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Abstract：
Human muscles can grow and change their length with body development; therefore, artificial muscles that modulate their morphology according to changing needs are needed. In this paper, we report a strategy to transform an artificial muscle into a new muscle with a different morphology by thermodynamic-twist coupling, and illustrate its structural evolution during actuation. The muscle length can be continuously modulated over a large temperature range, and actuation occurs by continuously changing the temperature. This strategy is applicable to different actuation modes, including tensile elongation, tensile contraction and torsional rotation. This is realized by twist insertion into a fibre to produce torsional stress. Fibre annealing causes partial thermodynamic relaxation of the spiral molecular chains, which serves as internal tethering and inhibits fibre twist release, thus producing a self-supporting artificial muscle that actuates under heating. At a sufficiently high temperature, further relaxation of the spiral molecular chains occurs, resulting in a new muscle with a different length. A structural study provides an understanding of the thermodynamic-twist coupling. This work provides a new design strategy for intelligent materials.
摘要：
人体肌肉可以随着身体的发育而生长和改变其长度；因此，需要根据不断变化的需求调节其形态的人造肌肉。在本文中,我们报告了一种策略，通过热力学扭曲耦合将人造肌肉转变为具有不同形态的新肌肉，并说明其在驱动过程中的结构演变。肌肉长度可以在很大的温度范围内连续调节，和致动通过连续改变温度而发生。该策略适用于不同的驱动模式，包括拉伸伸长率，拉伸收缩和扭转旋转。这是通过扭曲插入纤维中以产生扭转应力来实现的。纤维退火导致螺旋分子链的部分热力学弛豫，用作内部束缚并抑制纤维扭曲释放，从而产生在加热下启动的自支撑人造肌肉。在足够高的温度下，螺旋分子链进一步松弛，产生不同长度的新肌肉。结构研究提供了对热力学-扭曲耦合的理解。这项工作为智能材料提供了一种新的设计策略。
