Photoluminescent nematic liquid crystalline elastomer actuators

Nematic liquid crystalline elastomer (LCE) actuators possessing both photoluminescent (PL) and stimuli-responsive functions were fabricated and studied. PL-dyes (1-pyrenemethyl acrylate and 4-bromo-2,6-bis-(1?-methyl-benzimidazolyl) pyridine loaded with Eu(III) ion) were synthesised and characterised, and then the dyes were mixed with an acrylate side-on liquid crystalline monomer, a cross-linker and a photo-initiator. Through magnetic field alignment, well-defined LCE micropillar PL actuators were fabricated from the mixed samples by a method combining soft lithography and photo-polymerisation/photo-cross-linking. Microscopic observations indicated that the LCE micropillars showed reversible thermomechanical deformation at the nematic-to-isotropic transition temperature. During the reversible contraction and extension process, the LCE actuator containing 1-pyrenemethyl moieties showed stable photoluminescence, while for the LCE actuator doped with 4-bromo-2,6-bis-(1-methyl-benzimidazolyl)pyridine/Eu(III) complex, the PL emission was quenched at about 100°C, which was before the pillars contraction occurring at a higher temperature. When cooled down to room temperature, the contracted LCE micropillars recovered their original shape and the initial PL emission state. The micron-sized LCE actuators can be used for thermomechanical devices and machines with different PL functions at the same time.     

Binary Metal Oxide Adsorbed Graphene Modified Glassy Carbon Electrode for Detection of Riboflavin

Tungsten oxide (W) decorated titanium oxide (T) adsorbed onto a graphene (Gr) and modified the glassy carbon electrode for the electrochemical quantification of riboflavin (RF) in edible food and pharmaceuticals. For comparison, nanocomposites are formed using graphene oxide (GO), reduced graphene oxide (rGO) and pure graphite (G) sheets to study the electrochemical activities towards riboflavin. The ternary WTGr modified GCE shows the highest electrocatalytic activity due to synergetic interactions between the metal oxide and graphene. The electrochemical observations are supported by the SEM, HRTEM, XRD, UV-Vis, Zeta potential (ζ) and size data. The sensor shows a wide linear range 20 nM–2.5 μM with a detection limit 25.24 nM and sensitivity (4.249×10⁻⁸ A/nM). The fabricated sensor is validated in real samples.     

Enhanced catalytic performance on the thermal decomposition of TKX-50 by Fe3O4 nanoparticles highly dispersed on rGO

Journal of Thermal Analysis and Calorimetry - Fe3O4/reduced graphene oxide (Fe3O4/rGO) nanocomposite has been successfully fabricated using a modified interface solvothermal method and...     

腰接型侧链液晶弹性体研究进展

液晶弹性体是交联型液晶大分子,兼具液晶取向有序性和交联聚合物熵弹性等特性,在传感器、触发器、微流体装置和仿生器件等方面具有很好的应用前景.制备液晶弹性体的微结构,探索其独特的刺激响应性,是目前液晶弹性体研究的重要方向.侧链液晶弹性体的液晶相态类型取决于其液晶基元和主链的连接方式.腰接型侧链液晶弹性体倾向于形成向列型液晶相,具有较快的响应速度和形变程度,是一类独特的液晶弹性体.本文重点介绍腰接型液晶弹性体微结构(如微米柱、微米线等)的制备;利用金纳米粒子的光热转换效应,实现液晶弹性体光响应性的新途径;以及腰接型侧链液晶弹性体仿生微结构的功能性等.同时还对该领域的发展前景进行了展望.     

Prussian Blue/Reduced Graphene Oxide Composite for the Amperometric Determination of Dopamine and Hydrogen Peroxide

Prussian blue has significant application for the construction of electrochemical biosensors. In this work, Prussian blue-reduced graphene oxide modified glass carbon electrodes were successfully fabricated using electrochemical deposition. The high surface area of graphene oxide enhanced the deposition of Prussian blue and the resulting electrocatalytic activity. Infrared spectroscopy and scanning electron microscopy showed that the relatively porous Prussian blue was on the surface of reduced graphene oxide. Cyclic voltammetry showed that Prussian blue-coated reduced graphene oxide composite films improved electron transfer compared to Prussian blue films. The Prussian blue-reduced graphene oxide composite film provided higher response for the reduction of hydrogen peroxide and the oxidation of dopamine compared with the Prussian blue film due to synergistic effects between the reduced graphene oxide and Prussian blue particles. The sensitivity of the electrode was 0.1617 µA µM^?1 cm^?2. The linear dynamic range extended from 0.5 µM to 0.7 mM dopamine with a limit of detection equal to 125 nM. This work provided a versatile strategy for the design and construction of sensitive amperometric sensors with robust electrocatalytic behavior.     

