Zhou Lin, Wang Yujie, Li Kai
School of Mechanical and Electrical Engineering, Anhui Jianzhu University, Hefei 230601, China.
Department of Civil Engineering, Anhui Jianzhu University, Hefei 230601, China.
Polymers (Basel). 2022 Mar 20;14(6):1249. doi: 10.3390/polym14061249.
Nematic elastomer balloons with inflation-induced axial contraction and shear/torsion effect can be used as actuators for soft robots, artificial muscles, and biomedical instruments. The nematic elastomer can also generate drastic shape changes under illumination, and thus light can be utilized to activate the deformation of nematic elastomer balloons with huge advantages of being accurate, fast, untethered, and environmentally sustainable without chemical byproducts. To explore light-activated deformation behaviors of the balloon, a phenomenological relationship between light intensity and material parameters describing polymer backbone anisotropy is proposed from experiments, and a theoretical model of an optically-responsive nematic elastomer balloon is established based on the nematic elastomer theory. Various light-activated elongation/shortening and twisting behaviors in the cases of free-standing and axial-loading are presented and their mechanisms are elucidated. The light intensity and initial mesogen angle have great influences on the light-activated deformations including the radius, length, shearing angle and mesogen angle. Light can be easily controlled to trigger rich deformation processes, including elongation/shortening and torsion. The results of this paper are expected to promote the understanding of the light-activated deformation behaviors of the nematic elastomer balloon, and the applications in light-activated actuators and machines.
具有充气诱导轴向收缩以及剪切/扭转效应的向列型弹性体气球可作为软机器人、人造肌肉和生物医学仪器的致动器。向列型弹性体在光照下也能产生剧烈的形状变化，因此光可用于激活向列型弹性体气球的变形，具有精确、快速、无需系绳且环境可持续且无化学副产物等巨大优势。为了探究气球的光激活变形行为，通过实验提出了光强与描述聚合物主链各向异性的材料参数之间的唯象关系，并基于向列型弹性体理论建立了光响应向列型弹性体气球的理论模型。给出了自由站立和轴向加载情况下各种光激活伸长/缩短和扭转行为，并阐明了其机理。光强和初始液晶元角度对包括半径、长度、剪切角和液晶元角度在内的光激活变形有很大影响。光可以很容易地被控制以引发丰富的变形过程，包括伸长/缩短和扭转。本文的结果有望促进对向列型弹性体气球光激活变形行为的理解，以及在光激活致动器和机器中的应用。
