浙江大学谢涛团队报道了具有可编程恢复开始的形状记忆聚合物。相关研究成果于2023年9月13日发表在国际顶尖学术期刊《自然》。

刺激响应型变形聚合物在新兴应用中显示出独特的前景，包括软机器人、医疗设备、航空航天结构和柔性电子。它们的外部触发形状转换行为提供了对许多设备应用至关重要的按需可控性。具有讽刺意味的是，在现实场景下获得外部触发器（例如加热或光）已成为植入式医疗设备等高要求应用的最大瓶颈。某些形状变化聚合物依赖于自然存在的刺激（例如，可植入设备的人体温度）作为触发因素。尽管他们放弃了对外部刺激的需求，但控制恢复发作的能力也丧失了。自然触发但主动可控的变形行为是非常可取的，但这两个属性是相互冲突的。

该文中，研究人员用一种四维可打印的形状记忆水凝胶实现了这一目标，该水凝胶通过相分离操作，其形状移动动力学由内部质量扩散而非常见形状记忆聚合物的热传输控制。这种水凝胶可以在自然环境温度下发生形状转变，关键是恢复开始延迟。这种延迟可以通过在组分编辑期间改变相分离的程度来编辑，这为形状移动控制提供了一种独特的机制。该自然触发形状记忆聚合物具有可调的恢复开始，显著降低了设备实现的障碍。

该自然触发形状记忆聚合物具有可调的恢复开始，显著降低了设备实现的障碍。

附：英文原文

Title: Shape memory polymer with programmable recovery onset

Author: Ni, Chujun, Chen, Di, Yin, Yu, Wen, Xin, Chen, Xiaolan, Yang, Chen, Chen, Guancong, Sun, Zhuo, Wen, Jihang, Jiao, Yurong, Wang, Chunyang, Wang, Ning, Kong, Xiangxing, Deng, Shihong, Shen, Youqing, Xiao, Rui, Jin, Xiuming, Li, Jun, Kong, Xueqian, Zhao, Qian, Xie, Tao

Issue&Volume: 2023-09-13

Abstract: Stimulus-responsive shape-shifting polymers1–3 have shown unique promise in emerging applications, including soft robotics4–7, medical devices8, aerospace structures9 and flexible electronics10. Their externally triggered shape-shifting behaviour offers on-demand controllability essential for many device applications. Ironically, accessing external triggers (for example, heating or light) under realistic scenarios has become the greatest bottleneck in demanding applications such as implantable medical devices8. Certain shape-shifting polymers rely on naturally present stimuli (for example, human body temperature for implantable devices)8 as triggers. Although they forgo the need for external stimulation, the ability to control recovery onset is also lost. Naturally triggered, yet actively controllable, shape-shifting behaviour is highly desirable but these two attributes are conflicting. Here we achieved this goal with a four-dimensional printable shape memory hydrogel that operates via phase separation, with its shape-shifting kinetics dominated by internal mass diffusion rather than by heat transport used for common shape memory polymers8–11. This hydrogel can undergo shape transformation at natural ambient temperature, critically with a recovery onset delay. This delay is programmable by altering the degree of phase separation during device programming, which offers a unique mechanism for shape-shifting control. Our naturally triggered shape memory polymer with a tunable recovery onset markedly lowers the barrier for device implementation. A four-dimensional printable shape memory hydrogel with shape-shifting onset adjustable by changing the programming conditions is reported.

DOI: 10.1038/s41586-023-06520-8

Source: https://www.nature.com/articles/s41586-023-06520-8