羟基磷灰石/壳聚糖/氧化石墨烯三相复合膜合成与研究前景

目前,基于羟基磷灰石的二相复合膜在骨修复生物材料的研究中已经取得了很大进展,其中羟基磷灰石/壳聚糖复合膜被广泛合成和应用,但仍存在力学性能不足的问题,因而限制了其在临床上的大量应用。氧化石墨烯作为新兴的材料,具备独特的层状结构并有着良好的力学性能。为了提高复合膜的强度,我们利用氧化石墨烯对羟基磷灰石/壳聚糖复合膜进行改性以进一步改善羟基磷灰石/壳聚糖复合膜的力学性能。本综述概括了羟基磷灰石/壳聚糖/氧化石墨烯复合膜的研究现状,对其特点、制备、性能进行了探究,并对基于羟基磷灰石的多相复合材料研究前景予以展望。     

煤基石墨烯材料制备研究进展

石墨烯材料由于其超强的力学性能,极高的电导率,超大的比表面积及良好的化学稳定性,在光、电、磁等方面的应用具有极大的潜力。煤炭资源含有大量可石墨化的芳香烃类,是制备石墨烯的天然材料。综述了采用不同技术制备氧化石墨烯、石墨烯和石墨烯量子点研究进展,总结了煤基石墨烯材料常用制备方法(化学气相沉积法和化学氧化法)的优缺点,最后对煤基石墨烯材料制备未来发展进行了展望。     

氧化石墨烯在阻燃聚合物中的应用研究进展

石墨烯作为一种重要的碳材料,具有非常好的热稳定性能、力学性能,可以将其作为阻燃剂运用到聚合物材料中,从而提高复合材料的阻燃性能。而氧化石墨烯作为石墨烯的一种衍生物,在经过功能化后不仅弥补了其在高分子材料中难于分散的缺点,并且还可以通过表面改性引入其他元素赋予石墨烯新的性能。本文综述了氧化石墨烯及其修饰后的功能化石墨烯在阻燃聚合物中的应用研究进展。     

石墨烯、3D石墨烯及其复合材料的研究进展

石墨烯是由单层碳原子紧密堆叠而成的蜂窝状材料,具有比表面积大、传热性能好、导电能力强等优点,普遍应用于各个领域。但由于石墨烯使用过程中易团聚,导致其应用领域受限。石墨烯组装而成的3D石墨烯拥有更大的活性表面积等特性,近年来引发密切关注。与此同时,石墨烯、3D石墨烯改性成为当前探究的焦点。本文在介绍石墨烯、3D石墨烯的结构、性能及石墨烯制备的基础上,总结了3种复合材料的主要制备途径,并且分析了其合成方法的利弊。重点探讨了它们在锂离子电池、燃料电池的电化学催化剂及传感器中的应用,简述了复合材料优良性能产生的机理。提出在掺杂改性中应注意各元素掺杂量、掺杂比例、掺杂位点的确定等问题。最后指出了石墨烯、3D石墨烯及其复合材料的制备还面临不稳定、无法大规模生产、导电率低的瓶颈并对其在固态金属锂电池、透明电池、吸附材料等领域的发展前景做了展望。     

石墨质改性混凝土高温性能的研究

通过热处理后混凝土力学性能及微观结构的变化,研究了石墨、氧化石墨烯复合玄武岩纤维对混凝土高温性能的影响。结果表明:石墨的添加会引起混凝土力学稳定性的降低,而氧化石墨烯则可以大幅度提升混凝土的高温力学稳定性,有效降低了热处理所带来的劣化影响;玄武岩纤维与石墨、氧化石墨烯的复合使用均未形成协同作用效果,反而降低了试样的力学性能。微观分析显示石墨分散在材料体系之中形成了界面缺陷,而氧化石墨烯可以在材料系统中形成紧密连续的交联结构,有效提高了混凝土的高温力学性能。     

文摘

聚合物基石墨烯纳米复合材料的研究进展【刊,中】,张建,,化工新型材料．2012,40（8）：8—10 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高聚合物材料各方面性能。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。     

氧化石墨烯/聚氨酯复合材料的制备及性能研究

采用溶液共混浇注成膜法制备氧化石墨烯/热塑性聚氨酯(TPU)复合材料,并对其结构和性能进行研究。结果表明:氧化石墨烯在TPU基体材料中分散较好;随着氧化石墨烯用量(0～5份)的增大,氧化石墨烯/TPU复合材料的拉伸强度增大,拉断伸长率未明显下降;当相同用量(均为1份)的氧化石墨烯、碳纳米管、石墨和炭黑分别填充TPU时,氧化石墨烯/TPU复合材料物理性能提高幅度最大,补强性能最好。     

石墨烯在复合防腐涂层中的应用研究进展

基于石墨烯和氧化石墨烯不同的改性方法综述了石墨烯在防腐复合涂层中应用的研究进展,探讨了石墨烯防腐蚀机理,论述了石墨烯和氧化石墨稀复合防腐涂层的合成方法。其中石墨烯的改性方法有：原位改性石墨烯、电化学沉积方法和原位还原氧化石墨烯,而氧化石墨稀的改性方法包括有机改性剂改性氧化石墨烯、无机改性剂改性氧化石墨烯和微胶囊技术改性氧化石墨;并对石墨烯复合防腐涂层的发展前景进行了展望。     

