Functionalization of textiles with multi-walled carbon nanotubes by a novel dyeing-like process

Multi-walled carbon nanotubes (MWCNTs) were functionalized with oxygen-containing surface groups and subsequently incorporated in cotton and polyester fabrics by a process that mimics the traditional industrial dyeing process. The washing fastness, hydrophobicity and flame retardancy of the functional textiles were evaluated. The MWCNTs surface chemistry was modified by three different routes: (i) liquid phase oxidation with nitric acid, in order to introduce acidic oxygen-containing groups, (ii) thermal treatment of the sample oxidized in (i), in order to remove the carboxylic acid functionalities and (iii) gas phase oxidation with 5% oxygen in nitrogen to incorporate basic and neutral groups. All samples were characterized by temperature programmed desorption, pH at the point of zero charge and N₂ adsorption–desorption isotherms at −196 °C. The effect of the MWCNTs acidity/basicity and of the type of substrate in the nanomaterials incorporation efficiencies and in the performance of the final textile materials was assessed. The scanning electron microscopy images and the whiteness degree values of the functional textiles before and after washing indicated that the incorporation efficiency was higher for the textiles containing the most acidic MWCNTs, especially for the polyester textiles. The immobilization of the less acidic MWCNTs in polyester imparted hydrophobic properties to the fabrics surface; in particular, the polyester samples functionalized with unmodified and O₂-oxidized MWCNTs presented an almost superhydrophobic behaviour. In the case of the cotton-based samples, a hydrophobic behaviour was not achieved. Finally, the flame-retardant properties of both substrates improved upon the MWCNTs immobilization.     

含咔唑基2,2':6',2"-三吡啶衍生物的合成及其光学性质研究

设计合成了含咔唑基团的2,2':6',2"-三吡啶衍生物W1～W3,运用核磁共振氢谱,核磁共振碳谱对目标化合物进行了表征;研究了W1～w3分子的单光子荧光和双光子荧光光谱,并在密度泛函理论水平上,利用少态模型对W1～w3分子进行初步理论研究,理论计算结果与实验结果得到较好的吻合,为寻找新型双光子材料进行了有益的探索.     

Note on the dispersion in perfluoropolyether lubricants of multi-walled carbon nanotubes functionalized with (tridecafluoro-1,1 ,2,2-tetrahydrooctyl)trichlorosilane

Multi-walled carbon nanotubes functionalized with F3C-(CF2)5-(CH2)2-SiCl3, a molecule bearing a fluorinated terminal group is found to favor the carbon nanotubes dispersion in three perfluoropolyether fluids (Galden SV70, Fomblin Y25 and Fomblin YR1800). The stability of the suspension appears to be related to the perfluoropolyether viscosity. With respect to time, Fomblin YR1800, the more viscous fluid, leads to the most stable solutions, followed in order by Fomblin Y25 and Galden SV70. In general the smallest particles stay in suspensions. Stability extending over more than one year is observed in the case of Fomblin YR1800.     

Preparation, characterization, and electrochromic properties of novel Co(II)-bis-2,2’:6’,2”-terpyridine metallo-supramolecular polymers

A rich variety of novel ditopic bis-terpyridines, by symmetric and unsymmetric introduction of functional groups in the pyridine rings, as well as tuning the spacers for bridging the two terpyridine moieties, is described. These bis-terpyridines are useful ligands for developing new metallo-supramolecular materials with novel functions, as well as for investigating the structure-property relationships. In order to investigate the structural factors of bis-terpyridine based metallo-supramolecular materials, such as the functional groups in the ring periphery of the ligands and the spacers between the two terpyridine coordination components, several different types of Co^II-bis-terpyridine supramolecular polymers were prepared from various bis-terpyridine functional modules and Co(OAc)₂. The absorption and the electrochemical behavior of these new supramolecular polymers were studied by UV/Vis spectroscopy and differential pulse voltammetry (DPV), respectively. The results showed that the introduction of electron donating groups at the pyridine ring affects remarkably the charge transfer and electrochemical properties of the coordination polymers. In addition, the electrochromic properties of the coordination polymers were also studied. Significant color change and high reversibility were observed from these polymers.     

