Self-Folding Liquid Crystal Network Filaments Patterned with Vertically Aligned Mesogens
Self-Folding Liquid Crystal Network Filaments Patterned with Vertically Aligned Mesogens
复制标题
DOI：
10.1021/acsami.2c14947
复制
发表时间：
2022-10-25
影响因子：
9.5
通讯作者：
Yang, Shu
中科院分区：
文献类型：
--
作者：
Kim, Dae Seok;Lee, Young-Joo;Yang, Shu
具有高分子各向异性的纤维软致动器对于响应于外部刺激而具有高致动效率的从1D到2D和3D的形状变形是感兴趣的。然而，很少有制造纤维致动器与控制分子取向和刚度。在这里，我们制造长丝从液晶网络（LCN）与链段交联密度和梯度孔隙率从二丙烯酸酯介晶单体和小分子的液晶或近晶液晶（LC）填充在毛细管的混合物。在光聚合过程中，小分子LC和LCN之间发生相分离，使长丝的一侧比另一侧密度大得多。为了指导其折叠模式（弯曲或扭曲），我们控制毛细管内LC分子的排列，无论是沿着还是垂直于细丝长轴。我们发现，紫外光照射的方向可以决定相分离的方向，这反过来又指导了长丝的变形后，去除小分子液晶。我们发现，在灯丝的LC的垂直对齐是必不可少的，有效地直接弯曲变形。通过对具有链段交联密度的长丝进行图案化，我们可以诱导由在有机溶剂中的去溶胀/溶胀触发的可逆折叠/解折叠成2D和3D几何形状。此外，通过利用LCN的大弹性模量和溶胀前后模量的大对比度，我们表明自折叠的LCP细丝可以充当强有力的夹持器。
Fibrous soft actuators with high molecular anisotropy are of interest for shape morphing from 1D to 2D and 3D in response to external stimuli with high actuation efficiency. Nevertheless, few have fabricated fibrous actuators with controlled molecular orientations and stiffness. Here, we fabricate filaments from liquid crystal networks (LCNs) with segmental crosslinking density and gradient porosity from a mixture of di-acrylate mesogenic monomers and small-molecule nematic or smectic liquid crystals (LCs) filled in a capillary. During photopolymerization, phase separation between the small-molecule LCs and LCN occurs, making one side of the filament considerably denser than the other side. To direct its folding mode (bending or twisting), we control the alignment of LC molecules within the capillary, either along or perpendicular to the filament long axis. We show that the direction of UV exposure can determine the direction of phase separation, which in turn direct the deformation of the filament after removal of the small-molecule LCs. We find that the vertical alignment of LCs within the filament is essential to efficiently direct bending deformation. By photopatterning the filament with segmental crosslinking density, we can induce a reversible folding/unfolding into 2D and 3D geometries triggered by deswelling/swelling in an organic solvent. Moreover, by taking advantage of the large elastic modulus of LCNs and large contrast of the modulus before and after swelling, we show that the self-folded LCP filament could act as a strong gripper.