Complex Materials, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland.
Soft Matter. 2014 Mar 7;10(9):1284-94. doi: 10.1039/c3sm51883c.
Nature displays numerous examples of materials that can autonomously change their shape in response to external stimuli. Remarkably, shape changes in biological systems can be programmed within the material's microstructure to enable self-shaping capabilities even in the absence of cellular control. Here, we revisit recent attempts to replicate in synthetic materials the shape-changing behavior of selected natural materials displaying deliberately tuned fibrous architectures. Simple processing methods like drawing, spinning or casting under magnetic fields are shown to be effective in mimicking the orientation and spatial distribution of reinforcing fibers of natural materials, thus enabling unique shape-changing features in synthetic systems. The bioinspired design and creation of self-shaping microstructures represent a new pathway to program shape changes in synthetic materials. In contrast to shape-memory polymers and metallic alloys, the self-shaping capabilities in these bioinspired materials originate at the microstructural level rather than the molecular scale. This enables the creation of programmable shape changes using building blocks that would otherwise not display the intrinsic molecular/atomic phase transitions required in conventional shape-memory materials.
自然界展示了许多能够自动响应外部刺激改变形状的材料实例。值得注意的是，生物系统中的形状变化可以在材料的微观结构中进行编程，即使没有细胞控制，也能实现自成型能力。在这里，我们重新审视了最近在合成材料中复制具有刻意调谐纤维结构的选定天然材料的形状变化行为的尝试。简单的处理方法，如在磁场下拉制、纺丝或浇铸，被证明可以有效地模仿天然材料增强纤维的取向和空间分布，从而在合成系统中实现独特的形状变化特征。仿生设计和自成型微结构的创建代表了在合成材料中编程形状变化的新途径。与形状记忆聚合物和金属合金相比，这些仿生材料的自成型能力源于微观结构层面，而不是分子尺度。这使得使用原本不会显示传统形状记忆材料所需的固有分子/原子相变的构建块来创建可编程的形状变化成为可能。