Functionalization of single- and multi-walled carbon nanotubes with cationic amphiphiles for plasmid DNA complexation and transfection

The possibility of delivering DNA efficiently to cells represents a crucial issue for the treatment of both genetic and acquired diseases. However, even although the efficiency of non-viral transfection systems has improved in the last decade, none have yet proven to be sufficiently effective in vivo. We report herein our results on the functionalization of single-walled carbon nanotubes (SWNT) and multi-walled carbon nanotubes (MWNT) by two cationic amphiphiles (lipid RPR120535 and pyrenyl polyamine), their use for the complexation of plasmid DNA, and their efficiency in transfecting cells in vitro. The experiments have shown that the efficiency of transfection is higher when using SWNT instead of MWNT, and that transfection efficiency is similar or slightly higher when using nanoplexes (SWNT/lipid RPR120535/DNA) instead of lipoplexes (lipid RPR120535/DNA) and several orders of magnitude higher than that of naked DNA. This study therefore shows both that the transfection is better when using SWNTs and that it is dependent on the nature of the amphiphilic molecules adsorbed on the nanotubes.      

Evolution of agglomerate structure of carbon nanotubes in multi-walled carbon nanotubes/polymer composite melt: A rheo-electrical study

Agglomerate structure of nano-fillers in polymer composite definitely plays a key role in the functionalization of nanocomposite. As nano-fillers are prone to agglomerating, the agglomerate structure is unstable and will experience a remarkable evolution in the melt state of the composite. In this work, the influence of melt annealing on the microstructure of multi-walled carbon nanotubes/poly(vinylidene fluoride) composites has been investigated by a combination of rheological behavior and electrical properties. The simultaneous measurement, which is combined with investigations of rheological behavior and resistance, reveals that the evolution of microstructures during melt annealing shows a significant effect on both the viscoelasticity and electrical conductivity of composites. Besides, a watershed behavior is found for the evolution of microstructure in samples with the content of MWCNTs higher and lower than the electrical percolation threshold (φ_C) during annealing. Particularly, samples with the content of MWCNTs above φ_C exhibit a noteworthy increment in storage modulus and a dramatic decrease in resistance, while those with the content of MWCNTs below φ_C display a quick decrease in electrical conductivity and only a slight increment in storage modulus.     

Evolution of agglomerate structure of carbon nanotubes in multi-walled carbon nanotubes/polymer composite melt: A rheo-electrical study

Agglomerate structure of nano-fillers in polymer composite definitely plays a key role in the functionalization of nanocomposite. As nano-fillers are prone to agglomerating, the agglomerate structure is unstable and will experience a remarkable evolution in the melt state of the composite. In this work, the influence of melt annealing on the microstructure of multi-walled carbon nanotubes/poly(vinylidene fluoride) composites has been investigated by a combination of rheological behavior and electrical properties. The simultaneous measurement, which is combined with investigations of rheological behavior and resistance, reveals that the evolution of microstructures during melt annealing shows a significant effect on both the viscoelasticity and electrical conductivity of composites. Besides, a watershed behavior is found for the evolution of microstructure in samples with the content of MWCNTs higher and lower than the electrical percolation threshold (φ_C) during annealing. Particularly, samples with the content of MWCNTs above φ_C exhibit a noteworthy increment in storage modulus and a dramatic decrease in resistance, while those with the content of MWCNTs below φ_C display a quick decrease in electrical conductivity and only a slight increment in storage modulus.     

