【作者】 薛朝华；

【导师】 汪茫； 陈红征；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2008， 博士

【摘要】 碳纳米管在生物、医药、电子、能源、国防等领域具有广泛的应用前景。然而,碳纳米管的功能化,尤其是在水中的溶解性是其迈向实际应用的关键所在。因此,碳纳米管的功能化是继碳纳米管制备与纯化之后的一大研究课题。本文着重综述了碳纳米管的水溶性改性研究进展以及水溶性碳纳米管在生物传感器领域的应用状况,并进行了以下四个方面的研究工作:（1）利用K₂S₂O₈对碳纳米管中的石墨碎片的优先氧化特性,在稀酸溶液条件下对碳纳米管进行处理以除去碳纳米管中的无定形碳杂质,设计合成了两亲性高分子水解苯乙烯-马来酸酐共聚物,采用水解苯乙烯-马来酸酐共聚物辅助剥离-离心的方法制备了聚合物包覆改性的碳纳米管,以提高碳纳米管的亲水性。并用紫外光谱、红外光谱、透射电镜、扫描电镜、热重分析、荧光光谱等手段对改性前后的碳纳米管进行了表征。结果表明,聚合物成功地包覆到碳纳米管上,所得聚合物-碳纳米管复合物具有很高的水溶性,溶解度为29.2 mg/mL,碳纳米管的净浓度高达8.7 mg/mL。（2）为了进一步提高碳纳米管的水溶性,在工作（1）的基础上,在两亲性高分子水解苯乙烯-马来酸酐共聚物中引入芘基团,以强化与碳纳米管的作用,采用含芘基水解苯乙烯-马来酸酐共聚物辅助剥离-离心的方法制备了聚合物改性的碳纳米管,提高碳纳米管的亲水性,并实现聚合物对碳纳米管的不可逆包覆。用紫外光谱、红外光谱、透射电镜、扫描电镜、热重分析、荧光光谱、时间分辨荧光光谱等手段对改性前后的碳纳米管进行了表征。结果表明,聚合物成功地包覆到碳纳米管上,并且聚合物与碳纳米管之间有很强的相互作用。所得聚合物-碳纳米管复合物具有很高的水溶性,溶解度为46.2 mg/mL,MWNTs的净浓度为7.4 mg/mL。（3）对碳纳米管进行温和氧化产生表面羟基,通过生成的羟基将柠檬酸接枝到碳纳米管表面,并将其作为接枝点使山梨醇与柠檬酸缩合聚合以实现生物相容性聚合物改性的碳纳米管。利用缩合接枝上的聚合物上羟基的弱还原性,实现金属纳米颗粒在碳纳米管表面的原位负载。并用红外光谱、透射电镜、扫描电镜、热重分析等手段对改性前后的碳纳米管进行了表征。该方法有下列优点:a.碳纳米管水溶性改性时不使用溶剂,是一种绿色环保的碳纳米管化学功能化;b.改性的碳纳米管在水中的分散性可通过加入的反应物的摩尔比进行调节;c.利用改性碳纳米管上的功能基团,如羧基和羟基可实现对碳纳米管的进一步功能化改性以制备碳纳米管基功能复合材料,如生物传感器、金属纳米催化剂。（4）将前述工作（3）中制备的改性碳纳米管应用于生物传感器技术。采用电化学循环伏安法以及电流时间法研究水溶性碳纳米管修饰电极对生物酶的固定、对生物酶的电化学生物活性的影响。结果表明,工作（3）制备的水溶性碳纳米管可以在不使用任何交联剂条件下用于固酶修饰电极。电化学测试表明,碳纳米管易于提高电极的响应电流,并且能保持酶对葡萄糖的生物催化活性。更多还原

【Abstract】 Water-soluble carbon nanotubes （CNTs） have great potential in the applications of biology, medicine, electronics, energy, and national defense etc.. The functionalization of CNTs, especially the water solubilization of CNTs is the key to the real applications. Thus, functionalization of CNTs becomes as important as their preparation and purification. This dissertation reviews the development and the current status of water solubilization of CNTs, explores the applications of water soluble CNTs in biosensors, and presents the main research contents and results which are listed as follows:1. Multi-walled carbon nanotubes （MWNTs） were treated with K₂S₂O₈ under a mild acidic condition to remove the amorphous carbon impurities. Polymer dispersant hydrolyzed poly（styrene-co-maleic anhydride） （HSMA） was synthesized and used to prepare water soluble MWNTs by an assisted exfoliation and centrifugation. Characterizations of transmission electron microscopy （TEM）, UV-vis, fluorescence spectroscopy, and thermal gravimetric analysis （TGA） showed that the as-prepared HSMA-coated MWNTs showed good dissolvability and stability in water with a high solubility of 29.2 mg/mL. The net MWNT solubility reached 8.7 mg/mL.2. In order to further improve the solubility of CNTs, HSMA were derivatized with pyrene to prepare a polymer of HSMA carrying pyrene （HPSMAP）, and used to solublize CNTs in water based upon the above-developed dispersant assisted exfoliation and centrifugation, resulting in a highly water-soluble multi-walled carbon nanotubes by irreversible noncovalent functionalization of HPSMAP. Characterizations of TEM, UV-vis, fluorescence spectroscopy, and TGA were conducted. The results showed that HPSMAP wrapped on MWNTs tightly with strong interaction. The composite of HPSMAP-MWNTs showed a high solubility of 46.2 mg/mL. The net MWNT solubility reached 7.4 mg/mL.3. Hydroxyl groups were induced by a mild oxidization of CNTs, and utilized to graft citric acid. The grafted citric were utilized to connect the polymer of citric acid and D-sorbitol by condensation through heating initiation of an anhydride intermediate without any catalysts, solvents, or harsh acid. Thus, multihydroxyl and multicarboxyl groups were introduced onto the surface of MWNTs, making MWNTs soluble in water. Ag nanoparticles were in situ loaded onto the water soluble MWNTs through the mild reduction of Ag⁺ by hydroxyl groups in aqueous solution. The as-described method has the following advantages: （a） It is a green functionalization of CNTs without using any solvents. （b） The solubility of the modified CNTs can be controlled by adjusting the mole ratio of the reactants. （c） Utilizing the hydroxyl and carboxyl groups, further functionalization of CNTs can be conducted targeting CNT-based materials for applications such as biosensors and nanocatalysis.4. Water soluble CNTs prepared by the above described condensation of citric acid and D-sorbitol were used for biosensors application. The immobilization of enzyme and the electrochemical catalysis of the immobilized enzyme on the CNT-modified electrodes were investigated. The results showed that CNTs modified by citric acid and D-sorbitol were able to immobilize enzyme firmly in the absence of any other cross-linking agent. The modified CNTs enhanced the current greatly and maintained the biocatalytic activity of enzyme well toward the reactants.更多还原