Graphene Nanocomposites Prepared From Blends of Polymer Latex with Chemically Reduced Graphite Oxide Dispersions

Graphene nanocomposites are prepared by chemical reduction of graphite oxide (GO) dispersion with vitamin C in the presence of SAN latex followed by melt compounding. In this process, GO is well dispersed in an aqueous SAN emulsion before reduction. During reduction the SAN latex is adsorbed on the graphene sheets of the chemically reduced GO (CRGO). After melt compounding of such hybrid particles with SAN, the nanocomposites show uniform dispersion of CRGO in SAN resulting in improved stiffness with respect to SAN/graphite. The reduction of GO in the presence of polymer latex represents a versatile route to graphene masterbatches and does not require either drying of GO or thermal GO expansion at high temperatures.

     

功能化还原氧化石墨烯/天然橡胶导热复合材料的性能研究

采用2-巯基苯并咪唑(防老剂MB,以下简称MB)对氧化石墨烯(GO)进行还原及功能化,同时与采用抗坏血酸(VC)对GO进行还原对比,分别制得MB还原氧化石墨烯(rGO-MB)和VC还原氧化石墨烯(rGO-VC),并采用胶乳共混法制备rGO-MB/NR和rGO-VC/NR复合材料,对其性能进行研究。结果表明:MB成功还原了GO,MB接枝到了GO上;与rGO-VC/NR复合材料相比,rGO-MB/NR复合材料具有较低的Payne效应和较高的结合胶含量,拉伸强度和导热性能均明显提高。     

Thermal and Barrier Properties of Organoclay-filled Polysulfone Nanocomposites

Organo-modified fluorohectorite (OFH) clay-filled polysulfone (PSf) nanocomposites were prepared by a solution casting method. The dispersion of OFH clay in PSf nanocomposites was investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy (TEM). Thermal analysis revealed that incorporation of organoclay increased the thermal stability and glass transition temperature (T_g) of nanocomposites. The barrier properties of the nanocomposites studied were found to be significantly improved. It is worth mentioning that the improved thermal stability and barrier performance of these nanocomposites with the addition of organoclay in PSf matrix obviously offers immense potential in industrial and automobile applications.     

The Preliminary Study on the Proapoptotic Effect of Reduced Graphene Oxide in Breast Cancer Cell Lines

Breast cancer is the most common cancer diagnosed in women, however traditional therapies have several side effects. This has led to an urgent need to explore novel drug approaches to treatment strategies such as graphene-based nanomaterials such as reduced graphene oxide (rGO). It was noticed as a potential drug due to its target selectivity, easy functionalisation, chemisensitisation, and high drug-loading capacity. rGO is widely used in many fields, including biological and biomedical, due to its unique physicochemical properties. However, the possible mechanisms of rGO toxicity remain unclear. In this paper, we present findings on the cytotoxic and antiproliferative effects of rGO and its ability to induce oxidative stress and apoptosis of breast cancer cell lines. We indicate that rGO induced time- and dose-dependent cytotoxicity in MDA-MB-231 and ZR-75-1 cell lines, but not in T-47D, MCF-7, Hs 578T cell lines. In rGO-treated MDA-MB-231 and ZR-75-1 cell lines, we noticed increased induction of apoptosis and necrosis. In addition, rGO has been found to cause oxidative stress, reduce proliferation, and induce structural changes in breast cancer cells. Taken together, these studies provide new insight into the mechanism of oxidative stress and apoptosis in breast cancer cells.     

改性热还原氧化石墨烯/尼龙纳米复合材料的制备及性能

经溶液共混法成功制备了离子液体改性热还原氧化石墨烯/三元共聚尼龙(IL-TRGO/CO-PA)纳米复合材料,测试分析表明IL-TRGO能明显改善纳米复合材料的性能。XRD和SEM分析表明:当TRGO的含量不高于0.75%时,IL-TRGO片层可以均匀地分散在CO-PA基体中。DSC和TGA分析表明:IL-TRGO能够提高纳米复合材料的结晶温度和热稳定性,但降低了其玻璃化转变温度。力学性能测试表明:TRGO能够提高复合材料的力学性能,当TRGO含量为0.5%时,纳米复合材料的拉伸强度、屈服强度和断裂伸长率分别提高了82.1%、129%和22.7%;当TRGO含量为0.75%时,纳米复合材料的屈服强度提高了161.6%。     

In Situ Synthesis of Reduced Graphene Oxide and Gold Nanocomposites for Nanoelectronics and Biosensing

In this study, an in situ chemical synthesis approach has been developed to prepare graphene–Au nanocomposites from chemically reduced graphene oxide (rGO) in aqueous media. UV–Vis absorption, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy were used to demonstrate the successful attachment of Au nanoparticles to graphene sheets. Configured as field-effect transistors (FETs), the as-synthesized single-layered rGO-Au nanocomposites exhibit higher hole mobility and conductance when compared to the rGO sheets, promising its applications in nanoelectronics. Furthermore, we demonstrate that the rGO-Au FETs are able to label-freely detect DNA hybridization with high sensitivity, indicating its potentials in nanoelectronic biosensing.     

