Title: Photodeformable Main-chain Crosslinked Liquid Crystal Polymer Fiber Actuators at Room Temperature

Author: Xin Huang, Xinlei Pang, Lang Qin, Yanlei Yu*

Journal: Acta Polymerica Sinica, 2022, 53(11), 1324-1331


Photodeformable crosslinked liquid crystal polymer fiber actuators have potential applications in soft robots and other fields. However, due to the limitations of processing methods, it is still a great challenge to fabricate fiber actuators that can undergo large and direction-controllable light-induced bending at room temperature. Here, the main-chain liquid crystal oligomer with controllable molecular weight is synthesized by the Michael addition reaction between primary amines and liquid crystal monomers containing azobenzene or phenyl benzoate mesogens respectively. On the basis, the cross-linked liquid crystal polymer fiber is obtained through dip-drawing the melt oligomer followed by the radical polymerization. The chain extension reaction between the primary amine and liquid crystal monomers effectively decreases the crosslinking density of the polymer network, thus lowering the glass transition temperature. Meanwhile, the alignment and crosslinking processes are decoupled by the strategy that the oligomer is stretched first and then the polymerization is implemented, which ensures that mesogens in the fiber are aligned along the stretching direction. Accordingly, the aligned fiber exhibits reversible light-induced bending at room temperature, whose maximum bending angle is close to 60°, and furthermore the bending direction can be adjusted by the light irradiation direction. The main-chain crosslinked liquid crystal polymer fiber with large and direction-controllable deformation has great potential in the field of soft robots. In addition, the method of processing oligomers and then polymerizing actuators is expected to be combined with the template method and 3D printing to fabricate actuators with complex shapes, promoting the development of photoresponsive flexible actuators and other fields.

Fulltext Link: http://www.gfzxb.org/thesisDetails#10.11777/j.issn1000-3304.2022.22103&lang=zh