Three-dimensional printing of hierarchical liquid-crystal-polymer structures
Three-dimensional printing of hierarchical liquid-crystal-polymer structures
复制标题
DOI：
10.1038/s41586-018-0474-7
复制
发表时间：
2018-09-13
期刊：
影响因子：
64.8
通讯作者：
Studart, Andre R.
中科院分区：
文献类型：
--
作者：
Gantenbein, Silvan;Masania, Kunal;Studart, Andre R.
纤维增强聚合物结构通常用于需要刚性轻质材料的场合，例如飞机、车辆和生物医学植入物。尽管它们具有非常高的刚度和强度（1），但这种轻质材料需要能源和劳动密集型的制造工艺（2），通常表现出脆性断裂，并且难以成形和回收（3，4）。这与轻质生物材料形成鲜明对比，如骨骼，丝绸和木材，它们通过定向自组装形成具有出色机械性能的复杂，分层结构的形状（5-11），并循环融入环境。在这里，我们展示了一种三维（3D）打印方法，可以生成具有分层结构、复杂几何形状和前所未有的刚度和韧性的可回收轻质结构。它们的特征来自于在熔融原料的挤出过程中液晶聚合物分子的自组装成高度取向的域。通过用打印路径定向分子结构域，我们能够根据预期的机械应力增强聚合物结构，从而使刚度、强度和韧性超过最先进的3D打印聚合物一个数量级，并与最高性能的轻质复合材料相当（1，12）。联合收割机将3D打印的自上而下的成形自由度与对聚合物取向的自下而上的分子控制相结合的能力开辟了自由设计和实现结构的可能性，而没有当前制造工艺的典型限制。
Fibre-reinforced polymer structures are often used when stiff lightweight materials are required, such as in aircraft, vehicles and biomedical implants. Despite their very high stiffness and strength(1), such lightweight materials require energy- and labour-intensive fabrication processes(2), exhibit typically brittle fracture and are difficult to shape and recycle(3,4). This is in stark contrast to lightweight biological materials such as bone, silk and wood, which form by directed self-assembly into complex, hierarchically structured shapes with outstanding mechanical properties(5-11), and are circularly integrated into the environment. Here we demonstrate a three-dimensional (3D) printing approach to generate recyclable lightweight structures with hierarchical architectures, complex geometries and unprecedented stiffness and toughness. Their features arise from the self-assembly of liquid-crystal polymer molecules into highly oriented domains during extrusion of the molten feedstock material. By orienting the molecular domains with the print path, we are able to reinforce the polymer structure according to the expected mechanical stresses, leading to stiffness, strength and toughness that outperform state-of-the-art 3D-printed polymers by an order of magnitude and are comparable with the highest-performance lightweight composites(1,12). The ability to combine the top-down shaping freedom of 3D printing with bottom-up molecular control over polymer orientation opens up the possibility to freely design and realize structures without the typical restrictions of current manufacturing processes.