Eco-Friendly Synthesis of Graphene Oxide Reinforced Hydroxypropyl Methylcellulose/Polyvinyl Alcohol Blend Nanocomposites Filled with Zinc Oxide Nanoparticles for High-k Capacitor Applications

Polymer/inorganic nanocomposites comprising of hydroxypropyl methylcellulose and polyvinyl alcohol as a polymer matrix and unique combination of graphene oxide and zinc oxide nanoparticles as fillers have been prepared using colloidal processing technique and characterized using various analytical methods. The dielectric properties of the nanocomposites are investigated using impedance analyzer. The nanocomposites show improvement in the dielectric properties compared to hydroxypropyl methylcellulose/polyvinyl alcohol (50/50) blends, which results from the homogeneous dispersion of fillers into the polymer matrix. The results indicate that these nanocomposites have a potential to meet the technological demands of high-k dielectrics and/or embedded capacitors.     

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.     

Synthesis and Bioactivity of Reduced Graphene Oxide/Alumina‐Noble Metal Nanocomposite Flakes

The aim of this study was to describe the modification of the bioactivity of Al₂O₃‐noble metal (Me = Ag, Au, or Pd) composite nanoparticles by the addition of graphene oxide and the formation of a RGO/Al₂O₃‐Me nanocomposite system. The nanocomposite flakes and Al₂O₃‐Me composite nanoparticles were widely characterized. The antibacterial effect was observed only for Al₂O₃‐Ag composite nanoparticles and RGO/Al₂O₃‐Ag nanocomposite flakes, while, in the case of RGO/Al₂O₃‐Ag, a more evident antibacterial effect against Staphylococcus aureus bacteria was observed compared with Al₂O₃‐Ag. In the case of other noble metals (Au, Pd), a slight growth‐stimulating effect was revealed for particular bacterial strains.     

High-Performance and Biobased Polyamide/Functionalized Graphene Oxide Nanocomposites through In Situ Polymerization for Engineering Applications

In this study, biobased polyamide/functionalized graphene oxide (PA-FGO) nanocomposite is developed using sustainable resources. Renewable PA is synthesized via polycondensation of hexamethylenediamine (HMDA) and biobased tetradecanedioic acid. Furthermore, GO is functionalized with HMDA to improve its compatibility with biobased PA and in situ polymerization is employed to obtain homogeneous PA-FGO nanocomposites. Compatibility improvement provides simultaneous increases in the tensile strength, storage modulus, and conductivity of PA by adding only 2 wt% FGO (PA-FGO2). The tensile strength and storage modulus of PA-FGO2 nanocomposite are enhanced dramatically by ≈50% and 30%, respectively, and the electrical conductivity reached 3.80 × 10^–3 S m⁻¹. In addition, rheology testing confirms a shear-thinning trend for all samples as well as a significant enhancement in the storage modulus upon increasing the FGO content due to a rigid network formation and strong polymer-filler interactions. All these improvements strongly support the excellent compatibility and enhanced interfacial interactions between organic–inorganic phases resulting from GO surface functionalization. It is expected that the biobased PA-FGO nanocomposites with remarkable thermomechanical properties developed here can be used to design high-performance structures for demanded engineering applications.     

CuxCo1-xFe2O4 (x = 0.33, 0.67, 1) Spinel Ferrite Nanoparticles Based Thermoplastic Polyurethane Nanocomposites with Reduced Graphene Oxide for Highly Efficient Electromagnetic Interference Shielding

Cu_xCo_1-xFe₂O₄ (x = 0.33, 0.67, 1)-reduced graphene oxide (rGO)-thermoplastic polyurethane (TPU) nanocomposites exhibiting highly efficient electromagnetic interference (EMI) shielding were prepared by a melt-mixing approach using a microcompounder. Spinel ferrite Cu_0.33Co_0.67Fe₂O₄ (CuCoF1), Cu_0.67Co_0.33Fe₂O₄ (CuCoF2) and CuFe₂O₄ (CuF3) nanoparticles were synthesized using the sonochemical method. The CuCoF1 and CuCoF2 exhibited typical ferromagnetic features, whereas CuF3 displayed superparamagnetic characteristics. The maximum value of EMI total shielding effectiveness (SE_T) was noticed to be 42.9 dB, 46.2 dB, and 58.8 dB for CuCoF1-rGO-TPU, CuCoF2-rGO-TPU, and CuF3-rGO-TPU nanocomposites, respectively, at a thickness of 1 mm. The highly efficient EMI shielding performance was attributed to the good impedance matching, conductive, dielectric, and magnetic loss. The demonstrated nanocomposites are promising candidates for a lightweight, flexible, and highly efficient EMI shielding material.     