石墨烯气凝胶复合材料制备及吸附性能的研究进展

石墨烯气凝胶(GA)拥有以石墨烯为主体的多孔互联三维海绵状网络结构。作为一种新兴的纳米多孔材料,因其具有高疏水性、高比表面积、高孔隙率以及良好的化学稳定性,在吸附领域具有巨大的应用前景。结合相关研究,重点介绍了石墨烯、纤维素/石墨烯、碳纳米管/石墨烯、氮掺杂/石墨烯、金属氧化物/石墨烯等几种体系的气凝胶材料的制备方法,并对其吸附性能的研究进展进行了阐述。     

热塑性聚氨酯/石墨烯改性聚氨酯注浆材料的制备与性能研究

采用石墨烯、热塑性聚氨酯（TPU）复合改性聚氨酯注浆材料,并添加少量的粉煤灰、炉底渣及碱性激发剂制备一种低密度、高强度、快硬性的TPU/石墨烯改性聚氨酯注浆材料。借助聚氨酯弹性体材料密度测试仪、万能材料试验机、渗透系数测试仪、荧光显微镜对TPU/石墨烯改性聚氨酯注浆材料的密度、膨胀倍数、抗压强度、阻燃性能、渗透系数及微观形貌进行表征,深入分析了石墨烯和TPU的种类和含量对聚氨酯注浆材料基本物理性能、力学性能及微观结构的影响。结果表明,TPU/石墨烯改性聚氨酯注浆材料的密度为0.24~1.25 g/cm³,膨胀倍数最高可达38倍,抗压强度为15.0~43.8 MPa,相比普通聚氨酯注浆材料,改性聚氨酯注浆材料抗压强度提升1倍以上。酒精灯燃烧试验显示注浆材料无焰燃烧时间均小于20 s。石墨烯和TPU均可提高聚氨酯的强度和耐久性,改善TPU的微观形貌。TPU/石墨烯改性聚氨酯注浆材料表现出良好的强度、耐久性及弹性,是一种性能优异的注浆材料。     

Graphene and Functionalized Graphene Supported Platinum Catalyst for PEMFC

The graphene was synthesized by chemical oxidation followed by thermal exfoliation of natural graphite. The functionalized graphene (FG) was prepared by chemical treatment of the synthesized graphene. The as‐synthesized graphene and FG were characterized and used as Pt support materials. The 20 wt.% Pt/G and 20 wt.% Pt/FG catalysts were prepared by precipitation method. The prepared catalysts were characterized for particle size using X‐ray diffraction, surface morphology, electrochemical performance, and stability using cyclic voltammetry. The electrochemical surface area of the FG supported platinum catalyst was found to be more than 45% as compared to the commercial carbon supported platinum catalyst. The stability of the developed catalyst (Pt/G and Pt/FG) was significantly higher than the commercial Pt/C. The membrane electrode assembly was developed using the catalysts and tested in a PEMFC. The maximum power densities of the fuel cell were found to be 314, 426, and 455 mW cm^–2 using Pt/C, Pt/G, and Pt/FG, respectively.     

石墨烯及氧化石墨烯增强PE–UHMW复合材料进展

从力学性能、化学稳定性和摩擦学性能3个方面,叙述了石墨烯及氧化石墨烯增强超高分子量聚乙烯(PE–UHMW)复合材料的研究现状。根据PE–UHMW复合材料所表现出来的优异性能可知,新型复合材料拥有优异的力学性能,在不远的将来将会取代目前广泛使用的交联聚乙烯材料,并将获得举足轻重的地位。     

Graphene oxide nanopaint

Nanostructured materials are receiving growing interest in the development of a number of commercial products. In this study, we have developed a multifunctional graphene oxide (GO) nanopaint by incorporating GO sheets in an alkyd resin with suitable non-toxic additives using ball milling. The drying mechanism of the GO nanopaint has been discussed. Intermolecular cross-linking between GO and the lipid chains in the alkyd resin was studied by Fourier transform infra red spectra, Raman spectra, and X-ray photoelectron spectra, respectively. The prepared GO nanopaint exhibited good corrosion-resistant behavior in both acidic and high-salt-content solutions as examined by the immersion and electrochemical corrosion tests. The GO nanopaint coating possesses a corrosion protection efficiency of about 76% in salt water as estimated from the linear polarization studies. The antibacterial property of the GO nanopaint coated surface was studied against three bacterial strains (Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) and the results showed that GO nanopaint inhibited the bacterial growth on its surface. The in situ biofouling tests demonstrated the inhibition of fouling on the GO nanopaint surface.     

