Department of Chemistry, University of British Columbia, 2036 Mail Mall, Vancouver, BC, V6T 1Z1, Canada.
Stewart Blusson Quantum Matter Institute, 2355 East Mall, Vancouver, BC, V6T 1Z4, Canada.
Adv Mater. 2020 Oct;32(41):e1905876. doi: 10.1002/adma.201905876. Epub 2020 Feb 3.
Over millions of years, animals and plants have evolved complex molecules and structures that endow them with vibrant colors. Among the sources of natural coloration, structural color is prominent in insects, bird feathers, snake skin, plants, and other organisms, where the color arises from the interaction of light with nanoscale features rather than absorption from a pigment. Cellulose nanocrystals (CNCs) are a biorenewable resource that spontaneously organize into chiral nematic liquid crystals having a hierarchical structure that resembles the Bouligand structure of arthropod shells. The periodic, chiral nematic organization of CNC films leads them to diffract light, making them appear iridescent. Over the past two decades, there have been many advances to develop the photonic properties of CNCs for applications ranging from cosmetics to sensors. Here, the origin of color in CNCs, the control of photonic properties of CNC films, the development of new composite materials of CNCs that can yield flexible photonic structures, and the future challenges in this field are discussed. In particular, recent efforts to make flexible photonic materials using CNCs are highlighted.
在数百万年的时间里，动物和植物已经进化出复杂的分子和结构，赋予它们鲜艳的颜色。在天然色彩的来源中，结构色在昆虫、鸟类羽毛、蛇皮、植物和其他生物体中尤为突出，其颜色源于光与纳米级特征的相互作用，而不是来自于色素的吸收。纤维素纳米晶体（CNC）是一种可再生资源，它会自发地组织成具有类似于节肢动物贝壳的布利冈结构的手性向列液晶。CNC 薄膜的周期性、手性向列组织导致它们对光产生衍射，使它们呈现出虹彩效果。在过去的二十年中，人们在开发从化妆品到传感器等应用的 CNC 光子特性方面取得了许多进展。本文讨论了 CNC 产生颜色的原因、控制 CNC 薄膜的光子特性、开发可产生柔性光子结构的新型 CNC 复合材料，以及该领域未来的挑战。特别是，本文强调了最近利用 CNC 制造柔性光子材料的努力。
