Title: Multiple Shape Manipulation of Liquid Crystal Polymers Containing Diels-Alder Network

Author: Xin Huang, Lang Qin, Jinlei Wang, Xiao Zhang, Bo Peng, Yanlei Yu*

Journal: Adv. Funct. Mater., 2022, 32(51), 2208312

Abstract:

Multiple shape manipulation of soft materials, including reversible deformation, shape memory effect, and shape remolding, are highly desirable in morphing structures and soft actuators. Although liquid crystal network (LCN) is a promising candidate for realizing anisotropic reversible deformation, developing LCN with multiple shape manipulation remains a multitude of challenges, which is limited to the regulation of mesogens alignment and network topological rearrangement. Here, multiple shape manipulation is demonstrated by a newly designed LCN containing azobenzene moieties and a dynamic Diels-Alder (DA) network. Photodeformation of the LCN is attributed to the ordered lamellar structure of mesogens formed by annealing-induced self-assembly. Light-induced shape memory effect leads to reprogrammable shape changes due to the light-switchable glass transition temperature of the azobenzene-containing LCN. Moreover, the dynamic equilibrium of the DA network endows the LCN with liquid state remoldability and solid state plasticity, which further contributes to diverse 3D geometric shapes in shape remolding. Such LCN exhibiting flexible deformation and remolding properties provides a new photoresponsive block for the fabrication of soft actuators.

Fulltext Link: https://onlinelibrary.wiley.com/doi/10.1002/adfm.202208312

In this work, we have prepared a new azobenzene liquid crystal polymer (AZO-DAN) containing dynamic Diels Alder (D-A) cross-linking network. Azobenzene groups as optical switches can not only control the change of liquid crystal alignment, but also reversibly control the glass transition temperature of the polymer to change at room temperature, so that liquid crystal molecules have both the ability of photodeformation and light-induced shape memory effect; In addition, D-A dynamic network endows the material with the ability of liquid state remoldability and solid state plasticity. This azobenzene liquid crystal polymer is expected to prepare all optical actuators with complex shapes, expanding the deformation mode of liquid crystal polymer and its application in soft robots and other fields.