Voxelated Molecular Patterning in Three-Dimensional Freeforms
Voxelated Molecular Patterning in Three-Dimensional Freeforms
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DOI：
10.1021/acsami.9b04480
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发表时间：
2019-08-07
影响因子：
9.5
通讯作者：
Shankar, M. Ravi
中科院分区：
文献类型：
--
作者：
Tabrizi, Mohsen;Ware, Taylor H.;Shankar, M. Ravi
逐体素地图案化材料响应以在宏观结构中引导致动和操纵的能力可以使得利用环境刺激的设备能够在从微观到宏观的范围内的长度尺度上产生功能响应。制造液晶聚合物（LCP），其中分子指向矢以三维（3D）自由形式可索引地定义，可以是一个关键的推动者。在这里，利用了在可重定向磁场中液晶单体的各向异性磁化率和空间选择性光聚合的组合，所述空间选择性光聚合使用数字微控制器装置来独立地限定光和/或热响应性多材料元件中的分子取向，所述光和/或热响应性多材料元件被添加地并入到3D自由形式中。这表明，使结构的复杂性跨越长度尺度在非平凡的几何形状，包括再入形状，这是响应于热或光。优化一系列单体组合物以包括光引发剂、光吸收剂和聚合抑制剂，以调节聚合特性，同时保持聚合物取向的可定制性。该框架的多功能性在一系列示例中示出，包括（i）从平坦几何形状热机械生成高斯弯曲结构，（ii）光响应自由形态形貌，以及（iii）多响应操纵器，其可以使用热和/或光沿着独立轴供电。集成对多个刺激的响应的能力，其中机械输出的主要方向在3D自由形式中任意定制，使软机器人，微机械/流体系统和光学机械系统中的新设计空间成为可能。
The ability to pattern material response, voxel by voxel, to direct actuation and manipulation in macroscopic structures can enable devices that utilize ambient stimuli to produce functional responses at length scales ranging from the micro- to the macroscopic. Fabricating liquid crystalline polymers (LCPs), where the molecular director is indexably defined in three-dimensional (3D) freeforms, can be a key enabler. Here, the combination of anisotropic magnetic susceptibility of the liquid crystalline monomers in a reorientable magnetic field and spatially selective photopolymerization using a digital micromirror device to independently define molecular orientation in light and/or heat-responsive multimaterial elements, which are additively incorporated into 3D freeforms, is exploited. This is shown to enable structural complexity across length scales in nontrivial geometries, including re-entrant shapes, which are responsive to either heat or light. A range of monomer compositions are optimized to include photoinitiators, light absorbers, and polymerization inhibitors to modulate the polymerization characteristics while simultaneously retaining the tailorability of the nematic alignment. The versatility of this framework is illustrated in an array of examples, including (i) thermomechanical generation of Gaussian-curved structures from flat geometries, (ii) light-responsive freeform topographies, and (iii) multiresponsive manipulators, which can be powered along independent axes using heat and/or light. The ability to integrate responses to multiple stimuli, where the principal directions of the mechanical output are arbitrarily tailored in a 3D freeform, enables new design spaces in soft robotics, micromechanical/fluidic systems, and optomechanical systems.