Photoactive Zn(II)Porphyrin–multi-walled carbon nanotubes nanohybrids through covalent β-linkages

Donor–acceptor nanohybrids by a covalent linkage between the β-position of a Zn(II)Porphyrin and multi-walled carbon nanotubes are reported for the first time, in a closer analogy to the natural light harvesting systems, which are based on β-substituted porphyrinoid structures, the chlorophylls. An unique and direct connection was established through the immobilization of the Zn(II)(β-NH₂-tetraphenylporphyrin), using diazonium chemistry, in order to afford i) a short and conjugated linkage between the two aromatic systems and ii) an amide bond resulting from a three-step functionalization synthesis. Electronic and steady-state fluorescence spectroscopies confirmed high photoinduced electron communication through the β-linkage when compared to analogous meso-phenyl linkers, stating its positive effect. The procedure involving the amide linkage allowed higher chromophore loadings; however, the direct conjugated bond showed improved photoinduced activity and a different emission pattern that can be associated with intense communication within the expanded π-system MWCNT–metalloporphyrin.     

Adsorption of Ni(II) on oxidized multi-walled carbon nanotubes: Effect of contact time,pH, foreign ions and PAA

The adsorption of Ni(II) on oxidized multi-walled carbon nanotubes (MWCNTs) as a function of contact time, pH and foreign ions in the absence and presence of polyacrylic acid (PAA) was studied using batch technique. The results indicated that adsorption of Ni(II) on oxidized MWCNTs increased from zero to ∼99% at pH 2–9, and then maintained the high level with increasing pH. Kinetic data showed that the adsorption process achieved equilibrium within 2 h and experimental data were fitted well by the pseudo-second-order equation. A positive effect of PAA on Ni(II) adsorption was found at pH < 8, whereas a negative effect was observed at pH > 8. The effect of addition sequences of PAA/Ni(II) on the adsorption of Ni(II) to PAA–MWCNT hybrids were also studied. The results indicated that the adsorption of Ni(II) was influenced by addition sequences obviously. The adsorption of Ni(II) on oxidized MWCNTs may be mainly attributed to surface complexation and ion exchange. Oxidized MWCNTs are suitable material in the solidification and pre-concentration of Ni(II) from aqueous solutions.     

Synthesis and characterization of multi-walled carbon nanotubes functionalized with hyperbranched poly(urea-urethane)

Two types of hyperbranched poly(urea-urethane)-functionalized multi-walled carbon nanotubes (GHPU) have been synthesized in the presence of bis- and tris-hydroxy terminated carbon nanotubes (MWNT-OH). For comparison of the grafting efficiency on carbon nanotubes, pure hyper-branched poly(urea-urethane)s (HPUs) were also synthesized to prepare pristine carbon nanotubes-reinforced nanocomposites (HPNTs). Better MWNT dispersion in the polymer matrix was obtained for GHPU than for HPNT, and the effect was superior in the case of highly branched GHPU from tris-hydroxy-functionalized MWNTs, compared to GHPU from bis-hydroxy-functionalized MWNTs. TEM measurements for GHPUs clearly showed hyperbranched polymer-wrapped MWNT structures. Crystallization of hyperbranched polymers in GHPU was more developed than that of the HPNT nanocomposites, although MWNT-induced crystallization was observed for both the GHPU and HPNT samples. The hyperbranched polymer-grafting effect on MWNTs resulted in greater enhancement of the mechanical properties of GHPU at the same nanotube loading, compared to the case of HPNT nanocomposites. However, a too highly branched structure was found to lower the crystallization and mechanical properties of both the GHPUs and HPNTs.     

Synthesis of polyimide from 5,5'-bis(bromomethyl)-2,2':6',2'-terpyridine and investigation of the polymer sorption behavior towards some metal ions

The synthesis of a terpyridine-based polyimide sorbent for solid-phase extraction (SPE) of some metal ions is described. For this purpose, 5,5'-bis(bromomethyl)-2,2':6',2'-terpyridine was polymerized with the corresponding diimide derivatives of dianhyrides to give polyimides utilizing terpyridine unit in the main chain. This polymer was used for its extraction capabilities for Pb(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II), at different pH. Under competitive conditions and at pH<0.6, the selectivity order was Pb approximately Cd approximately Zn. Enhanced selectivity was observed at pH 3.5, the order was Cu>Ni>Zn approximately Cd approximately Pb. Quantitative recoveries>97% were observed for all metals in case loading was stopped before reaching the point of breakthrough. As the synthesized polyimides are insoluble in water, solid-liquid extractions have been carried out and the resins sorption for mixture of basic and/or precious metals have been studied under various experimental conditions (reaction time and hydrochloric acid concentration).     

