Self-growing photonic composites with programmable colors and mechanical properties.

Many organisms produce stunning optical displays based on structural color instead of pigmentation. This structural or photonic color is achieved through the interaction of light with intricate micro-/nano-structures, which are "grown" from strong, sustainable biological materials such as chitin, keratin, and cellulose. In contrast, current synthetic structural colored materials are usually brittle, inert, and produced via energy-intensive processes, posing significant challenges to their practical uses. Inspired by the brilliantly colored peacock feathers which selectively grow keratin-based photonic structures with different photonic bandgaps, we develop a self-growing photonic composite system in which the photonic bandgaps and hence the coloration can be easily tuned. This is achieved via the selective growth of the polymer matrix with polymerizable compounds as feeding materials in a silica nanosphere-polymer composite system, thus effectively modulating the photonic bandgaps without compromising nanostructural order. Such strategy not only allows the material system to continuously vary its colors and patterns in an on-demand manner, but also endows it with many appealing properties, including flexibility, toughness, self-healing ability, and reshaping capability. As this innovative self-growing method is simple, inexpensive, versatile, and scalable, we foresee its significant potential in meeting many emerging requirements for various applications of structural color materials.

Let it shine: a transparent and photoluminescent foldable nanocellulose/quantum dot paper.

Exploration of environmentally friendly light-emitting devices with extremely low weight has been a trend in recent decades for modern digital technology. Herein, we describe a simple suction filtration method to develop a transparent and photoluminescent nanocellulose (NC) paper, which contains ZnSe quantum dot (QD) with high quantum yield as a functional filler. ZnSe QD can be dispersed uniformly in NC, and a quite low coefficient of thermal expansion is determined for the resultant composite paper, suggesting its good dimensional stability. These results indicate that the meeting of NC with ZnSe QD can bring a brilliant future during the information age.