温度敏感材料，又称为热敏材料，是最常见的一类智能材料。其中，热敏电 阻是热敏材料中最典型的一类，独特的随温度变化的电学信号使其易于制作成敏 感电子元件，在温度探测与控制、电路的过载保护等自动化控制领域都发挥着重 要作用，关于热敏电阻的研究有助于合理利用能源与开发新型的智能材料。目前， 智能建筑材料、智能电源开关、药物的存储与运输、微生物的实验研究等一系列 新兴领域对室温范围内的热敏材料有着迫切的需求，因此研究开发室温范围内的 热敏材料有着重要的现实意义。近年来，利用复合材料的固-液相变设计室温范 围内热敏开关材料的概念被提出，在制造成本、可操作性等多方面都极具应用优 势，受到研究者们的关注。 本论文首先通过化学功能化的方式对碳黑进行改性，成功在碳黑表面修饰了 油酸分子，并将功能化后的碳黑分散于十六烷基体中，得到了稳定的碳黑/十六 烷相变开关复合材料。对该复合材料进行了电导率与热导率测试，结果表明复合 材料在 18 ℃附近呈现出了明显的开关效应，电导率与热导率相应的最大开关比 分别可达 4 个数量级和 3.5 倍，并针对油酸功能化在提升复合材料开关性能方面 的重要作用进行了讨论。 其次，本论文对碳纳米管/十六烷相变开关复合材料展开了研究，提出了一 种新的碳纳米管在烷烃等非极性溶剂中的分散方法。利用化学改性与物理修饰相 结合的思路，将强酸氧化后的碳纳米管用十六醇作为分散剂，可稳定分散于十六 烷中。结果证明，这种分散方式比其他的方法都更有利于提升复合材料的开关性 能与稳定性。碳纳米管/十六烷复合材料的直流电导率在温度变化时也表现出良 好的开关特性，电导率开关比最高可达将近 6 个数量级，是目前同类型材料中最 高的。此外，文中也对变温速率、碳纳米管混酸处理的时间、分散剂用量等一些 影响因素进行了探讨，结果表明变温速率越低，开关比越高。最合理的碳纳米管 混酸处理的时间和分散剂用量分别为 12-24 h 和 0.5-3 wt%。 最后，本论文对这类碳纳米管相变开关复合材料的定形化展开探索。利用有 机小分子的凝胶作用将十六醇作为凝胶剂，在十六烷中形成有机凝胶网络，并在 十六醇添加量较高时得到了室温下呈固态外形的复合材料，实现了对十六烷基复 合材料的室温定形化。这种定形化处理在保证电导率开关比性能的同时也能保证对液体的封装效果，具有明显的应用优势。在保证复合材料外形无明显变化的情 况下，室温范围内的电导率开关比可达 3-4 个数量级。在此基础上，本论文对定 形化的相变开关复合材料做了初步的应用尝试。通过碳纳米管/十八醇/二十烷的 复合材料实现对太阳光的光-热-电的复合转换，证明了开关材料在实际应用中的 良好表现。样品在太阳光辐照下引起表面温度上升，进而导致材料内部的结构变 化，相应测量的电流在二十烷的相变温度 36 ℃附近约有 2500 倍的变化，这种将 温度敏感材料与光热转换相结合的应用可以极大地拓展该类复合材料的应用范 围和实用价值。

Temperature sensitive materials, also known as heat sensitive materials, are one of the important smart materials. Thermistor is the most typical materials among them. The unique electrical conductivity sensitivity of thermistor to temperature change makes it easy to fabricate sensitive electronic components. It plays an important role in the field of temperature detection, temperature control, circuit overload protection and so on. Research on thermistors helps us use energy rationally and develop new smart materials. At present, many emerging fields such as smart building materials, intelligent power switches, storage and transportation of drugs, and experimental research on microorganisms have an urgent need for temperature-sensitive materials in the room temperature range. Therefore, it is very important to research and develop room- temperature sensitive materials. In recent years, the concept of utilizing solid-liquid phase change of composite materials has been proposed to design a thermal switch material in the room temperature range. It has great potential application, and has attracted the attention of researchers. In this thesis, carbon black/hexadecane switching composite was firstly developed. Carbon black was modified by chemical functionalization, and oleic acid was successfully modified on the surface of the carbon black. The functionalized carbon black was dispersed in the hexadecane stably to obtain carbon black/hexadecane phase change switch composite. Electrical conductivity and thermal conductivity tests were carried out. The results show that the composite exhibits a significant switch effect around 18 °C. The maximum switch ratio of electrical conductivity and thermal conductivity is 4 orders of magnitude and 3.5 times, respectively. The important role of oleic acid functionalization in improving the switching performance was also discussed. Secondly, carbon nanotube/hexadecane phase change switch composites were studied, and a new method for the dispersion of carbon nanotubes in non-polar solvents such as alkanes was proposed. By combining chemical modification and physical modification, the oxidized carbon nanotubes can be dispersed into hexadecane stably by using hexadecanol as the dispersant. Experiment results show that this kind dispersion strategy is more beneficial to improve switching performance and stability of composite materials than other methods. The direct current conductivity of carbon nanotube/hexadecane composites also shows good switching characteristics when temperature changes. The conductivity switch ratio is up to nearly six ordersof magnitude, which is the highest among the same types of materials. In addition, some factors such as temperature ramping rate, oxidation time of carbon nanotube and dispersant dosage are also discussed. The results show that the lower the temperature change rate, the higher the switching ratio. The most reasonable oxidation time for carbon nanotubes and the additive amount of dispersant are 12-24 h and 0.5-3 wt%, respectively. Finally, this thesis explored the shape-stabilization of carbon nanotube phase change switching composites. By the gelation of small organic molecules of hexadecanol, an organogel network was formed in hexadecane. The composite with solid shape at room temperature was obtained when the amount of hexadecanol was increased. This shape-stabilization treatment can realize the conductivity switching effect in solid state, which has more advantages in application. The conductivity switch ratio of these materials in the room temperature range can be up to 3-4 orders of magnitude without any significant change in the shape. Based on these materials, a preliminary application was carried out by the shape-stable phase change switch composite. The conversion of light-heat-electricity to sunlight is realized in the carbon nanotubes/octadecanol/eicosane composites, which proves the good performance of switch material in practical applications. The surface temperature of sample increased under the irradiation of sunlight, which leads to the structural change inside the material. The measured current changes about 2500 times around the phase transition temperature of eicosane at 36 °C. The combination of photothermal conversion and temperature sensitive materials can greatly expand the applications of the composite.