原位生长碳纳米管增强复合材料的研究现状与展望

碳纳米管优异的力学、热学和电学性质使其成为高性能复合材料的新型增强体,但难以分散,限制了其进一步应用.CVD法原位生长碳纳米管可有效解决碳纳米管在复合材料中的分散问题,是制备碳纳米管增强复合材料的理想方法.综合分析了国内外原位生长碳纳米管增强复合材料的研究状况,指出了存在的问题及以后的发展趋势.     

碳纳米管/聚苯胺复合材料的制备及电性能

利用超声波将多壁碳纳米管(CNTs)分散于苯胺盐酸溶液体系中,以过硫酸铵((NH4)2S2O8)为氧化剂,原位聚合法制备碳纳米管/聚苯胺纳米复合材料(CNTs/PANI)。采用扫描电子显微镜(SEM)、傅立叶变换红外光谱(FT-IR)、四探针电导率测试仪对复合材料进行表面观察、结构测定和电性能表征。结果表明,复合材料为核-壳结构,碳纳米管和聚苯胺间存在相互作用,其电导率随碳纳米管含量的增加而增加。     

碳纳米管的力学性能及聚合物/碳纳米管复合材料

综述了碳纳米管（CNTS）的制备方法、结构与力学性能的关系，介绍了近年来聚合物／碳纳米管复合材料的最新进展，对现有聚合物／碳纳米管复合材料的制备方法存在的主要问题进行了分析。     

碳纳米管增强铝基复合材料制备技术进展

通过对比工艺方法和材料力学性能,总结了球磨混合、大塑性变形、热喷涂、纳米尺度分散、原位生成以及片状粉末冶金等主要制备技术的优缺点,并结合当前制备过程中的主要问题,讨论了碳纳米管/铝复合材料未来的发展方向。     

碳纳米管/羟基磷灰石复合材料的制备及表征

以含钴介孔分子筛为催化剂、乙醇为碳源, 采用CVD法制备碳纳米管(CNTs)。通过原位合成法制备一系列不同碳纳米管含量的碳纳米管/羟基磷灰石(CNTs/HA)复合材料。分别采用XRD、FTIR、TEM、N₂吸附-脱附和Raman光谱等分析手段, 对所合成CNTs/HA复合材料的晶相、结构、形貌和比表面积等进行了表征。同时研究了碳纳米管的添加量对所合成CNTs/HA复合材料形貌的影响。XRD与Raman结果表明, 所得CNTs/HA复合粉体中仅有CNTs与HA两种物相, 纯度较高, 结晶度较好; TEM结果显示, CNTs/HA复合材料中CNTs表面均匀包裹着一层纳米级的针状HA晶粒, 两者形成了较强的界面结合, 且当CNTs与HA的质量比为3:17时, CNTs与HA形成最佳结合状态; N₂吸附-脱附表征结果表明, 与HA的比表面积相比, CNTs/HA复合材料具有较高比表面积。     

多糖/金属有机框架(MOFs)复合气凝胶的制备及应用进展

气凝胶材料是一类具有三维纳米结构的多孔材料,在航空航天、石油化工、环保工程、建筑工程、化学催化、医药卫生等领域表现出广泛的应用价值,自问世以来一直深受人们的关注.由纤维素、壳聚糖、海藻酸等多糖制备得到的气凝胶材料不仅能够保持传统气凝胶高孔隙率、大比表面积、低密度的特点,还具备了天然高分子可再生、可降解、生物兼容性好的优点,成为了当前的热门材料之一.金属有机框架(MOFs)是一类由金属节点以及有机配体通过配位作用组装形成的多孔框架材料,在吸附、催化、传感、载药等领域都表现出巨大的应用潜力.随着对材料应用功能、加工性能、循环使用性能等要求的提升,近年来人们对多糖/MOFs复合气凝胶材料的研究兴趣逐渐高涨.自2016年第一例纤维素纳米晶/MOFs复合气凝胶材料被报道以来,研究人员尝试了多种不同的多糖以及MOFs组合,制备了不同类型的多糖/MOFs复合气凝胶材料,并探索了它们在不同领域的应用.本文首先总结了多糖/MOFs复合气凝胶材料的三种常见制备策略:(1)将预先制备好的MOFs与多糖直接混合制备复合气凝胶;(2)在多糖分子表面原位生成MOFs之后再制备复合气凝胶;(3)在已制备好的多糖气凝胶中原位生成MOFs再制备复合气凝胶.通过相应的实例详细介绍了这些制备方法的特点,然后分别介绍了多糖/MOFs复合气凝胶材料在不同领域中的应用情况,最后针对当前该领域研究存在的不足以及面临的问题提出了解决方法并展望了未来可能的发展方向.     

