石墨烯/聚合物纳米复合材料研究进展

近年来,石墨烯以其完美的二维结构和众多优异的性能,引起了科学家的极大兴趣,成为纳米材料领域的一大研究热点。在众多研究中,基于石墨烯的聚合物纳米复合材料的研究是一个重要方向。本文在简要介绍石墨烯结构、性质和制备以及石墨烯的改性方法的基础上,重点总结了石墨烯基聚合物纳米复合材料的常用制备方法、结构及性能,进而得出大规模制备结构完整、尺寸和层数可控的高质量石墨烯及其衍生物是未来的研究热点,而改进石墨烯聚合物基复合材料合成方法,有效模拟石墨烯结构特征对复合材料的热、力、电、光等性能的影响则是该领域的重点发展方向。     

石墨烯/聚合物复合材料的研究进展

介绍了石墨烯的制备与改性方法,概述了石墨烯/聚合物复合材料的制备工艺,主要有熔融共混法、原位聚合法、溶液混合法及乳液混合法,并总结了石墨烯对聚合物导电性能、导热性能、耐热性能、物理机械性能和气体阻隔性能的影响.     

Chemically modified graphene oxide/polybenzimidazobenzophenanthroline nanocomposites with improved electrical conductivity

Graphene/polybenzimidazobenzophenanthroline nanocomposites were prepared through the liquid-phase exfoliation of graphene oxide (GO) and reduced graphene oxide (rGO) in methanesulfonic acid with subsequent solution mixing. Various chemical and combined chemical-thermal methods were examined to be effective for producing rGO with highly graphitic structure and excellent electrical conductivity. Raman and X-ray photoelectron spectroscopy showed higher degree of reduction of the GO with the combined chemical-thermal method compared to other chemical reduction processes. Structural characterization of the nanocomposites by X-ray diffraction, scanning electron microscopy and transmission electron microscopy showed good exfoliation and dispersion of both GO and rGO fillers in the polymer matrix. The thermogravimetric analysis found that the nanocomposites with rGO have higher onset and maximum weight loss temperatures than those with GO. Compared with the pure polymer, the electrical conductivity of the nanocomposites containing 10 wt% GO and GO reduced by the combined chemical-thermal treatment showed a remarkable increase by four and seven orders of magnitude, respectively. Long-term in-situ thermal reduction was performed to further improve the conductivities of the nanocomposites.     

PS/POE/功能化石墨烯纳米复合材料的制备和性能研究

利用马来酸酐接枝聚烯烃(POE-g-MAH)弹性体为增韧剂,乙二胺功能化石墨烯(G-EDA)为纳米填料,经熔融共混法制备了聚苯乙烯(PS)/POE-g-MAH/G-EDA纳米复合材料,并对填料和所得纳米复合材料的结构和性能进行了全面的表征。红外光谱(FTIR)、扫描电子显微镜(SEM)、力学性能、维卡软化温度和熔融指数测试表明:乙二胺(EDA)已成功接枝于石墨烯的表面上;共混过程中,POE-g-MAH的酐基与EDA的氨基发生反应改善了共混体系的界面相容性;G-EDA在熔融共混过程中均匀分散于PS基体中;随着G-EDA含量的增加,复合材料的拉伸强度先增大后降低,当G-EDA质量分数为0.5%时,复合材料的拉伸强度达到最大值,比PS/POE-g-MAH提高了12.3%,比纯PS提高了15.5%;而当G-EDA质量分数为0.75%时,复合材料的冲击强度达到最大值,比PS/POE-g-MAH提高了22%,比纯PS提高了22.4%。因此,当G-EDA的质量分数在0.5%~0.75%之间时,复合材料的综合力学性能最好。G-EDA的加入,纳米复合材料的邵氏A硬度、维卡软化温度等都逐渐增大,而熔融指数逐渐降低。     

Improved properties of highly oriented graphene/polymer nanocomposites

A kind of molecular‐level dispersed and highly oriented graphene monolayer nanocomposite film was successfully obtained by in situ reduction of phenyl isocyanate functionalized graphite oxide (RPIGO) in N,N‐dimethylformamide in the presence of polystyrene (PS). Atomic force microscopy and transmission electron microscopy results show that the RPIGO monolayers were not only homogeneously intercalated into the PS matrix but also arranged parallel to the surface of the nanocomposite films. Because of the efficient interaction between the graphene monolayers and PS matrix, the mechanical properties of the graphene‐based nanocomposite films improved significantly. Compared with the pure PS film, a 28.4% increase in the Young's modulus and a 27.8% improvement in the tensile strength of the RPIGO–PS nanocomposites films were obtained with the addition of only 0.5 wt % graphite oxide. The glass‐transition temperature and onset degradation temperature of PS also increased from 96.6 and 427°C to 103.2 and 439°C, respectively. The improvement of the properties was mainly due to the large lateral thickness ratio and the high orientation of graphene monolayers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Kevlar oligomer functionalized graphene for polymer composites

