Coating and filling of carbon nanotubes with homogeneous magnetic nanoparticles

Magnetic multi-walled carbon nanotube (MWCNT) composites were obtained by decoration of metal oxide nanoparticles on or in carbon nanotubes. The method involved the dispersion of the carbon nanotubes in iron pentacarbonyl Fe(CO)₅ followed by vacuum thermolysis and subsequent oxidation. The magnetic iron oxide particle deposition was always homogeneous and could be controlled selectively on the outer, inner, or both surfaces of MWCNTs by using different MWCNTs. Since the hollow channels remained intact, these MWCNT based composites could find special applications in cellular delivery systems.     

Magnetic field-guided orientation of carbon nanotubes through their conjugation with magnetic nanoparticles

Low intensity magnetic fields (22mT) rendered by a pair of bar magnets have been used to achieve in situ precise orientation of multiwalled carbon nanotubes (MWCNTs) and their directional deposition on solid substrates. The nanotubes were imparted magnetic characteristics through Fe₃O₄ (magnetite) nanoparticles covalently attached to their surface. The side walls of nanotubes were first acid oxidized with H₂SO₄/HNO₃ (3:1 v/v) mixture and amine-functionalized magnetic nanoparticles were then interfaced to ends and side walls of the nanotubes through covalent linkages in the presence of a zero length cross linker, 1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide. Fourier transformed infrared spectroscopic investigations affirmed the functionalization of nanostructures and formation of a magnetic nanohybrid. Transmission electron microscopy results revealed the attachment of nanoparticles along the side walls of MWCNTs. A flow cell was utilized to orient magnetic nanohybrid in the desired direction and also to create thin films of aligned MWCNTs. Further, directional assembly of magnetic MWCNTs at different orientation angles on solid substrates was studied by field emission scanning electron microscopy and optical microscopy. The procedure can be scaled to align CNTs on large surface areas for numerous applications, e.g., nanosensors, field emitters, and composites.     

Decoration of multi-walled carbon nanotubes with silver nanoparticles and investigation on its colloid stability

In this paper, multi-walled carbon nanotubes (MWCNTs) were decorated with silver nanoparticles which have been successfully synthesized by chemical reduction of Ag cations on the acid treated MWCNTs surface by sodium hydroxide. Ag/MWCNTs were characterized by TEM and XRD. The results indicated that silver nanoparticles were homogeneously dispersed on the outer surface of MWCNTs. The dispersibility of pristine, acid treated and decorated carbon nanotubes in distilled water were investigated by zeta potential and optical image. The results revealed that the dispersion of acid treated carbon nanotubes in distilled water was better than those of pristine MWCNTs and Ag/MWCNTs.     

Fabrication of gold nanoparticle/multi walled carbon nanotube hybrids by in situ reaction in water using poly(acryloyl beta-alanine)

Fabrication of a hybrid consists of gold nanoparticles and multi walled carbon nanotubes (MWCNTs) with the help of poly (amino acid) was investigated. Poly(acryloyl beta-alanine) was synthesized by precipitation polymerization in tetrahydrofuran. The polymers were used to form hybrids with MWCNTs in aqueous media. Subsequently, the polymer functionalized MWCNTs were fabricated by in situ formed gold nanoparticles. The fabrication by gold nanoparticles was confirmed by transmission electron microscopic analyses. The fabrication was attempted with different concentrations of lithium auric chloride solutions in the range of 0.1-1.2 mM in water. The lower concentration of the gold precursor solution resulted in the formation and attachment of gold nanoparticles without aggregation while the higher concentration above 1.0 mM led to the aggregation of gold nanoparticles. The gold nanoparticles were observed only on the surface of MWCNTs and none was in the bulk aqueous phase.     

Synthesis and properties of magnetic multi-walled carbon nanotubes loaded with Fe4N nanoparticles

High saturation magnetization (>90 emu/g) multi-walled carbon nanotubes (MWCNTs) and Fe₄N nanoparticles composite were successfully synthesized by gas nitriding at 550 °C. Almost all Fe₄N nanoparticles were evenly distributed inside the carbon nanotubes and formed a special composite microstructure. This composite microstructure shows excellent soft magnetic property, structural stability, and chemical stability at room temperature. The investigations of electromagnetic and microwave absorption performances indicate that microwave absorbing capacity of low frequency band of MWCNTs were greatly improved by addition of Fe₄N nanoparticles.     