碳纳米管增强聚合物基复合材料进展

碳纳米管具有超常的力学性能、电性能和热性能,碳纳米管增强复合材料被认为是最有潜力的结构功能一体化复合材料.从阻碍碳纳米管复合材料高性能化的主要因素、碳纳米管复合材料增强体、碳纳米管复合材料成型工艺、碳纳米管复合材料性能等方面讨论了碳纳米管聚合物基复合材料的研究现状.     

有机化学合成法制备碳纳米管/聚苯胺复合材料

通过有机化学合成法使苯胺单体接枝到碳纳米管表面,然后再经化学原位聚合法制备碳纳米管/聚苯胺复合材料.用傅立叶变换红外光谱和扫描电子显微镜对复合材料的成分和形貌进行表征.用循环伏安法、恒流充放电和电化学阻抗等电化学测试手段来表征复合材料的电化学性能.研究结果表明,所制备的复合材料比容量可达到152F/g(有机电解液),显著高于同样条件下的纯聚苯胺、纯碳纳米管及由原位化学聚合法所制备碳纳米管/聚苯胺复合材料的电化学容量(65、25、80F/g),显示出良好的应用前景.     

磁性金属有机复合材料的合成与应用

金属有机框架材料(MOFs)是一种将金属离子中心与有机配体通过配位键结合起来的一类具有网格结构的材料。由于金属离子以及有机配体的多样性,MOFs的结构也具有多样性。磁性金属有机复合材料是一种新型的复合材料,既结合了MOFs的网状结构及结构多变性的优点,又结合了磁性材料易于分离且可重复利用的特性,使得这种材料在药物载体、多相催化、选择吸附等多种方面都有着较为广泛的应用。以经典的几类MOFs为分类依据,研究了它们与磁性材料结合形成新型复合材料的方法,同时概括了这些新型复合材料在不同领域的应用,最后提出了该材料目前所存在的问题,并对今后的研究方向进行了展望。     

碳纳米管/高分子复合材料的制备及应用研究进展

将碳纳米管掺杂到聚合物母体中形成的碳纳米管/高分子复合材料具有良好的力学、导电和非线性光学性质。在聚合物中添加少量碳纳米管可以明显改变聚合物的结晶和形貌。大量研究表明,这些复合材料在诸如太阳能电池、有机发光器件、光限幅、光学开关、防护涂料以及人造肌肉等方面具有潜在的实际应用价值。文中介绍了碳纳米管/高分子复合材料的制备方法及其在高科技领域中的应用潜能。     

Glucose biosensor based on carbon nanotube epoxy composites

A novel glucose biosensor based on a rigid and renewable carbon nanotube (CNT) based biocomposite is reported. The biosensor was based on the immobilization of glucose oxidase (GOx) within the CNT epoxy-composite matrix prepared by dispersion of multi-wall CNT inside the epoxy resin. The use of CNT, as the conductive part of the composite, ensures better incorporation of enzyme into the epoxy matrix and faster electron transfer rates between the enzyme and the transducer. Experimental results show that the CNT epoxy composite biosensor (GOx-CNTEC) offers an excellent sensitivity, reliable calibration profile, and stable electrochemical properties together with significantly lower detection potential (+0.55 V) than GOx-graphite epoxy composites (+0.90 V; difference deltaE = 0.35 V). The results obtained favorably compare to those of a glucose biosensor based on a graphite epoxy composite (GOx-GEC).     

Investigation of nanotube length effect on the reinforcement efficiency in carbon nanotube based composites

The main goal of this research is to study the tensile behavior of embedded short carbon nanotubes (CNTs) in a polymer matrix in presence of van der Waals (vdW) interaction as inter-phase region. A 3D finite element model of a unit cell consisting of capped carbon nanotubes, inter-phase and surrounding polymer is built. The unit cell is subjected to tensile load case to obtain longitudinal Young’s modulus of the investigated cell. A parametric study is carried out to investigate the effect of CNT’s length on reinforcement. It is observed that improvement in the Young’s modulus of CNT-composite is negligible for lengths smaller than 100 nm and saturation takes place in larger lengths on the order of 10 μm. Furthermore, a comparison between results obtained for short carbon nanotubes and long carbon nanotube is presented. The efficient length of CNT in form of (10, 10) is obtained at the order of 10 μm. Finally, it was shown that direct use of micromechanics equations for short fibers will overestimate the stiffness. However, employing effective stiffness of equivalent fiber comprising of CNT and its inter-phase instead of high modulus of CNT will lead us to more appropriate results, which are in an acceptable agreement with conventional semi-empirical micromechanics equations.     

Scalable fabrication of immunosensors based on carbon nanotube polymer composites

In this work we present the fabrication and characterization of immunosensors based on polystyrene (PS)-multiwalled carbon nanotube (MWCNT) composites. The electrochemical properties of the sensors have been investigated and show that the surface area is increased upon addition of the MWCNT-PS layer. Furthermore, a plasma activation process is used to partially remove the PS and expose the MWCNTs. This results in a huge increase in the electrochemical area and opens up the possibility of binding biomolecules to the MWCNT wall. The MWCNTs have been functionalized covalently with a model antibody (rabbit IgG). The biosensors have been tested using amperometric techniques and show detection limits comparable to standard techniques such as ELISA.     