Kevlar oligomer functionalized graphene (FGS) was prepared by simple grafting of amino-terminated Kevlar oligomer on graphene oxide (GO) followed by reducing with hydrazine hydrate. The incorporation of FGS shows pronounced effect on the host polymers. High-level reinforcement of both PMMA and PI is observed with low content of FGS (≤0.2 wt %), in this lower loading range, the tensile modulus and strength of composites increase almost linearly as a function of the adding amount of FGS. But no further improvement is obtained as the content of FGS further increased (>0.2 wt %). The mechanism under the reinforcement effect against the FGS loadings is discussed based on the morphological characterizations of the composites. The thermal properties of the composites were also investigated. The glass transition temperature and thermal stability of PMMA were dramatically increased even with the addition of only a small amount of FGS.     

One-pot in situ ball milling preparation of polymer/graphene nanocomposites

A one-pot method which involves peeling graphite nanosheets (GNs) off into graphenes in polymer solution and in situ forming polymer/graphene sheets nanocomposites by using ball milling is presented. Via this approach, nanocomposites based on maleic anhydride grafted poly (ethylene-co-vinyl acetate) (EVA-g-MAH) and graphene sheets comprising one to five layers were accomplished. The resulted EVA-g-MAH/graphene nanocomposites displayed a percolation threshold around 5.0 wt %, much lower than that of the EVA-g-MAH/GNs nanocomposites prepared by direct solution blending (∼ 13.0 wt %). The nanocomposite containing 10 wt % of graphene sheets exhibited a higher maximum decomposition temperature by ∼ 10°C when compared with the virgin polymer and the corresponding nanocomposite loaded with 10 wt % of GNs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Functionalized graphenes with polymer toughener as novel interface modifier for property-tailored polylactic acid/graphene nanocomposites

In this work, an effective strategy for engineering the interfacial compatibility between graphene and polylactic acid (PLA) was developed by manipulating the functionalization of graphene and introducing an epoxy-containing elastomer modifier. Curing between the functional groups of the modified graphene and the epoxy groups of the elastomer modifier resulted in controlled dispersion and distribution of graphene in the composite system and hence improved the interfacial adhesion between PLA and graphene. Effects of different graphene functionalization with polymer toughener on morphology, viscoelasticity, and thermal properties of the resulting PLA nanocomposites were thoroughly examined. The resulting percolated structures were the origin of the improved properties of PLA/graphene nanocomposites. The mechanism on property tailoring from interface engineering through dual modifiers are also proposed. Overall, the insight into the interface engineering between the functionalized graphene and the matrix through an elastomer modifier offers a novel way for the future design of graphene polymer nanocomposites.     

石墨烯/聚合物纳米复合材料制备与微波吸收性能研究进展

二维片状的石墨烯不仅具有优异的力学、热学和电学性能,而且还具有较好的微波吸收特性。自它被发现以来,一直受到科学界的广泛关注,目前已有学者将其与聚合物复合,制备了石墨烯/聚合物纳米复合材料,这种新型微波吸收材料不仅吸波效果好而且密度小、易加工。目前石墨烯/聚合物纳米复合材料用于微波吸收的报道还比较少,该研究基本处于起步阶段。本文首先概述了石墨烯独特的物理结构和优异的力学、热学、电学性能,然后综述了石墨烯/聚合物纳米复合材料的制备方法,并分析了其微波吸收机理,最后结合国内外研究现状展望了石墨烯/聚合物纳米复合材料制备与微波吸收性能研究的发展方向,指出调控复合材料的微观形貌,对石墨烯进行磁性掺杂,探索石墨烯与聚合物微波吸收的协同效应将成为今后研究的重点和热点。     

Electrospinning of polymer nanofibers loaded with noncovalently functionalized graphene