Electrochemistry at chemically modified graphenes

Electrochemical applications of graphene are of great interest to many researchers as they can potentially lead to crucial technological advancements in fabrication of electrochemical devices for energy production and storage, and highly sensitive sensors. There are many routes towards fabrication of bulk quantities of chemically modified graphenes (CMG) for applications such as electrode materials. Each of them yields different graphene materials with different functionalities and structural defects. Here, we compare the electrochemical properties of five different chemically modified graphenes: graphite oxide, graphene oxide, thermally reduced graphene oxide, chemically reduced graphene oxide, and electrochemically reduced graphene oxide. We characterized these materials using transmission electron microscopy, Raman spectroscopy, high-resolution X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry, which allowed us to correlate the electrochemical properties with the structural and chemical features of the CMGs. We found that thermally reduced graphene oxide offers the most favorable electrochemical performance among the different materials studied. Our findings have a profound impact for the applications of chemically modified graphenes in electrochemical devices.     

Cobalt phthalocyanine-graphene complex for electro-catalytic oxidation of dopamine

Cobalt phthalocyanine-graphene(CoPc-Gr) complex are fabricated through π-π interaction of each components,with CoPc adsorbed/inserted on/in the graphene sheets.The obtained complex could be used in the electro-chemical detection of various medicines.CoPc-Gr modified glassy electrode shows excellent response to the electro-oxidation of dopamine(DA) and ascorbic acid(AA),much better than those of CoPc,graphene oxide(GrO) or graphene(Gr) modified electrode.Significantly,the detection of dopamine is a diffusion-controlled process,highly selective,and has a low detection limit and broad linear range.     

Voltammetric determination of nitric oxide using a glassy carbon electrode modified with a nanohybrid consisting of myoglobin,gold nanorods,and reduced graphene oxide

Microchimica Acta - Myoglobin-modified gold nanorods incorporating reduced graphene oxide (rGO) were fabricated and deposited on a glassy carbon electrode (GCE) to obtain a sensor for nitric oxide...     

A Sensitive and Selective Nitrite Detection in Water Using Graphene/Platinum Nanocomposite

A glassy carbon electrode modified with reduced graphene oxide and platinum nanocomposite film was developed simply by electrochemical method for the sensitive and selective detection of nitrite in water. The electrochemical reduction of graphene oxide (GO) efficiently eliminates oxygen‐containing functional groups. Pt nanoparticles were electrochemically and homogeneously deposited on the ErGO surface. Field emission scanning electron microscopy (FE‐SEM), Raman spectroscopy, attenuated total reflectance‐fourier transform infrared spectroscopy (ATR‐FTIR), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) were used to examine the surface morphology and electrocatalytic properties of the Pt‐ErGO nanocomposite film‐modified electrode surface. The fabricated nitrite sensor showed good electrochemical performance with two linear ranges; one from 5 to 100 µM (R²=0.9995) and the other from 100 to 1000 µM (R²=0.9972) and a detection limit of 0.22 µM. The proposed sensor was successfully applied for the detection of nitrite in tap water samples which proves performance of the Pt‐ErGO nanocomposite films.     

Determination of Sudan I Using Electrochemically Reduced Graphene Oxide

Electrochemically reduced graphene oxide (ER-GO) was prepared by reducing exfoliated graphene oxide sheets on a glassy carbon electrode (GCE). The voltammetric responses of Sudan I-IV were studied at the ER-GO modified GCE (ER-GO/GCE). Compared with chemically reduced graphene oxide (CR-GO) modified electrode (CR-GO/GCE), ER-GO/GCE showed higher voltammetric responses to Sudan I. The electrode had a linear response to Sudan I in the range of 0.04–8.0 µmol L^?1 and a detection limit of 0.01 µmol L^?1. The real sample determination indicated that the proposed method was reliable, effective, and sufficient.     

