【作者】 杜飞鹏；

【导师】 解孝林；

【作者基本信息】 华中科技大学 ， 高分子化学与物理， 2008， 博士

【摘要】 由于碳纳米管(CNTs)拥有独特的结构,表现出优异的光、电、磁、力学物理性质,在生物医学和电子器件等领域拥有巨大的应用前景。尤其是水溶性碳纳米管在生物医药方面表现出了巨大潜力,更加吸引了人们关注。本文选择价廉易得的有机分子,在多壁碳纳米管(MWNTs)表面共价接枝上离子聚合物,探讨了此改性水溶性MWNTs在电化学传感器及电活性高分子制动器方面的应用。先对MWNTs进行酸化处理,利用酰胺反应在MWNTs表面引入可聚合的乙烯基。通过自由基聚合反应,将苯乙烯磺酸钠(SSS)和丙烯酸(AA)原位共聚合到MWNTs的表面,合成了聚(苯乙烯磺酸钠-丙烯酸)接枝多壁碳纳米管( P(SSS-co-AA)-g-MWNT )。傅立叶红外光谱( FTIR )、拉曼光谱( Raman Spectroscopy)、核磁共振氢谱(1H NMR)和透射电子显微镜(TEM)分析证实了聚(苯乙烯磺酸钠-丙烯酸)(P(SSS-co-AA))共价接枝在MWNTs管壁表面,形成以纳米管为核、P(SSS-co-AA)为壳的核壳结构,包覆层厚度在7-12nm之间,P(SSS-co-AA)的接枝含量为82.3%。P(SSS-co-AA)-g-MWNT具有良好的水溶性,溶解度为4mg/mL。利用此水溶性MWNTs修饰玻碳电极制成电化学传感器,修饰的电极具有电子快速转移能力、强的催化能力和电化学活性。用该电化学传感器检测生物分子时,尿酸(UA)、多巴胺(DA)和5-羟基色胺(5-HT)分别有较好的电化学响应,且能同步检测多巴胺和5-羟基色胺。以水溶性MWNTs为模板,在其表面组装Ag纳米粒子,形成Ag@MWNT纳米复合物。通过控制还原剂的添加量,组装的Ag颗粒尺寸能控制在2-4nm之间,且Ag@MWNT在水中具有良好的分散性。复合物修饰的玻碳电极具有较强的催化能力,能检测溶液中的溶解氧和双氧水。通过热交联和戊二醛交联,制备了PVA/P(SSS-co-AA)离子交换膜(IEM),并优化实验条件。当PVA与P(SSS-co-AA)的质量比为2:1时,IEM有较好的力学性能、离子交换容量和吸水率。P(SSS-co-AA)-g-MWNT与PVA/P(SSS-co-AA) (w/w 2:1)基体具有很好的相容性,能均匀的分散于基体中。与未添加P(SSS-co-AA)-g-MWNT的IEM相比,添加P(SSS-co-AA)-g-MWNT的IEM力学性能和电导率得到明显改善。当P(SSS-co-AA)-g-MWNT的添加量为20%时,离子交换膜的杨氏模量从288.70增加到620.46 MPa,电导率从10-13增大到10-4 Scm-1。以离子交换膜为中间层,两面镀上金属Au,制备了三明治结构的制动器。在直流电场(1-5V)的驱动下,制动器能向阳极发生弯曲变形。当采取频率为0.25Hz、电压为±1.5V的方波驱动时,掺杂5%、10%和20% P(SSS-co-AA)-g-MWNT的制动器偏转位移的振幅均在13 mm以上。同时,随着P(SSS-co-AA)-g-MWNT添加量的增加,制动器的松弛现象得到明显改善,对电场的灵敏性也得到提高。用P(SSS-co-AA)-g-MWNT膜取代金属Au作为电极层,制备了新型结构的制动器。在直流电场驱动下,制动器向阳极作弯曲变形运动。当在频率为0.25Hz、电压为2V的方波电压驱动下,制动器作周期性弯曲运动,偏转位移最大振幅为1 mm,并且随着电压的增大偏转位移振幅增大。通过SEM观察,功能化纳米管组成的MWNTs片与离子交换膜具有强的界面粘结性,在循环弯曲变形时不易剥离。MWNTs片中纳米管的网络连接和多孔结构,能阻止水分解时所产生的气体对电极层的破坏。在0.25Hz、±2.0V方波电压驱动下、经过3,000次循环操作,偏转的最大位移幅度仅减少大约10%;而每天循环操作200次,持续三个月后制动器的偏转位移几乎没有衰减,该制动器具有较长的使用寿命。更多还原