Binding Graphene Sheets Together Using Silicon: Graphene/Silicon Superlattice

We propose a superlattice consisting of graphene and monolayer thick Si sheets and investigate it using a first-principles density functional theory. The Si layer is found to not only strengthen the interlayer binding between the graphene sheets compared to that in graphite, but also inject electrons into graphene, yet without altering the most unique property of graphene: the Dirac fermion-like electronic structure. The superlattice approach represents a new direction for exploring basic science and applications of graphene-based materials.     

石墨烯对聚苯胺/石墨烯复合电极容量的影响研究

石墨烯因其优异的导电性能和巨大的比表面积而被广泛应用于复合材料的研究。本文借助微晶石英天平采用循环伏安法一步电沉积制备了聚苯胺/石墨烯复合材料,其中所用到的石墨烯分散液是电解剥离法制备的。保持苯胺单体的浓度不变,观察改变石墨烯的含量对聚苯胺/石墨烯复合材料的制备的影响。结果表明,制得的复合材料的比电容高达1166 F/g。当苯胺单体浓度不变时,石墨烯的含量越高,循环伏安结果表明其电容性能也越好。所得的聚苯胺/石墨烯复合材料中石墨烯起到了良好的电子传输作用。     

Preparation and Characterization of Novel Poly(Urethane-Imide) Nanocomposite Based on Graphene,Graphene Oxide and Reduced Graphene Oxide

In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4´-diphenylmethane diisocyanate, polypropylene glycol, 3,3’,4,4′-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample.     

Graphene defect polarity dynamics

Topological defects in graphene, such as dislocations and grain boundaries, can produce out-of-plane buckling defects, which can bulge either up or down and, therefore, introduce two different polarities (namely, “up” and “down”). These defects have strong effects on graphene properties. We perform very long-time-scale, temperature accelerated molecular dynamics simulations of these topological defects and observe that they are able to flip polarity through concerted motion of multiple carbon atoms without breaking any covalent bonds; the simulations reveal the polarity flipping transition pathway. Polarity flipping has activation barriers ranging from 0.80 to 1.55 eV – several times lower than those of breaking covalent bonds (e.g., Stone–Wales bond rotations) and implies that flipping can occur over seconds or years, depending on the defect structure. The simulations further show that when multiple defects are present, polarity flipping can propagate through the defects system leading to interesting and complex higher-order polarity changes.     

Biocompatibility of Graphene Oxide

Herein, we report the effects of graphene oxides on human fibroblast cells and mice with the aim of investigating graphene oxides' biocompatibility. The graphene oxides were prepared by the modified Hummers method and characterized by high-resolution transmission electron microscope and atomic force microscopy. The human fibroblast cells were cultured with different doses of graphene oxides for day 1 to day 5. Thirty mice divided into three test groups (low, middle, high dose) and one control group were injected with 0.1, 0.25, and 0.4 mg graphene oxides, respectively, and were raised for 1 day, 7 days, and 30 days, respectively. Results showed that the water-soluble graphene oxides were successfully prepared; graphene oxides with dose less than 20 μg/mL did not exhibit toxicity to human fibroblast cells, and the dose of more than 50 μg/mL exhibits obvious cytotoxicity such as decreasing cell adhesion, inducing cell apoptosis, entering into lysosomes, mitochondrion, endoplasm, and cell nucleus. Graphene oxides under low dose (0.1 mg) and middle dose (0.25 mg) did not exhibit obvious toxicity to mice and under high dose (0.4 mg) exhibited chronic toxicity, such as 4/9 mice death and lung granuloma formation, mainly located in lung, liver, spleen, and kidney, almost could not be cleaned by kidney. In conclusion, graphene oxides exhibit dose-dependent toxicity to cells and animals, such as inducing cell apoptosis and lung granuloma formation, and cannot be cleaned by kidney. When graphene oxides are explored for in vivo applications in animal or human body, its biocompatibility must be considered.     

Graphene based ballistic rectifiers

Despite having the longest mean-free-path of carriers in all electronic materials, it has been virtually impossible to demonstrate graphene ballistic devices due to the rather diffusive and hence random scattering of carriers from the edges. Hence we show that this may not be true in the nonlinear transport regime in a nanodevice called ballistic rectifier. In contrast to a conventional transistor, the ballistic rectifier does not necessarily require a sizable bandgap. Here, we not only demonstrate rectifying effect at room temperature but also indicate that the carrier scattering from graphene edges in the nonlinear regime may be more specularly than previous discovered in the linear regime.     

Graphene nanoribbon ceramic composites

By unzipping multi-walled carbon nanotubes (MWCNTs) it is possible to obtain graphene nanoribbons (GNRs) that could then be used as fillers in ceramic composites. Here we report the fabrication of silicon nitride (Si₃N₄) ceramics with different contents of GNRs by spark plasma sintering. The GNR fillers confer electrical conductivity to the Si₃N₄ composites, following a semiconducting-like behavior at relatively low volume filler concentrations (0.04). In addition, a toughening effect, produced by GNRs bridging the cracks was observed. GNRs appear to be an efficient alternative to graphene-based composites, useful in the fabrication of novel multifunctional ceramic composites.