Bingbing Cui,Chuanpan Guo,Zhihong Zhang,Guodong Fu
Photochromic hydrogels, which are dynamic in response to external light stimuli, have aroused increasing attentions due to their potential applications in intelligent devices. However, achieving excellent photochromic activity with fast photoresponse and self-bleaching rates still remains a huge challenge. Herein, a novel photochromic junction of zinc-based metal–organic framework (Zn-MOF) and tungsten oxide (WO 3 ) was established as photochromic unit and embraced within hydrogel of poly(acrylic acid- co -polyethylene glycol) [P(AA/PEG)] via the interaction of ionic and hydrogen bonding (denoted as P(AA/PEG)-Zn-MOF@WO 3 ), following by exploiting as self-bleaching photochromic agent for assembling UV-irradiated smart rewritable device. The photoinduced electrons can be efficiently separated and migrated from Zn-MOF to WO 3 in the Zn-MOF@WO 3 junction after UV irradiation, thereby increasing the coloration degree. Due to the enhanced fast response to light stimuli, the P(AA/PEG)-Zn-MOF@WO 3 -3 hydrogel prepared using 200 mg Zn-MOF demonstrated the fast responsive photochromic behavior of 10 s under UV lamp illumination and the self-fading process could be easily performed in room condition (within 20 min). Moreover, the coloration degree of P(AA/PEG)-Zn-MOF@WO 3 -3 photochromic hydrogel was precisely controlled and repeated by changing the UV irradiation time. Consequently, the fast photochromic and self-fading properties of P(AA/PEG)-Zn-MOF@WO 3 -3 afforded rapid and easy ‘‘writing’’ and “erasing” abilities. The present work proposes a new way for the construction of the reversibly responsive photochromic hydrogel with smart optical materials, further broadening their applications in intelligence sensors, smart windows, and flexible memory devices.
Ning Ding,Neng Hu,Junfeng Zhang,Huawei Xu,Liubang Meng,Xin Cai,Peter Müller-Buschbaum,Dongming Qi,Qi Zhong
Because of the detrimental effects of excessive exposure to solar ultraviolet radiation (UVR) on human skin health, wearable UVR detectors have attracted more and more attention. Inspired by the artwork “Tian-tsui hair pin with flora decoration” from the Palace Museum, a reversible and photochromic peony-shaped hairpin is designed to realize the visualized detection of solar UV radiation. It is prepared via electrospinning a mixed solution containing thermoplastic polyurethanes (TPUs) and Zn-MOF@WO3 onto microfiber nonwoven fabrics (MFNFs). Because of the enhanced UV responsive and photochromic capability from Zn-MOF@WO3 as well the excellent flexibility from TPUs and MFNFs, the obtained hairpin presents an excellent photoresponsive and wearable performance. When exposed to UV radiation from sunshine, the hairpin switches from white to light blue and finally to blue with radiation time. The colors light blue and blue can be used to indicate the UV radiation doses for the synthesis of vitamin D and the induction of erythema, respectively. With the assistance of oxygen in air, the hairpin recovers to its original state after being maintained in a dark atmosphere for 12 h. Even after six cycles of exposure to UV radiation and recovery in the dark, the photochromic performance almost remains unchanged. Only a minor reduction of 5% is observed. As a traditional wearable headdress in China, the peony-shaped hairpin prepared from the hybrid nanofibers not only presents oriental elegance but also is suitable for cyclical use in the daytime to monitor UV radiation for skin health management.
危险品化学品经营许可证（带存储）