【Abstract】 Carbon nanotubes (CNTs) are extremely promising for applications in materials science and medicinal chemistry, due to their extraordinary optical, electronic, thermal, mechanical and chemical properties. Especially, water-soluble carbon nanotubes (CNTs)-based composites have received much attention for investigations in the area of potential biological applications and environmentally compliant productions. But the defects of their insolubility and entanglements have imposed great limitations to the application and development of CNTs. The poor solubility of nanotubes in most solvents and matrices rendered a difficult processing ability, and the excellent properties of individual nanotube cannot show high efficiency in the matrices. How to obtain water-soluble CNTs is becoming a great challenge, which determined the commercial viability of the large-scale CNT processing. The most common way to overcome this above is the chemical modification of CNTs by oxidation followed by organic modification with hydrophilic substances.In the present dissertation, the synthesis of ionic polymer covalently modified CNTs, as well as the structure and the electroactive properties of the modified CNTs have been mainly studied. The organic small molecules with functional groups are preliminarily grafted onto the CNT surfaces via amidation to generate CNT-supported macroinitiators. Ionic polymer is then covalently grafted on the surface of CNTs via free radical in-situ polymerization of monomers and finally silver (Ag) nanoparticles are assembled on the surface of CNTs via water-soluble CNTs as template. The electrochemistry of water-soluble CNTs and Ag/CNTs was investigated. The actuation behaviors of ion-exchange membrane with water-soluble CNTs have been also discussed. Water-soluble poly (sodium styrene sulfonate-co-acrylic acid) (P(SSS-co-AA)) grafted CNTs (P(SSS-co-AA)-g-MWNT) have been successfully synthesized by an in-situ free radical copolymerization of sodium styrene sulfonate and acrylic acid in the presence of CNTs terminated with vinyl groups. P(SSS-co-AA)-g-MWNT showed a core-shell structure with a polymer layer thickness of 7-12 nm as shell and nanotube as core, and the grafting content of polymer was 82.3 wt.%. P(SSS-co-AA)-g-MWNT has good solubility and stable dispersibility in water with 4 mg/mL of dissolubility. The electrochemical sensor based on P(SSS-co-AA)-g-MWNT has strong catalytic ability, high electrochemical activity and fast electronic transfer capability. Low content of uric acid (UA), dopamine (DA) and 5-hydroxytryptamine (5-HT), respectively, can be detected by this sensor. It is very interesting that P(SSS-co-AA)-g-MWNT can detect the mixture of DA and 5-HT simultaneously.Ag and CNTs composite (Ag@MWNT) has been successfully synthesized by in-situ reducing Ag ion on the surface of nanotube with water-soluble CNTs as template. Ag crystal is composed of fcc unit cell structure with a =0.408 nm and has a narrow size distribution among 2-4 nm and adheres firmly on the surface of nanotube. The electrochemical sensor based on Ag@MWNT had good catalyst ability to the low concentration of dissolved oxygen (O2) and peroxide hydrogen (H2O2).Reinforced ion-exchange membrane (IEM) has been prepared by doping CNTs into the matrix of poly (vinyl alcohol) (PVA) and P(SSS-co-AA), generating good water-uptake and ionic exchange capability. Ionic polymer-functional CNTs had well-dispersed and was well good compatible in/with the matrix, resulting improve mechanical strength and conductivity of IEM.Electroactive actuators have been consisted of sandwich structure by sputtering gold (Au) on the two sides of IEM. All the actuators with four different contents of CNTs have more than 10 mm displacement of tip deflection under low square wave potential of±1.5 V with a frequency of 0.25 Hz. With the increasing of content of CNTs doped, the relaxation of actuator was gradually disappeared and the sensitivity of actuator to the electric filed increases.A novel actuator has been prepared with functional CNTs mat which served as electrode lays. The actuator shows maximum deflection displacement of 1 mm and 3 mm driven by±2.0 V or±3.0 V potential of square wave with a frequency of 0.25 Hz, respectively. Compared with Au metal as electrode, the CNTs mats improve the cycle life of the actuator with the continuous actuation of 3,000 cycles and the actuator is able to have a three months cycle life if driven 200 strokes each day.更多还原