石墨烯纤维的可控制备与应用研究

发布时间：2018-07-23 18:56

【摘要】：石墨烯作为二维碳基纳米材料,只有一个原子的厚度,具有优异的力学、电学、热学和光学性能,基于石墨烯制备的一维、二维和三维材料在透明导电薄膜、储能材料、催化剂载体、气敏材料、单分子探测器等方面具有极为广阔的应用前景。其中石墨烯及其复合物的一维纤维材料,因其具有高强度、高导电、柔性可编织和简单易加工的特点,适合于制备超轻质导线、柔性可穿戴器件、智能织物等。目前多数报道的关于石墨烯纤维的研究主要着眼于提高纤维的断裂强度,但是由于石墨烯纤维的脆性断裂,其拉伸应变往往较低,其柔性也有待提高。本文所研究的具有独特螺旋结构的石墨烯纤维,能够同时获得高强度和高弹性的特征,有助于进一步开发高性能的可拉伸、可穿戴器件。本文采用改进hummers法,运用硫酸-磷酸-高锰酸钾体系制备了高纯氧化石墨烯。利用流延法制备了柔性透明的氧化石墨烯薄膜,用不同还原方法对其进行还原,并研究还原前后的形态和性能变化,发现经45%的氢碘酸还原后,能最大程度的保持石墨烯薄膜在还原前的表面形貌。在聚四氟乙烯基底上制备的大面积氧化石墨烯薄膜,经自然干燥后,裁剪成不同宽度的条带,并采用干法纺丝,借助于水汽调节氧化石墨烯薄膜的湿度,将条带纺织成具有较长连续螺旋结构的不同直径的氧化石墨烯螺旋纤维,且纤维的螺旋结构均匀、螺旋倾角一致、表面光滑,还具有柔性可拉伸的特点。将氧化石墨烯螺旋纤维经氢碘酸还原后得到的导电石墨烯螺旋纤维,保持其螺旋结构不变,且纤维表面光滑连续。石墨烯螺旋纤维具有较好的机械性能,其强度达12 MPa,最大断裂应变达60%,在20%的拉伸循环下表现出良好弹性恢复性能。拉伸过程中电阻呈规律性变化,随着应变的增加,电阻呈线性减小。经过多次循环后,这种变化规律依然稳定。探索了石墨烯螺旋纤维做为可拉伸温度传感器和电抽吸的应用研究。测试了纤维的电阻随温度的变化,随着温度的增加电阻减小,主要是由于石墨烯的半导体行为特征。发现在300o C的高温和应变范围在0%~50%的不同拉伸应变下,螺旋纤维显示出稳定的热学性能,具有用作柔性热敏器件的潜在价值。导电的石墨烯螺旋纤维内部具有轴向贯通微通道和石墨烯疏水的特点,由其制备的电抽吸具有良好的可控开关性能,激发的阈值电压为-0.8V,理论计算和实际测试得到的通道尺寸一致,约为100 nm,对液体抽吸至饱和时,能吸收是自身重量6倍的水。为进一步提高石墨烯螺旋纤维的性能,本文提出了制备氧化石墨烯-碳纳米管复合薄膜的新方法,不同于以往机械搅拌制备复合薄膜的方法,该方法能一步制备均匀交替叠加的氧化石墨烯-碳纳米管复合薄膜。基于该复合薄膜制备的氧化石墨烯-碳纳米管复合螺旋纤维在对水、乙醇和丙酮等液体的吸附和脱附过程中,能产生良好的致动效果,能拉起是自身重量约300倍的重物。经氢碘酸还原后得到的石墨烯-碳纳米管复合螺旋纤维的最大断裂强度达135 MPa,最大断裂应变达130%,分别是纯石墨烯螺旋纤维的10倍和2倍;其作为温度传感器,随温度变化的线性更好,响应度更高,是纯石墨烯螺旋纤维的7倍;利用编织方法,制备了基于该种复合螺旋纤维编织网的可拉伸、柔性可弯曲的超级电容器具有良好的电化学性能,其比电容在100 m V/s扫速下为44 m F/cm2。
[Abstract]:As a two-dimensional carbon based nanomaterial, graphene has only one atomic thickness, with excellent mechanical, electrical, thermal and optical properties. The one-dimensional, two-dimensional and three-dimensional materials based on graphene have a very broad application prospect in transparent conductive films, energy storage materials, catalyst carriers, gas sensitive materials, single molecule detectors and so on. The one-dimensional fiber materials of graphene and its composites have the characteristics of high strength, high conductivity, flexible weaving and easy processing. It is suitable for the preparation of ultralight wire, flexible wearable device and intelligent fabric. Most of the reports about graphene fiber are mainly focused on improving the fracture strength of the fiber, but because of it, The brittle fracture of graphene fibers is often low and its flexibility needs to be improved. The unique spiral structure of graphene fibers in this paper can simultaneously obtain high strength and high elastic characteristics and help to further develop high performance tensile and wearable devices. In this paper, the improved Hummers method and sulfuric acid are used in this paper. The high pure oxygen fossil Mexico was prepared by the phosphoric acid Potassium Permanganate system. The flexible and transparent graphene oxide film was prepared by the casting process. It was reduced by different reduction methods. The changes of morphology and properties before and after reduction were studied. It was found that after reduction of 45% hydroiodic acid, the surface of graphene film could be kept to the surface before reduction to the maximum. The large area of graphene oxide films prepared on the polytetrafluoroethylene base are cut into strips of different width after natural drying