Martinez Alina M, Cox Lewis M, Killgore Jason P, Bongiardina Nicholas J, Riley Russell D, Bowman Christopher N
Department of Materials Science and Engineering, University of Colorado Boulder, 596 UCB, Boulder, CO 80309, USA.
Department of Mechanical Engineering, Montana State University, Culbertson Hall, 100, Bozeman, MT 59717, USA.
Soft Matter. 2021 Jan 21;17(3):467-474. doi: 10.1039/d0sm01836h. Epub 2020 Dec 21.
Reversibly programmable liquid crystal elastomer microparticles (LCEMPs), formed as a covalent adaptable network (CAN), with an average diameter of 7 μm ± 2 μm, were synthesized via a thiol-Michael dispersion polymerization. The particles were programmed to a prolate shape via a photoinitiated addition-fragmentation chain-transfer (AFT) exchange reaction by activating the AFT after undergoing compression. Due to the thermotropic nature of the AFT-LCEMPs, shape switching was driven by heating the particles above their nematic-isotropic phase transition temperature (T). The programmed particles subsequently displayed cyclable two-way shape switching from prolate to spherical when at low or high temperatures, respectively. Furthermore, the shape programming is reversible, and a second programming step was done to erase the prolate shape by initiating AFT at high temperature while the particles were in their spherical shape. Upon cooling, the particles remained spherical until additional programming steps were taken. Particles were also programmed to maintain a permanent oblate shape. Additionally, the particle surface was programmed with a diffraction grating, demonstrating programmable complex surface topography via AFT activation.
通过硫醇-迈克尔分散聚合反应合成了平均直径为7μm±2μm、呈共价适应性网络（CAN）形式的可逆可编程液晶弹性体微粒（LCEMPs）。通过在压缩后激活光引发的加成-断裂链转移（AFT）交换反应，将这些微粒编程为长椭球形。由于AFT-LCEMPs的热致性，通过将微粒加热到其向列相-各向同性相转变温度（T）以上来驱动形状切换。随后，编程后的微粒在低温或高温时分别显示出从长椭球形到球形的可循环双向形状切换。此外，形状编程是可逆的，在微粒呈球形时通过在高温下引发AFT进行第二步编程以消除长椭球形。冷却后，微粒保持球形，直到采取额外的编程步骤。微粒还被编程以保持永久的扁球形。此外，微粒表面通过衍射光栅进行编程，展示了通过AFT激活实现可编程的复杂表面形貌。