石墨烯纳米复合材料的制备与应用研究进展

石墨烯是近年被发现和合成的一种新型二维碳质纳米材料.由于其独特的结构和新奇的物化性能,在改善复合材料的热性能、力学性能和电性能等方面具有很大的潜力,已成为纳米复合材料研究的热点.综述了石墨烯纳米复合材料的制备与应用研究进展,并对石墨烯纳米复合材料的发展前景进行了展望.     

Luminescence,Paramagnetic, and Electrochemical Properties of Copper Oxides-Decorated TiO2/Graphene Oxide Nanocomposites

The properties of newly synthesized Cu₂O/CuO-decorated TiO₂/graphene oxide (GO) nanocomposites (NC) were analyzed aiming to obtain insight into their photocatalytic behavior and their various applications, including water remediation, self-cleaning surfaces, antibacterial materials, and electrochemical sensors. The physico-chemical methods of research were photoluminescence (PL), electron paramagnetic resonance (EPR) spectroscopy, cyclic voltammetry (CV), and differential pulse voltammetry (DPV). The solid samples evidenced an EPR signal that can be attributed to the oxygen-vacancy defects and copper ions in correlation with PL results. Free radicals generated before and after UV-Vis irradiation of powders and aqueous dispersions of Cu₂O/CuO-decorated TiO₂/GO nanocomposites were studied by EPR spectroscopy using two spin traps, DMPO (5,5-dimethyl-1-pyrroline-N-oxide) and CPH (1-hydroxy-3-carboxy-2,2,5,5-tetramethylpyrrolidine), to highlight the formation of hydroxyl and superoxide reactive oxygen species, respectively. The electrochemical characterization of the NC modified carbon-paste electrodes (CPE) was carried out by CV and DPV. As such, modified carbon-paste electrodes were prepared by mixing carbon paste with copper oxides-decorated TiO₂/GO nanocomposites. We have shown that GO reduces the recombination process in TiO₂ by immediate electron transfer from excited TiO₂ to GO sheets. The results suggest that differences in the PL, respectively, EPR data and electrochemical behavior, are due to the different copper oxides and GO content, presenting new perspectives of materials functionalization.     

Effects of Graphene Oxide and Reduced Graphene Oxide Nanostructures on CD4+ Th2 Lymphocytes

The activation of T helper (Th) lymphocytes is necessary for the adaptive immune response as they contribute to the stimulation of B cells (for the secretion of antibodies) and macrophages (for phagocytosis and destruction of pathogens) and are necessary for cytotoxic T-cell activation to kill infected target cells. For these issues, Th lymphocytes must be converted into Th effector cells after their stimulation through their surface receptors TCR/CD3 (by binding to peptide-major histocompatibility complex localized on antigen-presenting cells) and the CD4 co-receptor. After stimulation, Th cells proliferate and differentiate into subpopulations, like Th1, Th2 or Th17, with different functions during the adaptative immune response. Due to the central role of the activation of Th lymphocytes for an accurate adaptative immune response and considering recent preclinical advances in the use of nanomaterials to enhance T-cell therapy, we evaluated in vitro the effects of graphene oxide (GO) and two types of reduced GO (rGO15 and rGO30) nanostructures on the Th2 lymphocyte cell line SR.D10. This cell line offers the possibility of studying their activation threshold by employing soluble antibodies against TCR/CD3 and against CD4, as well as the simultaneous activation of these two receptors. In the present study, the effects of GO, rGO15 and rGO30 on the activation/proliferation rate of these Th2 lymphocytes have been analyzed by studying cell viability, cell cycle phases, intracellular content of reactive oxygen species (ROS) and cytokine secretion. High lymphocyte viability values were obtained after treatment with these nanostructures, as well as increased proliferation in the presence of rGOs. Moreover, rGO15 treatment decreased the intracellular ROS content of Th2 cells in all stimulated conditions. The analysis of these parameters showed that the presence of these GO and rGO nanostructures did not alter the response of Th2 lymphocytes.     

