Colloidally Stable Monolayer Nanosheets with Colorimetric Responses

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2019-02, Vol.15 (5), p.e1804975-n/a
• Main Authors: Hu, Bojian, Sun, Shengtong, Wu, Baohu, Wu, Peiyi
• Format: Article
• Language: English
• Subjects: Aqueous solutions; Chemical synthesis; colloidal stablility; Colloids; colorimetric responses; Colorimetry; Hybrid systems; Infrared radiation; Inkjet printing; Lateral stability; Layered materials; Micrometers; monolayer nanosheets; Monolayers; Nanomaterials; Nanosheets; Nanotechnology; polydiacetylene; Polydiacetylenes; Thermochromism; Vacuum filtration
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201804975

Despite the discovery of chromogenic‐layered materials for decades of years, fabrication of colloidally stable monolayer organic 2D nanosheets in aqueous media with colorimetric responses is still challenging. Herein reported is the first solution synthesis of chromic monolayer nanosheets via the topochemical polymerization of self‐assembled amphiphilic diacetylenes in aqueous media. The polydiacetylene (PDA) nanosheets are ≈3–4 nm thick in solution and only ≈1.9 nm thick in the dried state, while the lateral size can reach several micrometers. Moreover, the aqueous stability endows PDA nanosheets with excellent processability, which can further assemble into films via vacuum filtration or act as an ink for high‐resolution inkjet printing. The filtrated films and printed patterns exhibit fully reversible blue‐to‐red thermochromism, and the film also displays an interesting reversible colorimetric transition in response to near‐infrared light, which is not reported for other PDA‐only systems. The present colloidal PDA nanosheets should represent a new kind of chromic organic 2D nanomaterials that may be applied as novel building blocks for developing intelligent hybrid materials and may also find diverse sensing, display and/or anticounterfeiting applications. An example of colloidally dispersed monolayer chromic polydiacetylene (PDA) nanosheets with large lateral sizes and long‐term aqueous stability is reported. The monolayer PDA nanosheets can be easily processed into films via vacuum filtration or high‐resolution patterns via inkjet printing that can exhibit reversible blue‐to‐red chromism in response to heat and/or near‐infrared light.