For designing water-soluble responsive materials, utilizing crown ethers as main building blocks has been rarely explored in contrast to their linear poly(ethylene glycol) counterparts. In the current study, we report the robust thermoresponsive properties of the benzo-21-crown-7 (B21C7) family with lower critical solution temperature (LCST) and upper critical solution temperature (UCST) behavior. Different substituent groups on the benzene ring exhibit significant effects on water solubility and thermoresponsiveness. B21C7 and its cyano derivative display LCST phenomena, while B21C7-based carboxylic acid derivative presents UCST followed by LCST phase behavior. Supramolecular interactions with KCl provide an additional tuning approach for this crown ether system. These results demonstrate that B21C7s can serve as an easily accessible toolbox to develop new thermosensitive systems and prepare thermally responsive materials.

中文翻译：

---

Benzo-21-crown-7及其衍生物的热敏相行为

在设计水溶性响应材料时，与其冠状线性聚（乙二醇）相比，很少使用冠醚作为主要结构单元。在当前的研究中，我们报告了具有较低临界溶液温度（LCST）和较高临界溶液温度（UCST）行为的苯并21冠7（B21C7）系列的强大热响应特性。苯环上的不同取代基对水溶性和热响应性具有显着影响。B21C7及其氰基衍生物显示LCST现象，而B21C7基羧酸衍生物呈现UCST，随后呈现LCST相行为。与KCl的超分子相互作用为这种冠醚系统提供了另一种调节方法。这些结果表明，B21C7可以用作开发新的热敏系统和制备热响应材料的便捷工具箱。