Covalent coupling of polyacrylic acid coated magnetic-nanoparticles to multi-wall carbon nanotubes for manipulation targets

This research effort investigated the chemical heterojunction between magnetic nanoparticles coated with polyacrylic acid and multi-wall carbon nanotubes (MWCNTs). Here, magnetic nanoparticles were covalently attached to open-ended nanotubes in the presence of diclohexylcarbodiiimide. Initial evidence demonstrated that short functionalised multi-wall nanotubes can be continuously connected at their terminals ends to build-up relatively large nanostructures. It has also been shown that magnetic-carbon nanotubes (CNTs) systems exhibited defined arrangements due to the influence of magnetic fields. Indeed, linear arrays of CNTs interconnected through magnetic nanoparticles were prone to be manipulated in the presence of a magnetic device. A potential application of these kind of magnetic nanostructures was shown here by successfully manipulating agarose beads in a buffer solution. These results suggest that the use of continuously connected magnetic nanostructures with non-modified sidewall surfaces will find potential applications in the area of bio-sensing, force transduction and cancer screening-manipulation among many others.     

A complete green protocol: wrapping of multiwall carbon nanotubes with silver nanoparticles

Silver nanoparticles have been wrapped on multiwall carbon nanotubes though a green synthesis approach that has advantages over other conventional methods that involve chemical agents associated with environmental toxicity and damage of carbon nanotubes. Acacia was used as a green stabilizer for multiwall carbon nanotubes as well as a stabilizer and reducing agent for silver nanoparticles. Generation of silver-decorated multiwall carbon nanotubes was confirmed by UV-Vis spectrophotometry and X-ray diffraction. Generation of silver nanoparticles (5-10 nm) wrapped on MWCNTs was confirmed by field emission scanning electron microscopy and transmission electron microscopy.     

Preparation, characterization and photocatalytic properties of CdS nanoparticles dotted on the surface of carbon nanotubes

Cadmium sulfide (CdS) nanoparticles dotted on the surface of multiwalled carbon nanotubes (MWCNTs) have been synthesized by the polyol method. The as-prepared materials were characterized by x-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, and Brunauer-Emmett-Teller adsorption analysis. The results indicate that CdS nanoparticles with diameter of 5-8?nm are thickly and uniformly coated on the surface of the MWCNTs. The photodegradation of azo dye using these materials was evaluated by the degradation of Brilliant Red X-3B under visible light. The coated nanotubes show higher photocatalytic activity than both CdS alone and a CdS/activated carbon sample; in addition, there is an optimum content of MWCNTs. The presence of MWCNTs can also hamper the photocorrosion of CdS. The mechanism for the enhancement of MWCNTs on the adsorption and photocatalytic property of CdS is investigated for the first time.     

嵌段共聚物修饰多壁碳纳米管

为了改善多壁碳纳米管的分散性,通过丙烯酸和羟基化多壁碳纳米管的酯化反应将双键引入到碳纳米管的表面,同时利用原子转移自由基聚合合成端基为卤素的苯乙烯-b-甲基丙烯酸羟乙酯嵌段共聚物,并通过对双键的加成反应,将嵌段共聚物引入到多壁碳纳米管的表面,实现了碳纳米管的化学修饰。通过FTIR、TGA和TEM技术对产物进行了表征,结果表明:嵌段共聚物通过共价键接枝到碳纳米管表面,其含量为42.9%,平均约277个碳原子接枝一条聚合物链;修饰后的MW CNTs在乙醇中分散良好。     

纳米镍颗粒填充碳纳米管的制备与磁性能

采用自制的实验装置, 通过阳极弧放电等离子体技术成功制备了Ni纳米颗粒填充的碳纳米管, 利用高分辨透射电子显微镜(HRTEM)、 XRD、 TEM、 X射线能量色散分析谱仪(XEDS)和振动样品磁强计(VSM)等测试手段对样品的化学成分、 形态、 微观结构和磁性能进行了表征。实验结果表明, 采用本文中实验方法能获得大量被纳米金属颗粒填充的碳纳米管, 其内部填充物为面心立方(FCC)结构的纳米Ni颗粒, 外围薄层为石墨碳层。碳纳米管的外径为30~40 nm, 壁厚5~8 nm, 内部填充的纳米颗粒呈球形和椭球形, 粒径均匀, 在管腔内不连续分布。产物具有顺磁特性, 矫顽力是78 Oe, 饱和磁化强度是33 enu/g。     

碳纳米管承载纳米Fe_3O_4颗粒的制备(英文)

采用一种简单又经济的方法将Fe3O4纳米颗粒填充到碳纳米管中。透射电镜(TEM)、扫描电镜(SEM)及其能谱附件(EDX)和X射线多晶衍射(XRD)测试结果表明:Fe3O4纳米颗粒成功地填充到碳纳米管中。材料的磁性能测试结果表明:碳纳米管中填充Fe3O4纳米颗粒后,在常温下具有超顺磁性,其饱和磁化强度由0.35emu/g增大到了13.15emu/g。Fe3O4纳米颗粒填充的碳纳米管可望应用于工程和医学领域。     

