Department of Chemistry, University of Toronto, Toronto, Ontario, MSB M5B.
J Am Chem Soc. 2010 Mar 17;132(10):3236-7. doi: 10.1021/ja9089236.
Cross-linked conductive polymer networks that mediate chemical, electronic, optical, and mechanical signals are enticing materials from which to construct actuators and sensors as well as more complex polymer-fiber-based structures capable of emulating natural cytoskeletal stress fibers such as actin. In this work we have synthesized and characterized a novel class of high molecular weight electroactive polyferrocenylsilane (PFS) that has been functionalized with pendant alkoxysilane groups and which can be conveniently gelled by sulfonic acid catalyzed condensation of the cross-linkable alkoxysilanes. These PFS electroactive gels are capable of converting an electrical signal to mechanical stress and strain as a result of a change in dimension in response to electrochemical oxidation or reduction coupled with transport of charge balancing ions and solvent molecules in PFS. Electrospinning of these polymer solutions is possible using a 5 kV voltage applied between a needle and indium tin oxide (ITO) substrate on to which fibers are collected. ITO substrates with collected fibers thereupon are incorporated into miniature electrochemical cells containing lithium triflate/gamma-butyrolactone electrolyte and examined using optical microscopy. Applying 1.5-2.0 V anodic potential to the ITO results in immediate oxidation of PFS fibers followed by strain induced buckling. This buckling occurs in many cases as regular sinusoid perturbations along the fiber. Application of cathodic 2.0 V potential causes most of the distorted fibers to return to their initial form. Such inherent shape memory is potentially useful in creating microswitches, microactuators, and micromanipulators.
交联导电聚合物网络可以传递化学、电子、光学和机械信号，是一种很有吸引力的材料，可以用来构建执行器和传感器，以及更复杂的基于聚合物纤维的结构，这些结构可以模拟天然细胞骨架中的应力纤维，如肌动蛋白。在这项工作中，我们合成并表征了一类新型的高分子量电活性聚二茂铁硅烷（PFS），它带有悬挂的烷氧基硅烷基团，并且可以通过磺酸催化的可交联烷氧基硅烷的缩合方便地凝胶化。这些 PFS 电活性凝胶能够将电信号转换为机械应力和应变，这是由于尺寸的变化响应电化学氧化或还原，伴随着电荷平衡离子和溶剂分子在 PFS 中的传输。通过在针和铟锡氧化物（ITO）基底之间施加 5 kV 的电压，可以将这些聚合物溶液进行电纺丝，纤维收集在 ITO 基底上。随后，将收集有纤维的 ITO 基底纳入包含三氟甲磺酸锂/γ-丁内酯电解质的微型电化学电池中，并使用光学显微镜进行检查。将 1.5-2.0 V 的阳极电势施加到 ITO 上，会导致 PFS 纤维立即氧化，随后应变诱导的弯曲。在许多情况下，这种弯曲会沿着纤维以规则的正弦波形式出现。施加 2.0 V 的阴极电势会导致大部分变形的纤维恢复到初始形状。这种固有形状记忆在制造微开关、微执行器和微操作器方面具有潜在的用途。
