Nishiguchi Akihiro, Zhang Hang, Schweizerhof Sjören, Schulte Marie Friederike, Mourran Ahmed, Möller Martin
DWI-Leibniz-Institute for Interactive Materials, Forckenbeckstrasse 50, D-52056 Aachen, Germany.
ACS Appl Mater Interfaces. 2020 Mar 11;12(10):12176-12185. doi: 10.1021/acsami.0c02781. Epub 2020 Feb 28.
There is a growing interest in the concept of four-dimensional (4D) printing that combines a three-dimensional (3D) manufacturing process with dynamic modulation for bioinspired soft materials exhibiting more complex functionality. However, conventional approaches have drawbacks of low resolution, control of internal micro/nanostructure, and creation of fast, complex actuation due to a lack of high-resolution fabrication technology and suitable photoresist for soft materials. Here, we report an approach of 4D printing that develops a bioinspired soft actuator with a defined 3D geometry and programmed printing density. Multiphoton lithography (MPL) allows for controlling printing density in gels at pixel-by-pixel with a resolution of a few hundreds of nanometers, which tune swelling behaviors of gels in response to external stimuli. We printed a 3D soft actuator composed of thermoresponsive poly(-isopropylacrylamide) (PNIPAm) and gold nanorods (AuNRs). To improve the resolution of printing, we synthesized a functional, thermoresponsive macrocrosslinker. Through plasmonic heating by AuNRs, nanocomposite-based soft actuators undergo nonequilibrium, programmed, and fast actuation. Light-mediated manufacture and manipulation (MPL and photothermal effect) offer the feasibility of 4D printing toward adaptive bioinspired soft materials.
将三维（3D）制造工艺与动态调制相结合的四维（4D）打印概念，正引发越来越多的关注，该技术可用于制造具有更复杂功能的仿生软材料。然而，由于缺乏高分辨率制造技术和适用于软材料的光刻胶，传统方法存在分辨率低、难以控制内部微/纳米结构以及无法实现快速、复杂驱动等缺点。在此，我们报道了一种4D打印方法，该方法可制造具有特定3D几何形状和编程打印密度的仿生软驱动器。多光子光刻（MPL）能够以数百纳米的分辨率逐像素控制凝胶中的打印密度，进而调节凝胶在外部刺激下的溶胀行为。我们打印了一种由热响应性聚（N-异丙基丙烯酰胺）（PNIPAm）和金纳米棒（AuNRs）组成的3D软驱动器。为提高打印分辨率，我们合成了一种功能性热响应性大分子交联剂。通过AuNRs的等离子体加热，基于纳米复合材料的软驱动器能够实现非平衡、程序化和快速驱动。光介导的制造与操控（MPL和光热效应）为4D打印制备自适应仿生软材料提供了可行性。