Reduced Graphene Oxide/Carbon Nanotube/Gold Nanoparticles Nanocomposite Functionalized Screen‐Printed Electrode for Sensitive Electrochemical Detection of Endocrine Disruptor Bisphenol A

We fabricated a highly sensitive electrochemical sensor for the determination of bisphenol A (BPA) in aqueous solution by using reduced graphene oxide (RGO), carbon nanotubes (CNT), and gold nanoparticles (AuNPs)‐modified screen‐printed electrode (SPE). GO/CNT nanocomposite was directly reduced to RGO/CNT on SPE at room temperature. AuNPs were then electrochemically deposited in situ on RGO/CNT‐modified SPE. Under optimized conditions, differential pulse voltammetry (DPV) produced linear current responses for BPA concentrations of 1.45 to 20 and 20 to 1,490 nM, with a calculated detection limit of an ultralow 800 pM. The sensor response was unaffected by the presence of interferents such as phenol, p‐nitrophenol, pyrocatechol, 2,4‐dinitrophenol, and hydroquinone.     

KH-570功能化石墨烯的制备与表征

采用Hummers法对天然石墨进行氧化处理制备了氧化石墨烯,通过γ-甲基丙烯酰氧丙基三甲氧基硅烷与氧化石墨烯反应得到功能化氧化石墨烯,然后在水合肼的作用下制备了功能化石墨烯。未烘干的功能化石墨烯在超声处理下,能稳定分散在体积比为9∶1(V/V)的乙醇/水、丙酮/水或N,N-二甲基甲酰胺/水的混合溶剂中。用傅立叶变换红外光谱、原子力显微镜、X射线光电子能谱及X射线衍射对样品结构、形貌进行了分析。结果表明,KH-570上的硅氧烷与氧化石墨烯上的羟基发生了反应,经水合肼还原后,功能化石墨烯的无序度增加,层间距也比功能化氧化石墨烯的缩小了。功能化石墨烯在DMF/水中呈高度剥离状态,片层厚度为1.1～2.3 nm。     

Preparation of arginine‐modified reduced graphene oxide composite filled in an on‐line solid‐phase extraction disk and its application in the analysis of heterocyclic aromatic amines

An arginine‐modified reduced graphene oxide composite was prepared in an on‐line solid‐phase extraction disk and coupled to high‐performance liquid chromatography for the re‐enrichment of heterocyclic aromatic amines. The synthetic composite presented an excellent adsorption capability because of the ultrahigh active surface area of graphene and the abundant alkaline groups of arginine. The adsorption capacity of it was 52.7 mg 2‐amino‐3‐methyl‐imidazo[4,5‐f]‐quinoline per gram, nearly twice that of threonine‐modified reduced graphene oxide composite, glutamic acid modified reduced graphene oxide composite, and reduced graphene oxide. This on‐line method was successfully applied to the detection of a series of heterocyclic aromatic amines in beef jerky. After clean‐up and re‐enrichment of the on‐line solid‐phase extraction disk, the chromatographic background of the sample was low and the shape of chromatographic peaks was sharp. The method detection limit was in the range of 0.30–0.49 ng/g, and the recovery was in the range of 82.0–111.5%.     

Inherent Electrochemistry and Activation of Chemically Modified Graphenes for Electrochemical Applications

Graphene research is currently at the frontier of electrochemistry. Many different graphene‐based materials are employed by electrochemists as electrodes in sensing and in energy‐storage devices. Because the methods for their preparation are inherently different, graphene materials are expected to exhibit different electrochemical behaviors depending on the functionalities and density of defects present. Electrochemical treatment of these “chemically modified graphenes” (CMGs) represents an easy approach to alter surface functionalities and consequently tune the electrochemical performance. Herein, we report a preliminary electrochemical characterization of four common chemically modified graphenes, namely: graphene oxide, graphite oxide, chemically reduced graphene oxide, and thermally reduced graphene oxide. These CMGs were compared with graphite as a reference material. Cyclic voltammetry was used to ascertain the chemical functionalities present and to understand the potential ranges in which the materials were electroactive. Electrochemical treatment with either an oxidative or a reductive fixed potential were then carried out to activate these chemically modified graphenes. The effects of such electrochemical treatments on their electrocatalytic properties were then investigated by cyclic voltammetry in the presence of well‐known redox probes, such as [Fe(CN)₆]^4?/3?, Fe^3+/2+, [Ru(NH₃)₆]^2+/3+, and ascorbic acid. Thermally reduced graphene oxide exhibited the best electrochemical behavior amongst all of the CMGs, with the fastest rate of heterogeneous electron transfer (HET) and the lowest overpotentials. These findings will have far‐reaching consequences for the evaluation of different CMGs as electrode materials in electrochemical devices.     