Cytotoxicity properties of functionalised carbon nanotubes on pathogenic bacteria

Nanobiotechnology is a promising field concerned with the using of engineered nanomaterials, which leads to the improvement of new human remedial against pathogenic bacteria modalities. In this work, silver nanoparticles (AgNPs) were prepared by an easy, cheap and low‐cost electro‐chemical method. The AgNPs were then loaded successfully on to multi‐walled carbon nanotubes (MWCNTs) using a modified chemical reaction process. The AgNPs on the MWCNTs were well spread and evenly distributed on the surfaces of the long nanotubes with well‐graphitised walls as examined by high‐resolution transmission electron microscopy. X‐ray diffraction and transmission electron microscopy were used for sample characterisation. Good dispersion of AgNPs was obtained on the surface of MWCNTs, resulting in an efficient reactivity of the carbon nanotubes surfaces. Finally, the antibacterial activity of AgNPs/MWCNTs hybrid was evaluated against two pathogenic bacteria Pseudomonas aeruginosa and Staphylococcus aureus exhibited excellent activity.Inspec keywords: nanocomposites, X‐ray diffraction, nanofabrication, nanoparticles, transmission electron microscopy, toxicology, silver, antibacterial activity, microorganisms, nanomedicine, multi‐wall carbon nanotubes, electrochemistryOther keywords: engineered nanomaterials, human remedial, pathogenic bacteria modalities, silver nanoparticles, multiwalled carbon nanotubes, modified chemical reaction process, well‐graphitised walls, high‐resolution transmission electron microscopy, cytotoxicity properties, functionalised carbon nanotubes, carbon nanotube surfaces, nanobiotechnology, low‐cost electrochemical method, AgNP‐MWCNT hybrid, X‐ray diffraction, antibacterial activity, Pseudomonas aeruginosa, Staphylococcus aureus, Ag‐C     

The effect of multi-walled carbon nanotubes/hydroxyapatite nanocomposites on biocompatibility

In the present study, multi-walled carbon nanotubes/hydroxyapatite (MWCNTs/HA) nanocomposites with various MWCNT contents were manufactured by sol-gel processing. The MWCNTs/HA powder was characterized using field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Raman analysis. The results show that the MWCNTs were fully covered with HA nanoparticles and help forming the crystallized hydroxyapatite. In addition, in vitro tests highlighted the excellent biocompatibility of the MWCNTs/HA composite.     

Controllable synthesis and magnetic properties of Fe–Co alloy nanoparticles attached on carbon nanotubes

Fe–Co alloy nanoparticles with different size were attached on the carbon nanotubes through adjusting the ratio of the metal to carbon in the mixed solution of nitrate with Fe:Co = 1:1 (molar ratio) via wet chemistry. X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and energy-dispersive X-ray spectrometry (EDX) indicated that the Fe–Co alloy nanoparticles attached on the surface of carbon nanotubes has body-centered cubic (bcc) structure, with sizes in the range of 13–25 nm and in the shape of spheroids. Magnetization measurements indicated that both the coercivities and the saturation magnetizations altered with size changes of the Fe–Co alloy nanoparticles. The saturation magnetization decreases with decreasing the Fe–Co alloy nanoparticles’ sizes. A decrease in coercivity with increasing Fe–Co size together with a local maximum coercivity at size of ca. 15 nm is visible. A linear relationship between the inverse particle diameter and the coercivity was found for larger particles. These demonstrated that the chemical method here is promising for fabricating Fe–Co alloy nanoparticles coated on carbon nanotubes for magnetic storage applications.     

富勒烯/碳纳米管杂化材料的制备及表征

本文通过一种简易的化学方法成功制备了富勒烯/碳纳米管杂化材料。首先采用强酸氧化处理多壁碳纳米管使其表面产生羟基和羧基等官能基团,再将氧化处理后的碳纳米管与六亚甲基二异氰酸酯反应,通过羟基和羧基基团与异氰酸根的反应对多壁碳纳米管进行修饰,最后利用富勒醇表面的羟基与碳纳米管表面异氰酸之间的反应制备出富勒烯/碳纳米管杂化材料。产品采用傅立叶变换红外光谱(FTIR)、透射电镜(TEM)和热重分析(TGA)等手段进行了分析和表征。结果表明,成功实现了富勒烯与碳纳米管的化学组装。     

高分散多壁碳纳米管增强铝基复合材料的制备(英文)

