectures, we establish a photonic matrix platform featuring programmable color-switching responses for information encoding and encryption. This work takes a crucial step forward to sustainable photonic materials with excellent mechanical combinations and optical functionality for bio-enabled display technologies and security indicators.