氧化还原法制备石墨烯及其表征

采用改进的Hummers法氧化处理石墨粉制得氧化石墨,利用超声波作用将氧化石墨剥离,得到均匀分散的氧化石墨烯胶状悬浮液,然后在水合肼的还原作用下得到石墨烯。采用SEM、XRD以及Raman光谱对样品进行了形貌、结构以及谱学的表征分析。考察了还原过程中温度对还原效果的影响,以及中性条件下、碱性条件下水合肼用量对还原效果的影响。     

氧化石墨烯/聚合物复合材料的研究进展

介绍了氧化石墨烯及其改性,氧化石墨烯/聚合物的制备方法。优异的性能使复合材料应用广泛,主要用在超级电容器、燃料电池、阻燃材料、生物医学等领域。同时提出了复合材料研究中的一些问题,如氧化石墨烯的改性及复合材料的实际应用。     

氧化石墨烯及其聚合物复合材料制备的研究进展

石墨烯是一种具有单层蜂窝状二维网格结构的新型材料,具有优异的力学、化学性能。氧化石墨烯(GO)作为氧化-还原法制备石墨烯的中间体,具有较高的比表面积以及石墨烯所不具备的丰富官能团。鉴于官能团的存在,GO具有优良的化学修饰性能,以此可制备性能更高的或具备新性能的GO/聚合物复合材料。文中综述了氧化石墨烯的结构、性能及制备方法,主要介绍了制备GO的Hummers法,比较了GO/聚合物复合材料的不同制备方法,列举了复合材料的性能特点,最后对GO复合材料制备方法的发展和GO/聚合物复合材料的应用前景进行了展望。     

氧化石墨烯复合材料的研究进展

氧化石墨烯是一种性能优异的新型碳材料,具有较高的比表面积和表面丰富的官能团.简单介绍了氧化石墨烯的制备方法,重点阐述了氧化石墨烯复合材料的研究进展,包括聚合物类复合材料以及无机物类复合材料的合成方法、性能以及应用领域,展望了氧化石墨烯的制备及其复合材料今后的研究方向,提出少引入或者不引入杂离子的新型绿色环保的制备方法是氧化石墨烯制备的发展方向,氧化石墨烯的表面改性成为另一个研究重点.     

氧化石墨烯及其氧化铁复合物的原位合成

开发了在富氧Fe(acac),络合物体系中膨化氧化石墨制取氧化石墨烯/Fe2O3复合物的一步法.应用FT-IR、XRD、VSM、AFM及低温直流电导测量法对所制氧化石墨/Fe2O3复合物进行表征.FT-IR研究结果显示:膨化后,氧化石墨的环氧基团分解,同时形成了氧化铁粒子与氧化石墨烯复合物.AFM测试表明:在较高Fe2O3含量下,氧化石墨烯片层结构剥蚀形成厚达5 mm氧化石墨烯叠层.VSM研究显示:在室温和0.13 emu/g～5.5 emu/g范围内,全部复合物呈铁磁特性.这些复合物的导电性受控于准电子跃迁机制.     

石墨烯及其纳米复合材料的研究

石墨烯因其独特的结构和优异的性能,近年来已成为国内外研究的热点。简要介绍了石墨烯的制备方法,着重对石墨烯纳米复合材料的研究现状进行了综述。     

氧化还原法制备石墨烯及其在陶瓷材料中应用研究现状

氧化还原法制备石墨烯因原材料价格低廉、制备工艺简单,被认为是一种适应大规模制备石墨烯的途径,其中氧化石墨的还原是制备电学性能、力学性能与热稳定性优异的石墨烯的关键,而不同的还原方法对石墨烯的结构和性能影响较大。综述了氧化还原法制备石墨烯的还原方法,以及将石墨烯引入到陶瓷材料中所存在的问题和相应的解决方法。探讨了石墨烯对耐火材料在改善材料的强度和热震性的应用前景,并且指出了今后石墨烯在耐火材料中的应用需要重视的几个关键性问题。     

硫化铜/氧化石墨烯复合材料的制备与表征

首先采用Hummers法制备了氧化石墨烯(GO),反应体系为浓硫酸加硝酸钠,高锰酸钾为氧化剂,反应过程可分低温(4℃以下反应2h)、中温(38℃反应2h)和高温(98℃反应2h)3个阶段,将4g石墨经过强酸氧化得到氧化石墨烯(GO)。以制备的GO为结构单元,采用水热合成法将GO与硫化铜(CuS)进行复合,并以聚乙烯吡咯烷酮(PVP)为稳定剂来制备CuS/GO复合材料。制得的CuS/GO复合材料,为薄片结构单元叠加而成,形貌类似花瓣,大小均一,尺寸为5μm,具有较好的分散性,没有出现团聚现象。     

石墨烯的制备和改性及其与聚合物复合的研究进展

石墨烯是2004年问世的一种具有单层二维蜂窝状晶格结构的碳质新材料,也是性能优异的新型纳米复合材料填料.介绍了石墨烯的结构、制备方法;重点论述了石墨烯表面接枝以及聚合物基/石墨烯复合材料制备的研究进展,认为利用石墨烯的高强度、高导电率等优异性能可以赋予聚合物更加优异的特性.     

