响应性交联液晶高分子仿生致动器的研究进展

交联液晶高分子兼具液晶取向有序性和交联聚合物熵弹性等特点,能够以动态可调节和可逆的方式来模仿生物体的行为,在仿生器件、柔性机器人、智能表面、生物医药等领域具有良好的应用前景.本综述总结了近几年智能响应性交联液晶高分子在仿生致动器方面的研究进展,从响应性交联液晶高分子的结构和驱动机理出发,讨论了响应性交联液晶高分子的合成工艺、制备技术和成型方法,以及响应性交联液晶高分子对光、热、磁、湿度的响应.此外,介绍了响应性交联液晶高分子致动器在柔性机器人、人工肌肉、微流体运输等领域的应用.最后,对响应性交联液晶高分子的发展前景进行了展望.这项工作主要讨论了响应性交联液晶高分子,旨在为具有新颖功能和更有挑战性的智能微型致动器提供新的设计思路.

Research Progress in Biomimetic Actuators of Responsive Cross-linked Liquid Crystal Polymer

Cross-linked liquid crystal polymer(CLCP),as a combination of the order of liquid crystal orientation and the entropy elasticity of the polymer network,has exhibited unique properties such as actuation,soft elasticity,and birefringence.CLCP can mimic the behavior of organisms in a dynamically adjustable and reversible way to achieve actuation.When subjected to a specific external stimulus(such as light,heat,magnetism,or humidity),CLCP responds to the stimuli by presenting changes in LC arrangement at the micro level and reversible shape or size changes at the macro level.Because of the initial arrangement of the mesogen memorized through the network,the macroscopic deformation of CLCP is reversible.Materials with photothermal conversion effect,such as graphene,carbon nanotubes,and gold nanorods,can be combined with polymers to convert the absorbed light energy into heat energy so as to realize photothermal actuation.In addition,when photo-response moieties like azobenzene are appropriately added to CLCP,the reversible trans-cis isomerization of azobenzene under specific wavelengths of light will cause the change of LC director,thus bringing out its photodeformation performance.Moreover,there is also magnetic stimulation driven by magnetic fields and humidity stimulation based on CLCP reversible anisotropic contraction or expansion.In this review,the synthesis methods of CLCP(one-step crosslinking,two-step cross-linking,post-crosslinking,and dynamic covalent bond cross-linking)and molding technology(inkjet printing,microfluidic transportation,soft lithography,direct laser writing,and 4D printing)are described.Through reasonable structure and material design,CLCP can be fabricated into a variety of flexible actuators.Herein,this review mainly summarizes the recent research progress in the applications of intelligently responsive cross-linked liquid crystal polymer in the field of the biomimetic actuators,such as artificial muscles,and microfluidic transportation.The future development and challenges of intelligently responsive cross-linked liquid crystal polymer in actuator field are also discussed.