A composite polyaniline/graphene–coated polyamide6 nanofiber mat for electrochemical applications

In this study, polyamide6 (PA6) nanofiber mats were fabricated through the electrospinning process. The nanofibers were coated by polyaniline (PANI) using the in situ polymerization of aniline in the presence of graphene oxide. The composite of the PANI/graphene oxide–coated nanofiber mat was treated with hydrazine monohydrate to reduce graphene oxide to graphene, and this was followed by the reoxidation of PANI. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), thermal gravimetric analysis (TGA), tensile strength tests, electrical conductivity measurements, cyclic voltammetry (CV), and charge/discharge measurements were conducted on the composite PA6/graphene nanofiber mats. It was found that the surface of the PA6 nanofibers was coated uniformly with the granular PANI and graphene oxide. Besides, the composite nanofibers showed good tensile and thermal properties. Their electrical conductivity and specific capacitance, when used as a separator in the cell, were 1.02 × 10^?4 S/cm and 423.28 F/g, respectively. Therefore, the composite PANI/reduced graphene oxide–coated PA6 nanofiber mats could be regarded as suitable candidates for application in energy storage devices.     

Facile decoration of TiO2 nanoparticles on graphene for solar degradation of organic dye

The reduced graphene oxide is interesting material for the synthesis of TiO₂-based photocatalyst. In the present investigation, blackberry fruit, which contains high levels of anthocyanins and other phenolic compounds, was employed as a reducing agent mainly due to its high antioxidant capacity. The nano-crystalline TiO₂ was decorated on different amounts of graphene oxide with sol–gel method and then the photocatalytic activity for degradation of cationic dye was evaluated by UV spectroscopy to achieve the optimum content of graphene oxide. The decoration of anatase nanoparticles on prepared reduced graphene oxide was investigated by X-ray diffraction, scanning and transmission electron microscopy techniques. The new composite gives significantly higher activity when is compared to the compositions fabricated by graphene oxide. The compact layer provides a large TiO₂-graphene contact area and reduces the electron recombination. The decoration of TiO₂ nanoparticles, 5–10 nm, on the graphene oxide reduced by blackberry juice further improves the dye removal. The results imply that the nanoparticle decoration is the key strategy to increase the degradation capacity.     

A novel ZnO/reduced graphene oxide and Prussian blue modified carbon paste electrode for the sensitive determination of Rutin

Science China Chemistry - A carbon paste modified sensor based on a novel composite of zinc oxide nanoparticles deposited on reduced graphene oxide (ZnO-rGrO) and Prussian blue (PB) was drop-cast...     

Synthesis and properties of near IR induced self-healable polyurethane/graphene nanocomposites

A series of self-healable polyurethane (SHPU)/modified graphene (MG) nanocomposites were synthesized from poly(tetramethylene glycol) (PTMG) and 4,4′-methylene diphenyl diisocyanate (MDI) with minute amounts (0–1 wt%) of MG which was chemically modified graphene oxide (GO) with phenyl isocyanate and reduced in the presence of phenylhydrazine.     

石墨烯纳米载药体系的制备及对人口腔鳞癌细胞杀伤效果

利用化学氧化还原法制备了氧化石墨烯,进一步超声破碎剥离,得到纳米氧化石墨烯,并对其进行聚乙二醇(PEG)的功能化修饰后载药顺铂。 采用扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)、傅立叶变换红外光谱(FTIR)对石墨烯纳米载药体系进行表征,细胞存活率实验(MTT)法检验石墨烯纳米载药体系对人口腔鳞癌(KB)细胞的杀伤作用。 结果表明,石墨烯纳米载药体系对顺铂的负载率为42.4%,聚乙二醇修饰后可以降低纳米氧化石墨烯的细胞毒性并提高生物相容性,对KB细胞具有双重的杀伤作用,为纳米氧化石墨烯在肿瘤治疗的临床应用提供了理论依据。