Cooper Christopher B, Nikzad Shayla, Yan Hongping, Ochiai Yuto, Lai Jian-Cheng, Yu Zhiao, Chen Gan, Kang Jiheong, Bao Zhenan
Department of Chemical Engineering, Stanford University, Stanford, California 94305, United States.
Stanford Synchroton Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
ACS Cent Sci. 2021 Oct 27;7(10):1657-1667. doi: 10.1021/acscentsci.1c00829. Epub 2021 Sep 8.
Shape memory polymers are promising materials in many emerging applications due to their large extensibility and excellent shape recovery. However, practical application of these polymers is limited by their poor energy densities (up to ∼1 MJ/m). Here, we report an approach to achieve a high energy density, one-way shape memory polymer based on the formation of strain-induced supramolecular nanostructures. As polymer chains align during strain, strong directional dynamic bonds form, creating stable supramolecular nanostructures and trapping stretched chains in a highly elongated state. Upon heating, the dynamic bonds break, and stretched chains contract to their initial disordered state. This mechanism stores large amounts of entropic energy (as high as 19.6 MJ/m or 17.9 J/g), almost six times higher than the best previously reported shape memory polymers while maintaining near 100% shape recovery and fixity. The reported phenomenon of strain-induced supramolecular structures offers a new approach toward achieving high energy density shape memory polymers.
形状记忆聚合物因其具有大的可拉伸性和优异的形状恢复性能，在许多新兴应用中是很有前景的材料。然而，这些聚合物的实际应用受到其低能量密度（高达约1兆焦/立方米）的限制。在此，我们报道了一种基于应变诱导超分子纳米结构的形成来实现高能量密度单向形状记忆聚合物的方法。当聚合物链在应变过程中排列时，会形成强的定向动态键，从而产生稳定的超分子纳米结构，并将拉伸的链捕获在高度伸长的状态。加热时，动态键断裂，拉伸的链收缩至其初始无序状态。这种机制储存了大量的熵能（高达19.6兆焦/立方米或17.9焦/克），几乎是此前报道的最佳形状记忆聚合物的六倍，同时保持接近100%的形状恢复率和固定率。所报道的应变诱导超分子结构现象为实现高能量密度形状记忆聚合物提供了一种新方法。
