Soft actuators based on liquid-crystalline elastomers.
Soft actuators based on liquid-crystalline elastomers.
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DOI：
10.1002/anie.200601760
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发表时间：
2006-08
影响因子：
--
通讯作者：
Yanlei Yu;T. Ikeda
中科院分区：
文献类型：
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作者：
Yanlei Yu;T. Ikeda
人们对人工肌肉类致动器的发展越来越感兴趣，这是实现仿生运动的理想选择，因为当施加电势时，它们会改变形状和尺寸。聚合物致动器在这一领域发挥着主导作用，因为它们提供了灵活性，重量轻，成本低，安静的操作合规性等优点。[1]目前在这一领域正在研究各种材料，例如聚合物凝胶，[1]共轭聚合物，[2]碳纳米管，[3]和介电弹性体，[4]以及各种化学和物理刺激已被应用于诱导这些材料的响应，包括pH值，溶剂组成，温度，电场，磁场和光。在这些聚合物软驱动材料中，凝胶和导电聚合物在仿生驱动领域的应用最有前途。然而，凝胶的低弹性模量和低屈服强度为致动器性能提供了重要的限制，而对于电池状导电聚合物，涉及固态掺杂剂扩散和结构变化的法拉第过程限制了速率、循环寿命和能量转换效率。基于液晶弹性体（LCE）的软致动材料的研究越来越受到人们的关注这是由于它们独特地结合了液晶（LC）相的各向异性特征和聚合物网络的橡胶弹性。1997年，deGennes埃塔尔.报告了关于使用LCE作为人造肌肉的可能性的理论研究。[5]他们提出，在各向同性（I）到LC转变的温度的轻微下降能够导致LCE在几乎恒定的体积下由于LC顺序的变化而发生强烈的单轴变形。Finkelmann和Kundler后来报告说，当加热到N-到-I相变温度时，含有聚硅氧烷的NLCE（NLCE）薄膜沿指向矢轴沿着自发收缩（图1）。[6a]通过单官能LC化合物和双官能LC聚醚与聚（甲基氢硅氧烷）的硅氢加成反应合成NLCE膜，获得超过300%的形状变化。[6b这种热机械效应也在侧面NLCE膜和纤维中观察到，
There is a growing interest in the development of artificial muscle-like actuators, which are ideal for the realization of biomimetic movements as they change their shapes and dimensions when a potential is applied. Polymer actuators play a leading role in this field because they provide such advantages as flexibility, light weight, low costs, and quiet operation compliance.[1] Various materials are under current investigation in this field, such as polymer gels,[1] conjugated polymers,[2] carbon nanotubes,[3] and dielectric elastomers,[4] and various chemical and physical stimuli have been applied to induce the responses of these materials, including pH, solvent composition, temperature, electric field, magnetic field, and light. Among these polymer soft actuation materials, gels and conducting polymers are most promising for applications in the field of biomimetic actuation. However, the low elastic modulus and low yield strength of gels provide important limitations for actuator performance, whereas for battery-like conducting polymers faradaic processes involving solid-state dopant diffusion and structural changes limit the rate, cycle life, and energy conversion efficiencies.Recently, there has been a growing focus on the study of soft actuation materials based on liquid-crystalline elastomers (LCEs) as a result of their unique combination of the anisotropic features of liquid crystal (LC) phases and the rubber elasticity of polymer networks. In 1997, deGennes etal. reported theoretical studies on the possibility of using LCEs as artificial muscles.[5] They proposed that a slight drop in the temperature across the isotropic (I)-to-LC transition is able to cause a strong uniaxial deformation of LCEs at nearly constant volume owing to a change in the LC order. Finkelmann and Kundler later reported that nematic LCE (NLCE) films containing polysiloxanes exhibited a spontaneous contraction along the director axis when heated toward the N-to-I phase-transition temperature (Figure 1).[6a] By synthesizing NLCE films through a hydrosilylation reaction of a monofunctional LC compound and a bifunctional LC polyether with poly (methylhydrogensiloxane), a shape change over 300% was obtained.[6b, c] This thermomechanical effect was also observed in side-on NLCE films and fibers that contained poly-