PIEZOELECTRIC EFFECT OF PUE FILMS CONTROLLED BY CARBON NANOTUBES (CNTs) AND ITS ACTUATION MECHANISM

本文的研究结果总结如下：1。我们提出利用聚氨酯弹性体（PUE）薄膜的电致伸缩效应，将其应用于无离子溶剂的致动器等移动装置中。该驱动器为单晶型，由PUE薄膜和在两个薄膜表面蒸发相同厚度（200nm）的金属电极制成。由于这些致动器工作在超过1kv的高压下，我们通过在PUE中掺杂碳纳米管（CNTs）衍生物来控制薄膜的分子结构，从而使致动器可以在较低的电压下工作。掺杂碳纳米管的PUE致动器的弯曲位移随电场的平方而变化。所有PUE致动器的样品都在与金属材料无关的阴极电极方向弯曲。他们表现出一种极性效应。掺杂碳纳米管后的致动器弯曲度比普通致动器大，工作电压为300 V。此外，弯曲位移强烈依赖于CNTs.6中羟基的数量。掺杂碳纳米管致动器的感应力与施加电压成正比，并显著依赖于薄膜厚度。薄膜厚度为200 μm的作动器力最强，可提升700 mg的载荷7。为了明确致动器的弯曲机制，我们使用脉冲电声方法测量了不同类型PUE薄膜（正常、富勒烯醇和掺杂碳纳米管薄膜）的空间电荷。通过对分子链极性基空间电荷的测量，发现分子链由于阴极上的正负电荷而受到电磁力的吸引。结果表明，所有PUE薄膜驱动器均沿阴极电极方向弯曲。这些PUE薄膜也出现了压电效应。

The results of this research are summarized as follows.1.We proposed their application to moving devices such as an actuator without ionic solvents using the electrostriction effect of polyurethane elastomer (PUE) films.2.The actuators are of monomorph type fabricated by PUE film and metal electrodes evaporated at same thickness (200nm) on the both film surfaces.3.Since these actuators work at high voltages more than 1 KV, we controlled the molecular structure of the film by doping carbon nanotubes (CNTs) derivative into PUE so that the actuators could operate under a lower voltage.4.The bending displacement of the CNTs-doped PUE actuator varied with the square of the electric field. All samples of PUE actuator bent in the direction of the cathode electrode independent of the metal materials. They exhibited a polarity effect.5.The bends of these actuators were larger than normal actuators by doping CNTs and its operating voltage took place at 300 V. Moreover, the bending displacement strongly depends on the number of hydroxyl groups of CNTs.6.The induced forces of the CNTs-doped actuator increased in proportion to applied voltage, and significantly depended on film thickness. The actuator with a film thickness of 200 μm had the strongest force and could lift up to a load of 700 mg.7.In order to clear the bending mechanism of actuators, we measured the space charges of the various kinds of PUE films (normal, fullerenol and CNTs-doped films) by using the pulsed electro-acoustic method.8.We have found that molecule chains are attracted each other by electric force due to the positive and negative charges at cathode electrode from measurement of space charge based on the polar groups of molecular chain. As a result, it was concluded that the all PUE film actuators always bend in the direction of cathode electrode.9.These PUE films also appeared the piezoelectric effect.