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

本论文的研究成果总结如下：1.利用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移动器件中。2.利用PUE薄膜的电致伸缩效应制作了单晶片结构的驱动器，并在两层薄膜表面蒸发相同厚度(200 Nm)的金属电极。3.由于这些驱动器工作在1KV以上的高压下，我们在PUE中掺杂了碳纳米管(CNTs)的衍生物来控制薄膜的分子结构，从而使驱动器可以在较低的电压下工作。4.掺碳纳米管的PUE驱动器的弯曲位移随电场的平方而变化。PUE致动器的所有样品都沿着阴极的方向弯曲，与金属材料无关。5.掺入碳纳米管的致动器弯曲较大，工作电压为300V，且弯曲位移强烈依赖于碳纳米管的羟基数目。6.掺入碳纳米管的致动器的激发力与外加电压成正比，且与薄膜厚度显著相关。7.为了明确驱动器的弯曲机理，我们用脉冲电声方法测量了不同类型的PUE薄膜(正常薄膜、富勒醇薄膜和碳纳米管掺杂薄膜)的空间电荷。8.基于分子链极性基团的空间电荷测量发现，由于阴极上的正负电荷作用，分子链相互吸引。结果表明，所有的PUE薄膜驱动器都是沿着阴极的方向弯曲的。9.PUE薄膜也表现出了压电性。

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.