Pristine graphene/polyvinyl alcohol (PVA) nanofibers were prepared by electrospinning an aqueous solution of polyvinylpyrrolidone‐stabilized graphene and PVA. This is the first report of electrospun nanofibers reinforced with dispersed pristine graphene. We examine the relationship between graphene loading and critical electrospinning parameters. Microscopy indicates uniform fiber formation and excellent graphene dispersion within the fiber. Rheological data indicates that the excellent level of graphene dispersion enhances the modulus of the polymer by 205%. We also find that the graphene significantly increases the fibers' thermal stability (increase of 15°C) and crystallinity (59% increase) above the baseline. In fact, the graphene may act as nucleating points for increased crystallinity. These graphene/polymer nanofibers have the potential to serve in a variety of applications, including electrodes, conductive wires, and biomedical materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Characterization and performance of dodecyl amine functionalized graphene oxide and dodecyl amine functionalized graphene/high‐density polyethylene nanocomposites: A comparative study

Dodecyl amine (DA) functionalized graphene oxide(DA‐GO) and dodecyl amine functionalized reduced graphene oxide (DA‐RGO) were produced by using amidation reaction and chemical reduction, then two kinds of well dispersed DA‐GO/high‐density polyethylene (HDPE) and DA‐RGO/HDPE nanocomposites were prepared by solution mixing method and hot‐pressing process. Thermogravimetric, X‐ray photoelectron spectroscopy, Fourier transforms infrared spectroscopy, X‐ray diffractions, and Raman spectroscopy analyses showed that DA was successfully grafted onto the graphene oxide surface by uncleophilic substitution and the amidation reaction, which increased the intragallery spacing of graphite oxide, resulting in the uniform dispersion of DA‐GO and DA‐RGO in the nonpolar xylene solvent. Morphological analysis of nanocomposites showed that both DA‐GO and DA‐RGO were homogeneously dispersed in HDPE matrix and formed strong interfacial interaction. Although the crystallinity, dynamic mechanical, gas barrier, and thermal stability properties of HDPE were significantly improved by addition of small amount of DA‐GO or DA‐RGO, the performance comparison of DA‐GO/HDPE and DA‐RGO/HDPE nanocomposites indicated that the reduction of DA‐GO was not necessary because the interfacial adhesion and aspect ratio of graphene sheets had hardly changed after reduction, which resulting in almost the same properties between DA‐GO/HDPE and DA‐RGO/HDPE nanocomposites. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39803.     

Multiscale model to investigate the effect of graphene on the fracture characteristics of graphene/polymer nanocomposites

In this theoretical research work, the fracture characteristics of graphene-modified polymer nanocomposites were studied. A three-dimensional representative volume element-based multiscale model was developed in a finite element environment. Graphene sheets were modeled in an atomistic state, whereas the polymer matrix was modeled as a continuum. Van der Waals interactions between the matrix and graphene sheets were simulated employing truss elements. Fracture characteristics of graphene/polymer nanocomposites were investigated in conjunction with the virtual crack closure technique. The results demonstrate that fracture characteristics in terms of the strain energy release rate were affected for a crack lying in a polymer reinforced with graphene. A shielding effect from the crack driving forces is considered to be the reason for enhanced fracture resistance in graphene-modified polymer nanocomposites.     

Thermal behavior of thermoplastic polymer nanocomposites containing graphene nanoplatelets

Polypropylene (PP), acrylonitrile butadiene styrene (ABS), and thermoplastic polyurethane (TPU) nanocomposites filled with 5 wt % of two different kinds of commercially available graphene nanoplatelets (GNPs) were prepared. Composites materials were characterized in terms of thermal properties (thermal conductivity and thermal stability) in order to study the effect of different fillers within different thermoplastic matrices. The exfoliation process and the mechanical properties were also investigated. We chose three different thermoplastic polymers (polyolefin, copolymer and elastomer) to cover a wide range of thermoplastic materials and identify a guideline in the use of GNPs for nanocomposite materials. No drastic differences were observed in terms of mechanical properties when the same matrices were filled with different GNPs. Concerning thermal conductivity, it was observed that the GNPs plane dimensions play a crucial role in the increase of conductive properties. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44814.     

聚合物功能化石墨烯的合成及应用研究进展(一)

着重评述了采用共价连接和非共价连接技术制备聚合物功能化石墨烯的方法,介绍了聚合物功能化石墨烯的应用概况。     

A review on synthesis and properties of polymer functionalized graphene

This review highlights the functionalization chemistry of graphene with polymers by both covalent and non-covalent approaches. Due to the strong cohesive interactions graphene platelets agglomerate, causing difficulty to attain its optimum properties. The covalent functionalization is illuminated both from ‘grafting to’ and ‘grafting from’ techniques discussing the merits and demerits of the processes. The controlled free radical polymerization techniques used for this purpose e.g. ATRP, SET–LRP and RAFT etc. are discussed along with the conventional free radical polymerization. We have also noted the various approaches used in non-covalent functionalization e.g. π–π, H-bonding and hydrophobic interactions. These functionalized graphenes show good and stable dispersion facilitating composite formation with commodity plastics enhancing it's mechanical, thermal and conductivity properties. The optoelectronic properties of these functionalized graphene are interesting to fabricate sensors, photovoltaics, supercapacitors etc. A short account of the properties of these modified graphenes is also embodied with an emphasis on different area where future developments are expected.     