Thermo‐Mechanical Degradation of LDPE‐Based Nanocomposites

Thermo‐mechanical degradation of LDPE‐based nanocomposites was studied by mainly investigating the rheological properties. For all of the investigated processing conditions, the viscosity of the nanocomposites was higher than that of the pure‐LDPE matrix, but on increasing the severity of the mixing conditions, the difference between the viscosity of the nano‐filled polymer and that of the pure LDPE decreased. The X‐ray traces of the nanocomposites suggest that intercalation has been achieved during the melt, when less‐severe processing conditions were used. At severe processing conditions (longer mixing time, high temperature and shear stress) the thermo‐mechanical degradation was accelerated, possibly due to the loss of mass from the organoclay galleries. The variations of the viscosity in the presence of two organo‐modified montmorillonite (MMt) clays were compared to the ones observed with a MMt clay at different processing conditions.

     

Synergetic Effects of Graphene Oxide and Clay on the Microstructure and Properties of HIPS/Graphene Oxide/Clay Nanocomposites

In this paper, double-network structure nanocomposite with improved mechanical and thermal properties were prepared using high-impact polystyrene as a matrix phase, clay and graphene oxide as effective reinforcing fillers through a facile solution intercalation method. The structure and morphology of nanocomposites were characterized by transmission electron microscopy, scanning electron microscopy, X-ray diffraction analysis, and the synergetic effects of clay and graphene oxide on the final properties were investigated using tensile, dynamic mechanical thermal analysis (DMTA) and thermogravimetric analysis (TGA) analysis. Mechanical analysis showed that the combination of graphene oxide and clay exerted a favorable synergistic effect on the tensile modulus and the yield strength of the ternary composite that are greatly improved as compared with neat high-impact polystyrene, high-impact polystyrene/graphene oxide, and high-impact polystyrene/clay binary composites due to the double-network structure formation between the nanofillers as confirmed by the direct morphological observations using transmission electron microscopy and scanning electron microscopy analysis. The viscoelastic behavior showed that storage modulus of ternary composite significantly improvement over than that of the pure matrix, high-impact polystyrene/graphene oxide and high-impact polystyrene/clay while network structure made. TGA and DMTA measurements also demonstrated that thermal stability of high-impact polystyrene matrix modified by graphene oxide and clay slightly enhanced during the creation of dual network structure of graphene oxide and clay. Our data suggest a potential application for the combination of graphene oxide and clay in graphene-based composite materials.     

尼龙12/氧化石墨烯纳米复合粉末的制备及性能

在高分子材料中引入纳米填料制备选择性激光烧结(SLS)复合粉末能够有效增强烧结件的性能。通过改进的Hummers方法辅以超声剥离制备氧化石墨烯(GO),通过溶剂沉淀法制备尼龙12/氧化石墨烯(PA12/GO)纳米复合粉末。利用傅立叶变换红外光谱、透射电子显微镜、X射线衍射、扫描电子显微镜等手段对材料结构进行了表征,并对复合粉末的力学性能和热学性能进行了测试。结果表明,GO能均匀分散在PA12基体中,PA12/GO纳米复合材料的拉伸强度、弯曲强度、弯曲弹性模量、维卡软化温度分别提高了18.9%,8.3%,5.4%,6.8%,热失重曲线显示当温度为450℃时,PA12/GO质量保持率为85.25%,而纯PA12仅为65.17%。PA12/GO纳米复合粉末为选择性激光烧结提供了一种性能良好的粉末材料。     

Application of SrRuO3 Nanoparticles Supported with Reduced Graphene Oxide for Degradation of Thiophene Under Visible Light Irradiation

Journal of Inorganic and Organometallic Polymers and Materials - The existence of thiophene (TP) in fuel processing technology is considered a real threat to the environment. So the development of...     

聚乳酸/氧化石墨烯纳米复合材料的界面调控与性能研究

分别以乙二胺（EDA）、十二烷基胺（DA）和十八烷基胺（ODA）修饰的氧化石墨烯（GO）为填料,制备了具有不同界面结构的功能化聚乳酸(PLA)/氧化石墨烯(FGO)纳米复合薄膜。采用X射线衍射分析、扫描电子显微镜、热失重分析、差示扫描量热法对复合薄膜的材料结构、微观形貌和热性能进行表征,并研究了其力学性能及气体渗透性。结果表明,随着GO表面接枝分子链的增长,复合材料的热稳定性、力学性能及气体阻透性能提高;3种FGO中,GO-g-ODA改性体系的综合性能最佳,当其添加量为0.5 %（质量分数,下同）时,复合材料的拉伸强度和断裂伸长率分别达到88.52 MPa和9.68 %;氧气渗透系数由原来的4.21×10^13 cm3·cm/(cm2·s·Pa)下降到1.172×10^14 cm3·cm/(cm2·s·Pa),约下降了97.2 %;此外,功能化石墨烯的加入使复合材料的热稳定性提高。