Miao Tengfei, Cheng Xiaoxiao, Zhang Gong, Wang Yuqing, He Zixiang, Wang Zhao, Zhang Wei
State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, Jiangsu Engineering Laboratory of Novel Functional Polymeric Materials, Suzhou Key Laboratory of Macromolecular Design and Precision Synthesis, College of Chemistry, Chemical Engineering and Materials Science, Soochow University Suzhou 215123 Jiangsu China
Jiangsu Key Laboratory for Chemistry of Low-Dimensional Materials, School of Chemistry and Chemical Engineering, Huaiyin Normal University Huaian 223300 Jiangsu China
Chem Sci. 2023 Jan 10;14(7):1673-1678. doi: 10.1039/d2sc05975d. eCollection 2023 Feb 15.
Macroscopic regulation of chiral supramolecular nanostructures in liquid-crystalline block copolymers is of great significance in photonics and nanotechnology. Although fabricating helical phase structures chiral doping and microphase separation has been widely reported, the chiral memory and self-recovery capacity of asymmetric phase structures are the major challenge and still deeply rely on the presence of chiral additives. Herein, we demonstrate the first controllable chiral microphase separation in an achiral amphiphilic block copolymer consisting of poly(ethylene oxide) and azobenzene (Azo) groups. Chirality can be transferred to the fabricated helical nanostructures by doping with chiral additives (tartaric acid, TA). After the removal of the chiral additives and then performing cross-linking, the formed helical nanostructures will completely dispense with the chiral source. The supramolecular chirality and the micron-scale phase structure can be maintained under UV irradiation and heating-cooling treatment, enabling a reversible "on-off" chiroptical switch feature. This work is expected to avoid the tedious synthesis and expensive raw materials and shows a great application prospect in chiral separation and so on.
液晶嵌段共聚物中手性超分子纳米结构的宏观调控在光子学和纳米技术中具有重要意义。尽管通过手性掺杂和微相分离制备螺旋相结构已被广泛报道，但不对称相结构的手性记忆和自恢复能力是主要挑战，并且仍然严重依赖手性添加剂的存在。在此，我们展示了在由聚环氧乙烷和偶氮苯（Azo）基团组成的非手性两亲嵌段共聚物中首次实现可控的手性微相分离。通过掺杂手性添加剂（酒石酸，TA），手性可以转移到所制备的螺旋纳米结构中。去除手性添加剂然后进行交联后，形成的螺旋纳米结构将完全摆脱手性源。超分子手性和微米级相结构在紫外线照射和加热-冷却处理下可以保持，实现可逆的“开-关”手性光学开关特性。这项工作有望避免繁琐的合成和昂贵的原材料，并在手性分离等方面展现出巨大的应用前景。
