Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China.
ACS Macro Lett. 2023 Jul 18;12(7):835-840. doi: 10.1021/acsmacrolett.3c00239. Epub 2023 Jun 9.
Tunable multishape memory polymers offer intriguing opportunities for memorizing multiple temporary shapes with tunable transition temperatures from one material composition. However, such multishape memory effects have been exclusively correlated with the thermomechanical behaviors of polymers, significantly limiting their applications in heat-sensitive scenarios. Here we report a nonthermal tunable multishape memory effect in covalently cross-linked cellulosic macromolecular networks, which spontaneously organize into supramolecular mesophases by water evaporation induced self-assembly. The supramolecular mesophase endows the network with a broad, reversible hygromechanical response combined with a unique moisture memory effect at ambient temperature, enabling diverse multishape memory behaviors (dual-, triple-, and quadruple-shape memory) under highly tunable and independent control of relative humidity (RH) alone. Significantly, such a hygroscopic tunable multishape memory effect readily extends the implications of shape memory polymers beyond the conventional thermomechanical regimes with potential advantages for biomedical applications.
可调多形状记忆聚合物提供了有趣的机会，可以用可调转变温度从一种材料组成记忆多个临时形状。然而，这种多形状记忆效应仅与聚合物的热机械行为相关，极大地限制了它们在热敏场景中的应用。在这里，我们报告了在共价交联纤维素高分子网络中存在非热可调多形状记忆效应，这是通过水蒸发诱导自组装而自发形成的超分子中间相。超分子中间相赋予网络广泛的、可逆的湿度机械响应，以及在环境温度下的独特的湿度记忆效应，使得在高度可调且仅单独控制相对湿度的情况下，可以实现多种多形状记忆行为（双形状、三形状和四形状记忆）。重要的是，这种吸湿可调多形状记忆效应很容易将形状记忆聚合物的应用扩展到传统的热机械范围之外，为生物医学应用带来了潜在的优势。