Mechanical properties of porous Al2O3 composite with surface modified multi-walled carbon nanotubes (MWCNTs)

Multi-walled carbon nanotubes (MWCNTs) have been reinforced in alumina (Al2O3) matrix to overcome the inherent brittleness of the Al2O3 matrix. In this work, MWCNTs were treated by acid to provide hydrophilicity to hydrophobic MWCNTs, inducing the homogeneous dispersion of MWCNTs in an aqueous solution. Aluminum hydroxide (Al(OH)3) as a Al2O3 precursor was added in the solution with the modified MWCNTs, and then this mixture solution was filtered at room temperature. The prepared powders were calcinated at 800-1000 degrees C to reduce the gas pocket in the matrix by decomposition of Al(OH)3. Then the calcinated powders were formed, and heat-treated. The porous MWCNTs-Al2O3 composites show higher mechanical properties in flexure strength and hardness than the porous Al2O3 without the reinforcement phase, which is attributed to the high mechanical properties of MWCNTs. However, higher MWCNTs contents in the composites decrease the mechanical properties due to the aggregation of MWCNTs in the composites. Therefore, control of the MWCNTs content and its dispersibility in the matrix are key factors to be considered for the fabrication of the porous MWCNT-Al2O3 composites.     

Electrochemiluminescent detection based on solid-phase extraction at tris(2,2'-bipyridyl)ruthenium(II)-modified ceramic carbon electrode

A sensitive electrochemiluminescent detection scheme by solid-phase extraction at Ru(bpy)3(2+)-modified ceramic carbon electrodes (CCEs) was developed. The as-prepared Ru(bpy)3(2+)-modified CCEs show much better long-term stability than other Nafion-based Ru(bpy)3(2+)-modified electrodes and enjoy the inherent advantages of CCEs. The log-log calibration plot for dioxopromethazine is linear from 1.0 x 10(-9) to 1.0 x 10(-4) mol L(-1) using the new detection scheme. The detection limit is 6.6 x 10(-10) mol L(-1) at a signal-to-noise ratio of 3. The new scheme improves the sensitivity by approximately 3 orders of magnitude, which is the most sensitive Ru(bpy)3(2+) ECL method. The scheme allows the detection of dioxopromethazine in a urine sample within 3 min. Since Ru(bpy)3(2+) ECL is a powerful technique for determination of numerous amine-containing substances, the new detection scheme holds great promise in measurement of free concentrations, investigation of protein-drug interactions and DNA-drug interactions, pharmaceutical analysis, and so on.     

Removal and recovery of lead (II) ions from contaminated licorice extracts using oxidized multi-walled carbon nanotubes

A column with oxidized multi-walled carbon nanotubes (MWNTs) has been studied as a sorbent for removing and accumulating lead (II) from contaminated Licorice extracts. Under optimized situation, the adsorption capacity of lead (II) on oxidized MWNTs was 17 mg g(-1) at pH 7.0, and the lead (II) was eluted with 10 ml of 1% hydrochloric acid. Additionally, the effects of adsorptive parameters, including pH of the solution, sample volume, flow rates of the sample, matrix ions, and eluent type were investigated for optimization of the presented procedure. A fluorescence spectrophotometer was employed to determine the contents of lead (II). High-performance liquid chromatography (HPLC) was developed for the quantitative determination of main constituents of Licorice extracts. Oxidized MWNT cartridges were used to remove lead ions from contaminated Licorice extracts, high adsorption capacity, adsorption reversibility of lead (II), and low loss of major constituents. The results suggested that the oxidized MWNT column has the potential to remove heavy metal ions from herbal extracts.     

