聚吡咯/镀银纳米石墨微片复合材料的制备与表征

以氧化石墨为原料,制备膨胀石墨,在超声波的作用下,膨胀石墨的片层结构发生剥离得到纳米石墨微片,对纳米石墨微片进行化学镀银,制备镀银纳米石墨微片,然后采用原位聚合法制备了聚吡咯/镀银纳米石墨微片复合材料。结果表明,纳米石墨微片的厚度为30～90nm,直径为1～20μm,具有相当大的径厚比(平均为200),该结构对纳米石墨微片在聚合物基体中形成导电网络极为有利;镀银纳米石墨微片的厚度为200～250nm,被聚吡咯完全包覆,并以纳米级尺寸均匀分散在聚吡咯基体中;聚吡咯/镀银纳米石墨微片复合材料的耐热性能和导电性能较纯聚吡咯均有所提高。     

新型导电填料——纳米石墨微片

经过超声波粉碎,可将膨胀石墨制备成一种新型导电填料——纳米石墨微片。它的厚度为纳米,直径在微米范围,具有很大的形状比。将纳米石墨微片分散于聚乙烯、聚苯乙烯、聚甲基丙烯酸甲酯、尼龙等聚合物基体中制备导电复合材料,其渗滤阀值远低于一般的导电填料复合体系。纳米石墨微片有望在导电材料、电磁屏蔽材料、电加热材料等领域得到应用。     

聚合物/氧化石墨纳米复合材料的研究进展

氧化石墨因具有层状结构,能够以插层复合的方式与聚合物形成聚合物纳米复合材料。本文介绍了氧化石墨的结构、性能特点以及聚合物/氧化石墨纳米复合材料的研究进展情况,包括聚合物/氧化石墨纳米复合材料的制备方法、种类、结构与性能特点、应用前景与研究展望。     

聚合物-纳米无机粒子复合微球研究新进展

近年来,聚合物-纳米无机粒子复合微球相关的设计、制备、以及应用研究得到了科学界众多学者的广泛关注与探索。本文论述了单体聚合法制备聚合物-纳米无机粒子复合微球的研究近况,主要介绍了悬浮聚合、乳液聚合(微乳液聚合、Pickering乳液聚合、细乳液聚合、反相乳液聚合、无皂乳液聚合)、分散聚合及溶液聚合的制备方法。概述了聚合物-纳米无机粒子复合微球在生物医药、光电材料、保护涂层、催化等方面的应用,展望了聚合物-纳米无机粒子复合微球的发展趋势。     

导电聚合物/石墨烯复合材料在防腐涂料中的研究进展

综述了聚苯胺和聚吡咯基导电聚合物与石墨烯、氧化石墨烯(GO)和还原氧化石墨烯(rRO)所形成的复合防腐材料的制备工艺及其在金属防腐涂料领域的应用,并分析总结了现有复合防腐材料的防腐机理,同时对未来导电聚合物/石墨烯复合防腐材料的发展进行了展望。具有良好环境稳定性的聚噻吩基石墨烯复合防腐材料将是今后研究的主题。     

聚吡咯/无机粒子纳米复合材料的研究进展

综述了聚吡咯（PPy）与无机磁性粒子、金属氧化物、碳系无机物（炭黑、碳纳米管、纳米石墨微片）等无机粒子组成的功能性纳米复合材料的制备方法及其力学、光学、电学、磁学等性能,并介绍了近年来各类纳米PPy/无机粒子功能性复合材料在电磁屏蔽、隐身材料、抗静电材料、导电高分子电容器、二次电池以及传感器等领域的研究现状及发展趋势。     

聚合物/氧化石墨纳米复合材料的研究进展

氧化石墨(GO)因其独特的结构及特性引起了人们的关注,它与聚合物通过插层复合技术形成的聚合物/氧化石墨纳米复合材料是一种很有发展前景的新型材料.本文对氧化石墨的结构、聚合物/氧化石墨纳米复合材料的制备及其性能进行了综述,并对其未来发展方向进行了展望.     

导电胶用纳米石墨微片的表面化学镀Cu及其表征

采用无钯化学镀Cu法对纳米石墨微片表面进行处理,并对其制备工艺进行了探究,旨在得到一种导电胶用新型导电填料。研究结果表明:当改性剂浓度为3 g/L、AgNO3浓度为3 g/L、氨水浓度为40 g/L、m(无水乙醇)∶m(水)=9∶1、活化温度为50℃和活化时间为1.5 h时,纳米石墨微片表面镀上了一层致密而均匀的金属Cu层,Cu层的厚度约为100 nm,Cu沉积量超过60%(相对于纳米石墨微片质量而言)。     

聚合物/石墨导电纳米复合材料制备方法进展

综述了聚合物/石墨导电纳米复合材料制备方法的进展。首次将制备方法归为碱金属插层聚合法、膨胀石墨原位聚合法和膨胀石墨共混复合法3大类,详细介绍了它们的概念、特点和研究概况。特别是重点介绍了超声粉化法、表面处理法、助剂预复合法、预包覆母料法以及其他方法等膨胀石墨间接共混复合法的概念和概况。还对聚合物/石墨导电纳米复合材料领域的未来研究重点提出了自己的看法。     