聚合物功能化石墨烯的合成及应用研究进展(二)

着重评述了采用共价连接和非共价连接技术制备聚合物功能化石墨烯的方法,介绍了聚合物功能化石墨烯的应用概况。     

Sonochemical synthesis and characterization of amine‐modified graphene/conducting polymer nanocomposites

The objective of this work is to modify graphene and study the effect of modification of graphene in thermal and electrical properties of graphene/polypyrrole and graphene/polyaniline nanocomposites. The amine functionalization of graphene was confirmed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. The nanocomposites were prepared by insitu oxidative polymerization method using ammonium persulfate as oxidant. Field emission scanning electron microscopy and high‐resolution transmission electron microscopy were used to study the morphology of the nanocomposites which indicates toward the better dispersion of modified graphene within the polymer matrices as compared to unmodified composites. The modification of graphene played an important role in the noticeable improvements in electrical conductivity of the prepared composites. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

High-yield water-phase exfoliated few-defect graphene for high performance polymer nanocomposites

Application of graphene requires a high-yield, low-cost, scalable production method, but it remains highly challenging. We here report a water-phase technique to produce few-defect graphene nanosheets (FGS) with a high exfoliation yield (92%), based on the chemically expanded graphite with ultrahigh specific surface areas, and demonstrate the application in graphene-polymer nanocomposites. The exfoliated FGS has low degree of oxidation and preserves good mechanical and electrical properties, revealing promising potential for improving comprehensive properties of polymer composites. When 0.5 wt% FGS was incorporated to poly(methyl methacrylate) (PMMA), the 5% weight loss temperature and storage modulus increase by 87°C and 21%, respectively, relative to the neat polymer. With increasing the content of FGS to 4.6 wt%, the glass transition temperature of the composite increases by 25°C. In addition, the composites show a percolation threshold as low as 0.25 vol% and excellent electrical conductivity (50 S/m for 2.7 vol% FGS-PMMA composite).     

Investigation of the crystalline structure of PVDF in PVDF/PMMA/graphene polymer blend nanocomposites

In this work, we report the preparation of poly(vinylidene fluoride)/poly methylmethacrylate (PVDF/PMMA)/graphene polymer blend nanocomposites via synthesis of PMMA/graphene as a masterbatch through in situ polymerization. The PMMA/graphene masterbatch compounded with PVDF by solution mixing in different ratios. The compounding was followed by solution casting to form polymer blend nanocomposites. Solution cast films were subjected to thermal treatments at three different temperatures. The crystalline structure of thermally treated samples was studied with X‐ray diffraction spectroscopy and Differential Scanning Calorimetric (DSC) analysis. Results indicated PMMA chains persuade the β crystalline form in PVDF but cannot stabilize them in elevated temperature; however, graphene sheets due to restricting effect on TT conformation chains are able to stabilize them. DSC data revealed the graphene sheets can increase the crystallinity of PVDF and also act as nucleating agents. Transmission Electron Microscopy demonstrated coexistence of the different stacking orders of graphene sheets in both masterbatch and polymer blend nanocomposite. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Carbon nanotubes‐polymer nanocomposites for controlled heating materials

Nanocomposites of modified carbon nanotubes (CNT) and either polyurethane (PU), poly(vinyl acetate) (PVAc), or silicone materials were synthetized and characterized for thermal mat application. The obtained results revealed that the polymer used as a matrix had an impact on the electrical resistance of the mats. The lowest results of 32 Ω of resistance was registered with silicone‐based mats containing 5 wt % of CNT. For the same CNT content the mats based on PVAc and PU displayed values of 55 and 60 Ω, respectively. The low resistance properties of silicone‐based materials were due principally to the good compatibility of both polymer and functionalized CNT. Because of the low resistance values, this mat was subjected to thermovision analysis revealing that the samples reached temperature of about 60 °C in 9 min and 70 °C after 27 min of 27 V of applied potential. The results showed an almost uniform temperature distribution in the samples’ surface with some high and low temperature spots, which were attributed to nonuniform distribution of CNT in the polymer matrix. In summary, all the obtained results confirm that silicone‐CNT are very promising materials that can be used as low‐voltage heating mats. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44194.