Functionalization of conducting polymer with novel Co(II) complex: Electroanalysis of ascorbic acid

We report for the first time the functionalization of a conducting polymer with a metal complex in order to develop a new type of catalytic material exhibiting better electronic communication through their delocalized π electrons. The Co(II) complex having hydroxyl group as functional moiety is chemically coupled with carboxyl group of polyanthranilic acid which itself is a self doped conducting polymer. The covalent linkage between Co(II) and –OH group is confirmed using UV–vis, FT-IR and NMR spectroscopic techniques. The Co(II) complex functionalized polymer does exhibit excellent redox behavior and stability with mixed properties of Co(II) complex and π-conjugated polymer. The material possesses potential benefits in sensors/biosensor applications and it is demonstrated for the electroanalysis of ascorbic acid at a level of nano molar concentration.     

The preparation of highly water-soluble multi-walled carbon nanotubes by irreversible noncovalent functionalization with a pyrene-carrying polymer

Multi-walled carbon nanotubes (MWNTs) have been solubilized in water via a noncovalent method of exfoliation and centrifugation cycles with the assistance of hydrolyzed poly(styrene-co-maleic anhydride) carrying pyrene (HPSMAP). After the obtained solution was micro-filtered and dried, a water-soluble complex of HPSMAP-MWNTs was obtained. The solubility of HPSMAP-MWNTs was measured to be 46.2?mg?ml(-1) with a net MWNT concentration of 7.4?mg?ml(-1) in water. Thermal gravimetric analyses showed that there was a large amount of polymer remaining on the surface of MWNTs irreversibly after thoroughly removing the free polymer. Other characterizations using transmission electron microscopy, Fourier transform infrared (FTIR) spectroscopy, fluorescence spectra, and fluorescence decay were conducted.     

Functionalization of nitrogen-doped carbon nanotubes with gallium to form Ga-CN(x)-multi-wall carbon nanotube hybrid materials

In an effort to combine group III-V semiconductors with carbon nanotubes, a simple solution-based technique for gallium functionalization of nitrogen-doped multi-wall carbon nanotubes has been developed. With an aqueous solution of a gallium salt (GaI(3)), it was possible to form covalent bonds between the Ga(3+) ion and the nitrogen atoms of the doped carbon nanotubes to form a gallium nitride-carbon nanotube hybrid at room temperature. This functionalization was evaluated by x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy.     

多壁碳纳米管的处理及其在芳纶1313中的分散

为了改善多壁碳纳米管(MWNTS)在溶剂N,N-二甲基乙酰胺(DMAc)中的分散性,提高MWNTs与芳纶1313(PMIA)基体界面的结合性能,用混酸对MWNTs进行了处理,用FT-IR对处理前后的MWNTs进行了表征,发现处理后的MWNTs表面接上了羧基.通过溶液共混的方法制得了PMIA/MWNTs纳米复合薄膜,并用SEM和TEM对其进行了表征,发现处理后的MWNTs在PMIA基体中的分散更为均匀.     

Dispersion of multi-walled carbon nanotubes in biodegradable poly(butylene succinate) matrix

This communication describes the preparation, characterization and properties of biodegradable poly(butylene succinate) (PBS)/multi-walled carbon nanotubes (MWCNTs) nanocomposite. Nanocomposite was prepared by melt-blending in a batch mixer and the amount of MWCNTs loading was 3 wt%. State of dispersion-distribution of the MWCNTs in the PBS matrix was examined by scanning and transmission electron microscopic observations that revealed homogeneous distribution of stacked MWCNTs in PBS matrix. The investigation of the thermomechanical behavior was performed by dynamic mechanical thermal analysis. Results demonstrated substantial enhancement in the mechanical properties of PBS, for example, at room temperature, storage flexural modulus increased from 0.64 GPa for pure PBS to 1.2 GPa for the nanocomposite, an increase of about 88% in the value of the elastic modulus. The tensile modulus and thermal stability of PBS were moderately improved after nanocomposite preparation with 3 wt% of MWCNTs, while electrical conductivity of neat PBS dramatically increased after nanocomposite formation. For example, the in plane conductivity increased from 5.8 x 10(-9) S/cm for neat PBS to 4.4 x 10(-3) for nanocomposite, an increase of 10(6) fold in value of the electrical conductivity.