响应性软材料能够在外部刺激下进行复杂、可逆且快速的几何变形，在微创医学、可穿戴设备和软体机器人等领域具有巨大应用潜力。
近日，中国科学技术大学徐航勋教授等人在Science China Materials发表研究论文，提出了一种通过光热编程设计可重构三维变形磁性软材料的新方法。
本文要点
1) 通过将硬磁性颗粒嵌入由纤维状聚吡咯（PPy）和半结晶聚合物组成的聚合物材料中，开发出了一种磁性复合材料，该材料可以在外部磁场下进行远程控制，实现精确的可编程变形。2) 该方法重要的创新点在于，利用PPy的光热效应，当材料受到红外光辐照时，复合材料的黏度发生暂时改变，从而允许磁性颗粒进行动态可控定向运动；冷却后，磁性各向异性固化，材料能够快速且可逆地进行几何变形。3) 该方法能够对磁化分布进行精细控制，从而开发出多功能设备，具有诸如软体机器人复杂三维变形、多模态电气开关、可重写的快速响应码以及可变形夹具等多种潜在应用。本研究不仅加深了对软材料中磁矩编程的理解，也为自适应和响应性材料的设计开辟了新的途径，推动了先进技术应用的发展。Figure 1. (a) Schematically illustrating the concept of manipulating magnetic anisotropy in the rationally designed magnetic composite via photothermal programming. (b) Differential scanning calotimetry curves of the semi-crystalline polymer and magnetic composite. (c) Rheological properties of the magnetic composite. (d) Variations of magnetic flux densities of the magnetic composite with different contents of NdFeB particles before and after photothermal programming.![]()
Figure 2. (a) Hysteresis loops of magnetic thermoplastics at different temperatures. (b) Schematic of three different magnetization patterns in the same material film, and their corresponding magnetic flux density distributions. (c) Optical images showing the reorientation of NdFeB particles in material film after reprogramming, and the corresponding magnetization patterns. Scale bars: 10 μm. (d) Optical images showing the arrangement of NdFeB particles in the film after reprogramming, along with the corresponding magnetization patterns. The yellow arrow indicates the direction of the magnetic moment. Scale bars: 200 μm.Figure 3. (a) Schematic illustration of an electrical circuit using a programmable magnetic thin film as the switch to control the function of LEDs. (b) Photograph of the device (front view). (c) Experimental results showing the magnetically controlled operation of the switch. The magnetic thin films are activated under a magnetic field of 20 mT. Scale bars: 5 mm.Figure 4. (a–c) Schematically showing three different magnetization distributions in a magnetic thin film and their corresponding motion modes under a dynamic magnetic field. (d) Photographs showing the movements of the magnetic thin film: discontinuously crawling through the spinous plate, passing through the slit, and jumping over the cube. The strength of the applied magnetic field is 150 mT. Scale bars: 5 mm.Yiwen Bao, Jiyu Li, Tao Wang, Liu Wang, Hangxun Xu. Yiwen Bao, Jiyu Li, Tao Wang, Liu Wang, Hangxun Xu. Photothermalprogramming of magnetic soft materials for complex and reconfigurable 3D deformations. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3107-8
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