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_NI). 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.

中文翻译：

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能够切换形状的液晶弹性体微粒中的永久性和可逆编程形状

通过硫醇-迈克尔分散聚合合成了可逆可编程液晶弹性体微粒（LCEMP），形成为共价自适应网络（CAN），平均直径为7μm±2μm 。通过在受压后激活AFT，通过光引发的加成-断裂链转移（AFT）交换反应将颗粒编程为长条形。由于AFT-LCEMP具有热致性，通过将粒子加热至其向列-各向同性相变温度（T _NI）。当在低温或高温下时，被编程的粒子随后分别显示出从长圆形到球形的可循环的双向形状转换。此外，形状编程是可逆的，并且执行第二编程步骤以通过在颗粒为球形时在高温下启动AFT来擦除长条形。冷却后，颗粒保持球形，直到采取其他编程步骤为止。还对粒子进行编程以保持永久的扁圆形。此外，用衍射光栅对粒子表面进行编程，以显示通过AFT激活实现的可编程复杂表面形貌。