采用机械合金化技术制备高分散多壁碳纳米管(MWCNTs)-铝(Al)复合材料。将纯度99%的铝粉和质量分数2%的MWCNTs经超声和水平球磨处理使Al颗粒与MWCNTs间产生机械键合力。场发射SEM观察表明,MWCNTs分散在Al薄片的表面,随球磨时间的不同,颗粒大小和形貌各异。采用加压烧结手段将混合粉末加工成块体材料,其微观硬度测试表明,加入MWCNTs后Al基体的机械性能得到提高。     

多壁碳纳米管的表面改性及其在防火涂料中的应用

利用两亲性聚合物对多壁碳纳米管(MWCNTs)进行改性,采用红外光谱、热重分析手段对改性MWCNTs进行表征;将改性MWCNTs应用到膨胀型防火涂料体系中,研究了其对防火涂料性能的影响.结果表明:在适合的条件下两亲性聚合物可以被引入到多壁碳纳米管表面,改性后的MWCNTs在醋酸丁酯和水中具有良好的溶解性;合适含量的改性MWCNTs可以提高防火涂料受火后的炭化层强度和膨胀倍率,降低背温升高速率,增强涂层的抗开裂性能.     

Polyelectrolyte functionalized carbon nanotubes as a support for noble metal electrocatalysts and their activity for methanol oxidation

A highly effective polyelectrolyte functionalization of multi-walled carbon nanotubes (MWCNTs) by poly(diallyldimethylammonium chloride) (PDDA-MWCNTs) was employed for low temperature fuel cell applications. PDDA-MWCNTs were employed as support materials for the in?situ deposition and formation of platinum nanoparticles, via the self-assembly between the negative Pt precursor and positively charged functional groups of PDDA-functionalized MWCNTs. The effect of the functionalization on the deposition and distribution of Pt nanoparticles was investigated in detail. Compared with MWCNTs functionalized by conventional acid-oxidation treatment (AO-MWCNTs), the PDDA-functionalized MWCNTs cause no structural damage on MWCNTs and provide high density and homogeneous surface functional groups for the anchoring Pt nanoparticles. Pt nanoparticles with an average particle size of 1.8 ± 0.4?nm and loading as high as 60?wt% were realized on PDDA-MWCNTs supports. The Pt/PDDA-MWCNTs electrocatalysts show significantly higher electrochemically active surface area and higher electro-catalytic activity for methanol oxidation than that of Pt/AO-MWCNTs and E-TEK Pt/C electrocatalysts.     

Surface modification of multi-walled carbon nanotubes using 3-aminopropyltriethoxysilane

Multi-walled carbon nanotubes (MWCNTs) were functionalized via oxidation with a mixture of concentrated sulfuric acid and nitric acid. Thus functionalized nanotubes (f-MWCNTs) were silanized using a coupling agent, 3-Aminopropyltriethoxysilane (3-APTES). The f-MWCNTs and the reaction product of f-MWCNTs and 3-APTES (APTES–MWCNTs) were characterized by Fourier Transform Infrared Spectroscopy, Energy Dispersion Spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. The results indicate the attachment of silane molecules on the surface of the functionalized MWCNTs. This silanization method allows for the improvement of the chemical compatibility of MWCNTs with specific polymers for application in nanotube-based polymer matrix composites.     

Incorporation of liquid-like multiwalled carbon nanotubes into an epoxy matrix by solvent-free processing

Covalent attachment of 2,2'-(ethylenedioxy)-diethylamine to multiwalled carbon nanotubes (MWCNTs) produced amino-functionalized MWCNTs which behaved like liquids at ambient temperature. These liquid-like MWCNTs (l-MWCNTs) could be homogeneously dispersed and chemically embedded in an epoxy matrix by solvent-free processing. In contrast, solid MWCNTs (s-MWCNTs) functionalized by 1,8-diaminooctane were poorly dispersed in epoxy although they possess chemical structures and functionalization comparable to l-MWCNTs. An epoxy composite filled with pristine MWCNTs (p-MWCNTs) was also fabricated in the absence of a solvent at the same loading for comparison. The molecular level coupling of l-MWCNTs and epoxy provided significant improvements in overall mechanical properties relative to those composites containing p-MWCNTs and s-MWCNTs. The Young's modulus, storage modulus, tensile strength, failure strain and toughness of neat epoxy were increased by 28.4, 23.8, 22.9, 24.1 and 66.1%, respectively, by adding 0.5?wt% of l-MWCNTs. Thus, functionalized carbon nanotubes in liquid form contributed to better dispersion and superior interfacial bonding with the epoxy matrix, thereby facilitating greater mechanical reinforcement efficiency.