State Key Laboratory of Fine Chemicals, Dalian University of Technology, 2# Linggong Road, Dalian 116024, P.R. China.
ACS Nano. 2021 Oct 26;15(10):15720-15729. doi: 10.1021/acsnano.1c05612. Epub 2021 Sep 14.
Both the nonclose-packed structure and the large refractive index contrast of guanine nanocrystals and cytosols in iridophores play a vital role in the dynamic camouflage of chameleons, including the bright skin color and color tuning sensitivity to external stimulus. Here, the nonclose-packed photonic crystals consisting of ZnS nanospheres and polymers, which have similar refractive indices with guanine nanocrystals and cytosols, respectively, are constructed by a two-step filling strategy. ZnS@SiO nanospheres are self-assembled to build intermediate close-packed photonic crystals followed by filling polymers in their interstices. The nonclose-packed photonic crystal is successfully achieved when the silica portion is etched by HF solution and refilled by polymers. Excitingly, the stimulus response of the designed photonic crystal is as sensitive as the skin of chameleons due to the similar contrast of refractive indices and nonclose-packed structure. The reflection peak of the structure can blue-shift more than 200 nm as the temperature increases from 30 to 55 °C or under 20% compressional strain. This work not only builds the nonclose-packed photonic crystals by introducing a two-step filling strategy but also proves that high refractive contrast in photonic crystals is an effective strategy to achieve ultrasensitivity, which is highly desirable for various applications.
非密堆积结构和嘌呤纳米晶体及细胞液的大折射指数对比在变色龙的动态伪装中起着至关重要的作用，包括变色龙明亮的皮肤颜色和对外界刺激的颜色调谐敏感性。在这里，由两步填充策略构建了由 ZnS 纳米球和聚合物组成的具有类似的折射指数与嘌呤纳米晶体和细胞液的非密堆积光子晶体。ZnS@SiO 纳米球自组装形成中间密堆积光子晶体，然后在它们的间隙中填充聚合物。当 HF 溶液刻蚀二氧化硅部分并由聚合物重新填充时，成功实现了非密堆积光子晶体。令人兴奋的是，由于折射率对比和非密堆积结构的相似性，设计的光子晶体的刺激响应与变色龙的皮肤一样敏感。当温度从 30°C 升高到 55°C 或在 20%压缩应变下时，结构的反射峰可以蓝移超过 200nm。这项工作不仅通过引入两步填充策略构建了非密堆积光子晶体，还证明了光子晶体中的高折射对比度是实现超灵敏度的有效策略，这对于各种应用非常理想。