氧化石墨烯复合材料研究进展

氧化石墨烯(GO)是一种石墨烯衍生物,具有独特的二维纳米片层结构,表面含有大量羟基、环氧基、羧基和羰基等含氧官基团,加之具有超大的比表面积、良好的亲水性和生物相容性等特性,使其作为纳米组分更易与聚合物、无机物及小分子等物质作用制备复合材料。综述了近年来GO复合材料在吸附材料、分离材料、电极材料、传感器材料、界面改性、光电热材料、高性能材料及催化等领域的研究,并从可持续发展的角度对要拓宽和实现GO复合材料的大规模工业化应用存在的问题进行了总结及展望。     

聚合物基石墨烯纳米复合材料的研究进展

综述了聚合物基石墨烯及改性石墨烯纳米复合材料的研究进展.添加少量的石墨烯就可以显著提聚合物材料的各方面性能,因此,近年来石墨烯得到了学术界和工业界的高度关注,石墨烯、氧化石墨烯的改性,以及聚合物基石墨烯纳米复合材料被广泛研究.通过广泛的文献阅读对聚合物基石墨烯纳米复合材料的结构、制备方法以及性能进行了深入探讨.     

石墨烯/聚合物复合材料的研究进展

石墨烯是最近几年才发现的炭材料的新成员, 其完美的二维结构和许多奇特的性质, 引起了科学家的极大兴趣。石墨烯和氧化石墨烯的改性以及各种石墨烯/聚合物复合材料的制备成为当前研究的热点之一。与纯的聚合物相比, 石墨烯的加入可赋予复合材料不同的功能性, 不但表现出优异的力学和电学性能, 且具有优良的加工性能, 为复合材料提供了更广阔的应用空间。文中概述了石墨烯/聚合物复合材料的制备方法、结构及性能, 并展望了石墨烯及其聚合物复合材料的研究前景。     

Study on thermal properties of graphene foam/graphene sheets filled polymer composites

The polymer composites composed of graphene foam (GF), graphene sheets (GSs) and pliable polydimethylsiloxane (PDMS) were fabricated and their thermal properties were investigated. Due to the unique interconnected structure of GF, the thermal conductivity of GF/PDMS composite reaches 0.56 W m⁻¹ K⁻¹, which is about 300% that of pure PDMS, and 20% higher than that of GS/PDMS composite with the same graphene loading of 0.7 wt%. Its coefficient of thermal expansion is (80–137) × 10⁻⁶/K within 25–150 °C, much lower than those of GS/PDMS composite and pure PDMS. In addition, it also shows superior thermal and dimensional stability. All above results demonstrate that the GF/PDMS composite is a good candidate for thermal interface materials, which could be applied in the thermal management of electronic devices, etc.     

Carbon based conductive polymer composites

Composite material has attracted increasingly remarked interest over the last few decades and set it apart in its own class due to its distinct properties. World annual production is over 10 million tonnes and the market has in recent years been growing at 5–10% per annum. Among these materials, one subgroup, conductive polymer composite, has figured out and its importance is increasing in years to come. When used as conductive material, it possesses the merits of light weight, ease of manufacturing and chemical resistance. This review focuses on the electrical properties of carbon based conductive polymer composites. Special emphases are placed on the percolation phenomenon, the factors that affect the percolation threshold as well as related theoretical research work. Then mechanisms of electric conduction and factors influencing conductive properties are addressed.     

Interconnected graphene/polymer micro-tube piping composites for liquid sensing

Detection and analysis of volatile organic compounds （VOCs） as pollutants in the atmosphere and liquids are of great significance because of the detrimental effects of VOCs. A polymer-coated graphene micro-tube piping （GMP） structure with a cross-linked and interconnected channel network was synthesized for liquid sensing. By virtue of their unique cross-linked and interconnected channel network configuration, polycrystalline conformation, and the support of a polymer layer, the resistivity of the 3D hollow micro-tubing GMPs was sensitive to strain, ensuring high sensitivity of the liquid sensor （R/Ro of -4 × 10^3% for pure acetone and R/Ro of -105% for 0.01 wt.% acetone solution）. Due to the capillary force, the interfaces of the 3D structures can speed up the penetration of solvents into the polymer, thus promote distinct selectivity within seconds and significantly decrease the response time. Owing to their good selectivity, high sensitivity, rapid response and flexibility, and the ease of use of the sensors and the simplicity of the fabrication processes, the GMP/polymer composites should be a good candidate for liquid sensing.     

