Air Force Research Laboratory, Materials and Manufacturing Directorate , 3005 Hobson Way, Wright-Patterson AFB, Ohio 45433-7750, United States.
Azimuth Corporation , 4027 Colonel Glenn Highway, Beavercreek, Ohio 45431, United States.
ACS Appl Mater Interfaces. 2018 Jan 10;10(1):1187-1194. doi: 10.1021/acsami.7b13814. Epub 2017 Dec 26.
Liquid crystal elastomers (LCEs) exhibit anisotropic mechanical, thermal, and optical properties. The director orientation within an LCE can be spatially localized into voxels [three-dimensional (3-D) volume elements] via photoalignment surfaces. Here, we prepare nanocomposites in which both the orientation of the LCE and single-walled carbon nanotube (SWNT) are locally and arbitrarily oriented in discrete voxels. The addition of SWNTs increases the stiffness of the LCE in the orientation direction, yielding a material with a 5:1 directional modulus contrast. The inclusion of SWNT modifies the thermomechanical response and, most notably, is shown to enable distinctive electromechanical deformation of the nanocomposite. Specifically, the incorporation of SWNTs sensitizes the LCE to a dc field, enabling uniaxial electrostriction along the orientation direction. We demonstrate that localized orientation of the LCE and SWNT allows complex 3-D shape transformations to be electrically triggered. Initial experiments indicate that the SWNT-polymer interfaces play a crucial role in enabling the electrostriction reported herein.
液晶弹性体（LCE）表现出各向异性的机械、热和光学性能。通过光取向表面，可以将 LCE 中的指向矢方向在空间上局部定位到体素[三维（3-D）体积元]中。在这里，我们制备了纳米复合材料，其中 LCE 和单壁碳纳米管（SWNT）的取向都在离散的体素中局部和任意取向。SWNT 的添加增加了 LCE 在取向方向上的刚度，得到了一种具有 5:1 定向模量对比度的材料。SWNT 的包含改变了热机械响应，最显著的是，显示出能够使纳米复合材料产生独特的机电变形。具体而言，SWNT 的掺入使 LCE 对直流场敏感，从而能够沿取向方向进行单轴电致伸缩。我们证明了 LCE 和 SWNT 的局部取向允许复杂的 3-D 形状转换被电触发。初步实验表明，SWNT-聚合物界面在实现本文报道的电致伸缩中起着至关重要的作用。
