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

本论文的主要研究成果如下：1.利用聚氨酯弹性体（PUE）薄膜的电致伸缩效应，提出了将其应用于无离子溶剂驱动器等运动器件的设想; 2.利用PUE薄膜和在两个薄膜表面蒸镀相同厚度（200 nm）的金属电极制备了单晶型的驱动器; 3.由于这些驱动器工作在1 KV以上的高压下，通过在PUE中掺杂碳纳米管（CNTs）衍生物来控制PUE薄膜的分子结构，使其能够在较低的电压下工作。4. CNTs掺杂PUE致动器的弯曲位移随电场的平方变化。PUE致动器的所有样品在阴极电极的方向上弯曲，与金属材料无关。结果表明：与普通致动器相比，掺杂CNTs的致动器的弯曲位移较大，其工作电压为300 V，且弯曲位移与CNTs的羟基数目密切相关; 6.掺杂CNTs的致动器的诱导力与外加电压成正比增加，并与薄膜厚度有显著的依赖关系。膜厚为200 μm的致动器的力最大，可以承受700 mg的载荷。7.为了明确致动器的弯曲机制，我们测量了各种PUE膜的空间电荷（正常，富勒烯和CNT掺杂的薄膜），通过使用脉冲电-声学方法8.通过对分子链极性基团空间电荷的测量，我们发现分子链在阴极电极上的正负电荷所产生的电场力的作用下相互吸引。结果表明，所有PUE薄膜致动器都是向阴极方向弯曲。9.这些PUE薄膜也表现出压电效应。

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.