Enhanced thermal conductivity in polymer composites with aligned graphene nanosheets

We developed highly aligned graphene nanosheets (GNSs) in epoxy composites with incorporating magnetic GNS–Fe₃O₄ hybrids under a magnetic field with the aim to take full advantage of the high inplane thermal conductivity of graphene. GNS–Fe₃O₄ hybrids were fabricated by a simple coprecipitation method, and their morphology, chemistry, and structure were characterized. GNS–Fe₃O₄ hybrids were found to be homogenously dispersed and well aligned through the direction of the magnetic field in the epoxy matrix, as confirmed by SEM observation and Raman spectra analysis. The resulting epoxy/GNS–Fe₃O₄ composites possessed high thermal conductivity in a parallel magnetic-alignment direction at low GNS–Fe₃O₄ loadings, which greatly outperformed the composites with randomly dispersed bare GNSs. The obtained results indicated that the magnetic alignment of magnetic-functionalized GNSs is an effective way for greatly improving the thermal conductivity of the graphene-based composites.     

High thermal conductivity of flexible polymer composites due to synergistic effect of multilayer graphene flakes and graphene foam

Research on flexible thermal interface materials (TIMs) has shown that the interconnected network of graphene foam (GF) offers effective paths of heat transportation. In this work, a variant amount of multilayer graphene flakes (MGFs) was added into 0.2 vol% GF/polydimethylsiloxane (PDMS) composite. A remarkable synergistic effect between MGF and GF in improving thermal conductivity of polymer composites is achieved. With 2.7 vol% MGFs, the thermal conductivity of MGF/GF/PDMS composite reaches 1.08 W m⁻¹ K⁻¹, which is 80%, 184% and 440% higher than that of 2.7 vol% MGF/PDMS, GF/PDMS composites and pure PDMS, respectively. The MGF/GF/PDMS composite also shows superior thermal stability. The addition of MGFs and GF decreases slightly the elongation at break, but observably increases the Young’s modulus and tensile strength of composites compared with pure PDMS. The good performance of MGF/GF/PDMS composite makes it a good TIM for possible application in thermal management of electronics.     

Reduced graphene oxide deposited carbon fiber reinforced polymer composites for electromagnetic interference shielding

Reduced graphene oxide deposited carbon fiber (rGO-CF) was prepared by introducing GO onto CF surface through electrophoretic deposition method, following by reducing the GO sheets on CF with NaBH₄ solution. The rGO-CF was found to be more effective than CF to improve the electromagnetic interference (EMI) shielding property of unsaturated polyester (UP) based composites. With 0.75% mass fraction of rGO-CF, the shielding effectiveness of the composite reached 37.8 dB at the frequency range of 8.2–12.4 GHz (x-band), which had 16.3% increase than that of CF/UP composite (32.5 dB) in the same fiber mass fraction. The results suggest that rGO-CF is a good candidate for the use as a light-weight EMI shielding material.     

Vibration frequency of graphene based composites: A multiscale approach

This paper presents a multiscale approach for vibration frequency analysis of graphene/polymer composites. The graphene is modelled at the atomistic scale, and the matrix deformation is analysed by the continuum finite element method. Inter-connectivity between graphene and polymer matrix are assumed to be bonded by van der Waals interactions at the interface. The impact of geometrical configuration (armchair and zigzag), boundary conditions and length on the overall stiffness of the graphene reinforced plastics (GRP) is studied. The natural frequency and vibrational mode shapes of GRP studied have displayed dependence on the length and also the boundary conditions. The exceptional vibrational behaviour and large stiffness displayed by GRP makes them a potential replacement for conventional composite fibres such as carbon and glass fibres.     

基于化学气相沉积石墨烯/PEDOT-PSS共混复合材料的导电薄膜

采用液相剥离技术制备基于化学气相沉积（CVD）石墨烯/聚乙撑二氧噻吩-聚苯乙烯磺酸（PEDOT-PSS）共混复合材料的导电薄膜。采用原子力显微镜和SEM表征石墨烯/PEDOT-PSS复合薄膜的微观结构;通过紫外吸收谱、X射线光电子能谱、FTIR等分析技术探索该共混复合薄膜的导电机制。结果表明：石墨烯/PEDOT-PSS导电薄膜具有优异的电学特性,其方阻约为8 Ω/□;表面分析表明,石墨烯与PEDOT主链中五元噻吩发生π-π共轭效应,由此引起两作用体之间电子云密度的变化,该变化增加了PEDOT主链的载流子离域化程度,有利于PEDOT导电性的提升,同时提高石墨烯的载流子浓度,使CVD石墨烯/PEDOT-PSS复合薄膜的导电能力增强。