and dry spinning, and the strips are woven into different diameters of graphite oxide spiral fibers with a long continuous spiral structure by using water vapor to adjust the humidity of the graphene oxide film. The spiral structure of the spiral is uniform, the spiral inclination is consistent, the surface is smooth, and it has the characteristic of flexible and extensible. The spiral fiber of the graphite oxide spiral fiber is reduced by the reduction of the hydroiodic acid. The spiral structure of the spiral fiber is kept constant and the surface of the fiber is smooth and continuous. The spiral fiber of graphene has good mechanical properties and its strength is 12. MPa, the maximum fracture strain is 60%, and the elastic recovery performance is good under the 20% tensile cycle. The resistance assumes a regular change during the stretching process and the resistance linearly decreases with the increase of strain. After several cycles, the change law is still stable. The resistance of the fiber is measured with the change of temperature. The resistance decreases with the increase of temperature, mainly due to the behavior characteristics of the graphene. It is found that the high temperature and strain range of 300O C at different tensile strains of 0%~50% show stable thermal properties, and have the potential price for the flexible thermosensitive devices. The conductive graphene spiral fiber has the characteristics of the axial penetration microchannel and the hydrophobicity of the graphene. The electrical suction prepared by it has a good controllable switching performance and the threshold voltage is -0.8V. The theoretical calculation and the actual test have the same channel size, about 100 nm. When the liquid is sucked to saturation, it can absorb itself. In order to further improve the properties of graphene spiral fibers, a new method of preparation of graphene oxide carbon nanotube composite films is proposed in this paper, which is different from the preparation of composite films by mechanical agitation. This method can be used to prepare homogeneous and alternate superimposition of oxidizing stone carbon nanotube composite thin films. Based on this composite thin film, the composite thin film can be prepared. In the process of adsorption and desorption of water, ethanol and acetone, the film made of graphene oxide carbon nanotube composite spiral fiber can produce good actuation effect and can pull up a weight about 300 times of its own weight. The maximum fracture strength of graphene carbon nanotube complex spiral fiber obtained by hydrogen iodic acid reduction reaches 135 MPa, and the maximum strength is up to 135. The strain of the large fracture is 130%, which is 10 times and 2 times that of the pure graphene spiral fiber. As a temperature sensor, its linearity is better with the temperature change, the response degree is higher than that of the pure graphene spiral fiber, which is 7 times that of the pure graphene spiral fiber. The electrochemical performance is 44 m F/cm2. at a specific capacitance of 100 m V/s.
【学位授予单位】：郑州大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ342.74

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