超高分子量聚乙烯/石墨包覆纳米铜复合导电材料研究

在NaBH4/EDA体系中还原CuCl2石墨层间化合物合成了石墨包覆纳米铜复合填料(GECNP).以GECNP为导电填料,采用球磨共混-热压成型工艺制备了超高分子量聚乙烯(UHMWPE)基复合材料.UHMWPE/GECNP复合材料的X射线衍射(XRD)分析表明:在制备过程中无新相生成;扫描电镜(SEM)观察发现:其微观结构均匀,GECNP以纳米片状分散于基体中,构成导电网络;有关导电性的研究表明:复合材料导电机制符合聚合物基复合材料的导电渗滤理论,渗滤阈值为8.766%,低于常规碳系填料.当GECNP体积浓度为12.8%时,体系电导率最高,为7.55S/cm,高于石墨纳米片填料.     

Effect of dispersion on graphite nanosheet composites

By intercalating and exfoliating natural graphite flakes, expanded graphite was obtained and used as the additive for making composites. The expanded graphite was composed of partly connected graphite nanosheets. Three types of composites were made, representing three levels of dispersing the graphite nanosheets. The first was the impregnation of epoxy resin to the expanded graphite by resin transfer molding. No dispersion was applied, and the expanded graphite can retain its original shape. The second was the use of a high‐power sonication to break apart the expanded graphite. The thickness of the sonicated expanded graphite was reduced to about 100 times. The third method was to use a high‐shear strain rate to separate the graphite nanosheets from the expanded graphite and to disperse them into the resin. The thickness range of the graphite nanosheets was 20–50 nm, about 100 times thinner than the sonicated ones. Compression and impact tests were conducted. The influence of dispersion on the material behavior was studied. Some fracture modes associated with the layered microstructures of the graphite nanosheets were observed. A simple model was used to study the stress transfer and frictional energy consumption of the pullout of the nanosheet. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers     

Regenerated cellulose nanocomposites reinforced with exfoliated graphite nanosheets using BMIMCL ionic liquid

Green nanocomposites of regenerated cellulose/exfoliated graphite nanosheets films with low nanofiller loadings were prepared using environmentally benign 1-butyl-3-methylimidazolium chloride (BMIMCl) ionic liquid. X-ray diffraction revealed well developed intercalated nanocomposites. The tensile strength and Young's modulus of the prepared nanocomposites were increased by 97.5% and 172% respectively when 0.75 wt.% and 1 wt.% exfoliated graphite nanosheets were added. The results were validated using the Halpin–Tsai model. The exfoliated graphite nanosheets were unidirectionally aligned in the regenerated cellulose parallel to the surface of the nanocomposites as revealed by transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Also, the TEM and FESEM revealed uniform dispersion of the exfoliated graphite nanosheets and good interaction between the nanofillers and the matrix. The addition of the exfoliated graphite nanosheets enhanced the thermal stability and reduced the water absorption and diffusivity of the nanocomposites.     

Preparation of graphite nanosheets in different solvents by sand milling and their enhancement on tribological properties of lithiumbased grease

Graphite nanosheets with the average thicknesses ranging from 24.4 to 48.9 nm were prepared with the use of expanded graphite as the raw material by sand milling in deionized water, anhydrous ethanol, glycerol, and 1,4-butanediol, respectively. Anhydrous ethanol favored the formation of graphite nanosheets with a smaller average thickness. When the graphite nanosheets with the content of 2 wt% were added in lithium-based grease, the average friction coefficient decreased by 27% as compared with the pure lithium-based grease. The weld point and load wear index were 1.6 and 1.4 times those of the pure lithium-based grease, respectively. The tribological properties of the graphite nanosheet-containing lithium-based grease were comparable with those of the graphene-containing lithium-based grease.     

Preparation and characterization of a PMMA/Ce(OH)3, Pr2O3/graphite nanosheet composite

An easy process for the synthesis of poly(methyl methacrylate)/Ce(OH)₃, Pr₂O₃/graphite nanosheet (PMMA/Ce(OH)₃, Pr₂O₃/NanoG) composite was developed. Graphite nanosheets (NanoG) were prepared by treating the expanded graphite with sonication in aqueous alcohol solution. The PMMA/Ce(OH)₃, Pr₂O₃/NanoG composites were prepared via in situ polymerization of MMA monomer in the presence of graphite nanosheets and Ce(OH)₃, Pr₂O₃ through reverse micelle template, in which the methyl methacrylate was designated as the oily phase. The composites were then dispersed with chloroform and coated on glass slides to form films. Scanning and transmission electron microscopy were used to characterize the structure and dispersion of the graphite nanosheets and the composites. The results showed that the high-aspect-ratio structure of the nanosheets played an important role in forming a conducting network in the PMMA matrix. From thermogravimetric analysis, the introduction of graphite nanosheets and inorganic nanopartices exhibited a beneficial effect on the thermal stability of PMMA.     

