Photopatterning Crystal Orientation in Shape-Morphing Polymers
Photopatterning Crystal Orientation in Shape-Morphing Polymers
复制标题
形状变形聚合物中的光致结晶取向
DOI：
10.1021/acsami.1c15630
复制
发表时间：
2022-05-25
影响因子：
9.5
通讯作者：
Ware, Taylor H.
中科院分区：
文献类型：
--
作者：
Jang, Lindy K.;Abdelrahman, Mustafa K.;Ware, Taylor H.
变形聚合物因其在光、pH 和温度等多种外部刺激下具有独特的形状转变能力而受到特别关注。它们的形状变形特性可用于各种应用，例如机器人、人造肌肉和生物医学设备。为了在此类应用中利用智能聚合物的刺激响应特性，通过简单的合成程序精确编程形状变化至关重要。在水凝胶和液晶聚合物网络中很容易实现可编程形状变形，但半结晶聚合物的形状编程通常依赖于低分辨率机械变形。在本文中，使用空间控制光聚合技术通过光图案化晶体取向开发了一种具有受控形状可编程性的半结晶形状变形聚合物。在使用投影仪进行光聚合过程中，半结晶聚合物网络在暗区和亮区之间的边界处形成排列的微晶，这在薄膜中引入了各向异性刺激响应。当加热到熔化温度以上时，具有光取向微晶的半结晶聚合物薄膜在垂直于图案线的方向上膨胀9-15%。此外，通过对晶体取向进行空间图案化，可以形成各种复杂的 3D 结构，包括螺旋线圈、旋向反转线圈、锥体、鞍形和扭转花形。最后，通过改变聚合温度来控制形状转变的幅度，并通过改变聚合物薄膜中的结晶度来调节驱动温度。我们从 2D 半结晶聚合物薄膜编程复杂 3D 结构的方法简单且易于控制，使其成为上述应用的有前途的系统。
Shape-morphing polymers have gained particular attention due to their unique capability of shape transformation under numerous external stimuli such as light, pH, and temperature. Their shape-morphing properties can be used in various applications such as robotics, artificial muscles, and biomedical devices. To take advantage of the stimuli-responsive properties of the smart polymers in such applications, programming shape change precisely through a facile synthetic procedure is essential. Programmable shape-morphing is readily obtained in hydrogels and liquid crystal polymer networks, but shape programming of semicrystalline polymers usually relies on low-resolution mechanical deformation. In this paper, a semicrystalline shape-morphing polymer with a controlled shape programmability was developed via photopatterning crystal orientation using a spatially controlled photopolymerization technique. The semicrystalline polymer network forms aligned crystallites at the boundaries between dark and bright regions during photopolymerization using a projector, which introduces an anisotropic stimulus response in the films. The semicrystalline polymer films with photoaligned crystallites expand 9-15% in the direction perpendicular to the patterned lines when heated above the melting temperature. Furthermore, spatially patterning the crystal orientation enables the formation of various complex 3D structures including a helical coil, a coil with a handedness inversion, a cone, a saddle, and a twisting flower. Finally, the magnitude of the shape transformation was controlled by varying the polymerization temperatures, and the actuation temperature was tuned by changing the amount of crystallinity in the polymer films. The simplicity and ease of control of our approach to program complex 3D structures from 2D semicrystalline polymer films make it a promising system for the aforementioned applications.