Bauman Grant E, Koch Jeremy A, White Timothy J
Department of Chemical and Biological Engineering, University of Colorado, Boulder, Colorado, 80309, USA.
Soft Matter. 2022 Apr 20;18(16):3168-3176. doi: 10.1039/d2sm00166g.
Liquid crystalline monomers can be oligomerized and subsequently 3-D printed to prepare liquid crystalline elastomers (LCEs) with spatial variation of the nematic director to create soft materials that undergo complex shape change when subject to stimulus. Here, we detail the correlation of alignment in 3-D printed LCE on the shear history of the oligomeric ink. This coupling is evident both in the polymerization of sheared LCE samples as well as steady-state rheological experiments that quantify the time-dependent flow behaviors of these complex fluids. Under a steady shear flow, oligomeric LC inks transition from a nematic state with unaligned (polydomain) orientation to a uniaxially aligned (monodomain) nematic phase over a large range of applied strain. After cessation of shear flow, the oligomeric LC inks return the polydomain orientation over approximately 30 minutes. The alignment of liquid crystalline segments in the LCE (and the associated stimuli-response of the materials) is ultimately correlated to the degree of strain applied to the ink.
液晶单体可以进行低聚反应，随后通过3D打印来制备具有向列型指向矢空间变化的液晶弹性体（LCE），从而制造出在受到刺激时会发生复杂形状变化的软材料。在此，我们详细阐述了3D打印的LCE中的取向与低聚物油墨剪切历史之间的相关性。这种耦合在剪切后的LCE样品的聚合过程以及量化这些复杂流体随时间变化的流动行为的稳态流变实验中都很明显。在稳定剪切流作用下，低聚物液晶油墨在大范围的外加应变下，从具有未取向（多畴）取向的向列态转变为单轴取向（单畴）的向列相。停止剪切流后，低聚物液晶油墨在大约30分钟内恢复到多畴取向。LCE中液晶链段的取向（以及材料相关的刺激响应）最终与施加到油墨上的应变程度相关。