Viscoelasticity in carbon nanotube composites

Polymer composites reinforced by carbon nanotubes have been extensively researched for their strength and stiffness properties. Unless the interface is carefully engineered, poor load transfer between nanotubes (in bundles) and between nanotubes and surrounding polymer chains may result in interfacial slippage and reduced performance. Interfacial shear, although detrimental to high stiffness and strength, could result in very high mechanical damping, which is an important attribute in many commercial applications. We previously reported evidence of damping in nanocomposites by measuring the modal response (at resonance) of cantilevered beams with embedded nanocomposite films. Here we carry out direct shear testing of epoxy thin films containing dense packing of multiwalled carbon nanotube fillers and report strong viscoelastic behaviour with up to 1,400% increase in loss factor (damping ratio) of the baseline epoxy. The great improvement in damping was achieved without sacrificing the mechanical strength and stiffness of the polymer, and with minimal weight penalty. Based on the interfacial shear stress (approximately 0.5 MPa) at which the loss modulus increases sharply for our system, we conclude that the damping is related to frictional energy dissipation during interfacial sliding at the large, spatially distributed, nanotube-nanotube interfaces.     

Three-dimensional carbon nanotube based polymer composites for thermal management

In this study, the porous multiwall carbon nanotube (MWCNT) foams possessing three-dimensional (3D) scaffold structures have been introduced into polydimethylsiloxane (PDMS) for enhancing the overall thermal conductivity (TC). This unique interconnected structure of freeze-dried MWCNT foams can provide thermally conductive pathways leading to higher TC. The TC of 3D MWCNT and PDMS composites can reach 0.82 W/m K, which is about 455% that of pure PDMS, and 300% higher than that of composites prepared from traditional blending process. The obtained polymer composites not only exhibit superior mechanical properties but also dimensional stability. To evaluate the performance of thermal management, the LED modulus incorporated with the 3D MWCNT/PDMS composite as heat sink is also fabricated. The composites display much faster and higher temperature rise than the pristine PDMS matrix, suggestive of its better thermal dissipation. These results imply that the as-developed 3D-MWCNT/PDMS composite can be a good candidate in thermal interface for thermal management of electronic devices.     

碳纤维增强铜基复合材料制备方法研究进展

综述了碳纤维增强铜基复合材料的主要制备方法及其发展现状,重点讨论了粉末冶金法、热压扩散烧结法、熔渗法、PVD法、CVD法及电镀法等常用制备工艺的原理及特性,分析了不同制备方法的优缺点及适用领域,提出了现有方法中存在的问题,并展望了碳纤维增强铜基复合材料的发展趋势及在输变电领域的应用前景。     

介孔材料的制备及其在碳纳米管合成中的应用研究

本文综述了介孔材料的制备方法,重点介绍了以介孔材料为模板或为载体制备碳纳米管的方法,总结了催化剂、反应温度和时间等因素对制备碳纳米管的影响.介绍了碳纳米管在介孔中的生长机理.最后探讨了该研究领域亟待解决的问题以及今后可能的发展前景.     

Continuous carbon nanotube reinforced composites

Carbon nanotubes are considered short fibers, and polymer composites with nanotube fillers are always analogues of random, short fiber composites. The real structural carbon fiber composites, on the other hand, always contain carbon fiber reinforcements where fibers run continuously through the composite matrix. With the recent optimization in aligned nanotube growth, samples of nanotubes in macroscopic lengths have become available, and this allows the creation of composites that are similar to the continuous fiber composites with individual nanotubes running continuously through the composite body. This allows the proper utilization of the extreme high modulus and strength predicted for nanotubes in structural composites. Here, we fabricate such continuous nanotube polymer composites with continuous nanotube reinforcements and report that under compressive loadings, the nanotube composites can generate more than an order of magnitude improvement in the longitudinal modulus (up to 3,300%) as well as damping capability (up to 2,100%). It is also observed that composites with a random distribution of nanotubes of same length and similar filler fraction provide three times less effective reinforcement in composites.     

Polyazomethine/carbon nanotube composites

Composites were synthesized by “in-situ” polymerization of polyazomethine, a liquid crystal polymer (LCP), in presence of multi-walled carbon nanotubes (MWNTs) previously dispersed in one of the employed monomers. Fiber processing was carried out by extrusion from the composites containing 1 and 10 wt.% of MWNTs at the mesophase temperature. We have observed that the typical highly oriented internal fibrillar structure can be significantly disrupted by increasing the nanotube content in the composite fibers. Evidences of MWNT alignment were found in the studied LCP/MWNT composites.