RESS制备石墨烯纳米片及防止其再团聚的新方法

本文以天然鳞片石墨为原料,利用超临界状态下二氧化碳的快速膨胀（RESS）来剥离石墨产生石墨烯纳米片。电子显微镜（SEM）表征证实RESS可有效地实现石墨的剥离,并产生了一些石墨烯纳米片层。同时,为了解决再团聚难题,提出利用碳纳米管在产生石墨烯纳米片间穿层的方法和利用小分子包覆法来防止其再团聚,实验证实都起到良好的效果。     

Preparation and characterization of graphite nanosheets from ultrasonic powdering technique

Natural flake graphite was exfoliated into exfoliated graphite via an acid intercalation procedure. The resulting exfoliated graphite was a worm-like particle composed of graphite sheets with thickness in the nanometer scale. Subjecting it to ultrasonic irradiation, the exfoliated graphite was effectively further foliated into isolated graphite nanosheets. SEM, TEM, SAD, laser counting, and BET measurements revealed that the graphite nanosheets prepared with 10 h irradiation were about 52 nm in thickness and 13 μm in diameter. FTIR examination showed that there were oxygen-containing groups presented on the surface of the exfoliated graphite. This result substantiated the statement reported in the literature that acid treatment could result in oxidization of carbon bonds on graphite surface.     

Synthesis and properties of poly(4,4′-oxybis(benzene)disulfide)/graphite nanocomposites via in situ ring-opening polymerization of macrocyclic oligomers

An effective method for the preparation of poly(4,4′-oxybis(benzene)disulfide)/graphite nanosheet composites via in situ ring-opening polymerization of macrocyclic oligomers were reported. Completely exfoliated graphite nanosheets were prepared under the microwave irradiation followed by sonication in solution. The nanocomposites were fabricated via in situ melt ring-opening polymerization of macrocyclic oligomers in the presence of graphite nanosheets. The graphite nanosheets and resulted poly(arylene disulfide)/graphite nanocomposites were characterized with field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), tensile tester and electrical conductivity measurements. Compared with pure polymer, the electrical conductivity of the poly(arylene disulfide)/graphite nanocomposites were dramatically increased and had a value of about 10⁻³ S/cm for the nanocomposite containing 5 wt% graphite. The nanocomposites exhibit as both high performance polymeric material and electrically conductive material. Therefore, they show potential applications as high temperature conducting materials.     

Influence of graphite nanosheets on the structure and properties of PVC‐based nanocomposites

Polyvinyl chloride‐ (PVC)‐ based nanocomposites, containing graphite nanosheets (G), which may be used as electromagnetic wave absorbers was developed and investigated. The microstructure of polyvinyl chloride/graphite nanocomposites (PVC/G) were examined by means of X ‐ray diffraction, scanning electron microscopy (SEM), and thermal gravimetric analyses (TGA). SEM image reveals that the graphite nanosheets were well dispersed in the PVC matrix without agglomeration. Thermal stability of the PVC/G nanocomposites is improved as a result of inclusion of graphite nanosheets. The PVC/G nanocomposites were characterized to investigate the effect of dispersion of graphite nanosheets in PVC matrix. The dielectric spectroscopy of PVC/G nanocomposites in frequency range from 1 to 12 GHz has been performed. The results show that PVC/G nanocomposites exhibit high dielectric constant at the measured frequencies. Coefficient of attenuation and coefficient of reflection of PVC/G composites have been also examined in a frequency range from 1 to 12 GHz. The electromagnetic interference shielding effectiveness (EMI) depends on graphite volume fraction in the composite. The results show that the PVC/G represents a new class of conducting lightweight nanomaterial that can absorb electromagnetic waves at microwave frequency and may be promising for future commercial use. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of graphene nanosheet/polymer composites using in situ reduction-extractive dispersion

Graphene nanosheet/polymer composites were prepared using in situ reduction-extractive dispersion technology. The morphology and microstructure of the composites were examined by scanning electron and optical microscopy. The results indicate that graphene nanosheets from the reduction of graphite oxide are about 5 nm thick and 1-3 μm in diameter. Reduction-extractive dispersion technology can effectively promote the dispersion of graphene nanosheets and consequently an excellent conductive network is formed in the matrix. The percolation threshold of the composite is about 0.15 vol.%. When the graphene nanosheet content is lower than 1.5 vol.%, the conductivity of the composites is 3-5 orders of magnitude higher than that of composites filled with graphite nanosheets from expanded graphite.     

Study on the graphite nanosheets/resin shielding coatings

Shielding coatings based on graphite nanosheets were prepared by compounding method. The surface morphology of the graphite nanosheets and conductive coatings was examined by scanning electron microscopy. The surface resistivity of the coatings was greatly declined by incorporating the graphite nanosheets. The electromagnetic interference shielding effectiveness (SE) from 0.3 MHz to 1.5 GHz was also studied, and found that the SE of the coatings was consistent with its conductivity. The best sample was shown to exhibit up to 38 dB of SE at 1.5 GHz (with a thickness of 400 μm). The main shielding mechanism of the system was reflection and multiple reflections.