• Advances in nano research
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• 제11권6호
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• pp.667-678
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• 2021

Multiwalled carbon nanotubes (MWCNTs) were first oxidized (O-CNTs) to introduce carboxylic group and then further functionalized (F-CNTs) with m-phenylenediamine, which was confirmed by FTIR and SEM. It was used as an effective adsorbent for the adsorptive removal of diclofenac drug from water. Under optimum conditions of pH 6, stirring speed 600 rpm, the maximum adsorption capacity obtained was 532 mg g^-1 which is superior to the values reported in literature. The adsorption was quite rapid as 25 mg L^-1 drug solution was adsorbed in only 3 minutes of contact time with 10 mg of adsorbent dose. The adsorption kinetics and isotherms were studied using various models to evaluate the adsorption process. The results showed that the data best fit in kinetics pseudo-second order and Langmuir isotherm model. Furthermore, the oxidized and functionalized MWCNTs were applied on gram-negative Escherichia coli and gram-positive Staphylococcus aureus using agar disc diffusion assay to validate their anti-microbial activity. Results were unique as both oxidized and functionalized MWCNTs were equally active against both E. coli and S. aureus. The newly synthesized F-CNTs have great potential in water treatment, with their dual action of removing drug and pathogens from water, makes it potential applicant to save environment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.126-131
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• 2004

Chemically modified multiwalled carbon nanotubes with acids were incorporated into a epoxy matrix by in situ polymerization process, to improve the transfer of mechanical load through chemical bonds, which were demonstrated by infrared spectroscopy. And the mechanical properties of epoxy/carbon nanotube composites were measured to investigate the role of carbon nanotubes. The epoxy/carbon nanotube composites shows higher tensile strength and wear resistance than existing epoxy, with 1 or 2 wt. % addition of functionalized carbon nanotubes. The tensile strength with 7 wt. % carbon nanotibes is increased by a 28% and the wear resistance in exceptionally increased by an outstanding 100 times.

• Bulletin of the Korean Chemical Society
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• 제34권11호
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• pp.3391-3398
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• 2013

The carboxylated multiwall carbon nanotubes (MWCNT-COOH) and functionalized with isatin derivative (MWCNT-isatin) have been used as efficient adsorbents for the removal of lead (Pb) from aqueous solutions. The influence of variables including pH, concentration of the lead, amount of adsorbents and contact time was investigated by the batch method. The adsorption of the lead ions from aqueous solution by modified MWCNTs was studied kinetically using different kinetic models. The kinetic data were fitted with pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The sorption process with MWCNT-COOH and MWCNT-isatin was well described by pseudo-second-order and pseudo-first-order kinetics, respectively which it was agreed well with the experimental data. Also, it involved the particle-diffusion mechanism. The values of regression coefficient of various adsorption isotherm models like Langmuir, Freundlich and Tempkin to obtain the characteristic parameters of each model have been carried out. The Langmuir isotherm was found to best represent the measured sorption data for both adsorbent.

• 폴리머
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• 제31권5호
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• pp.436-441
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• 2007

In this work, the multiwalled carbon nanotubes(MWNTs) were functionalized with sodium dodecylbenzene sulfonate(SDBS) and then MWNTs/Lyocell composite fibers were prepared. The properties of MWNTs, the functionlization on the surface of MWNTs and their dispersion in the cellulose matrix were characterized by TEM, SEM, WAXD and FT-IR. The results showed that SDBS has been coated successfully onto the surface of the MWNTs by functionlization. This can improve effectively the dispersion uniformity of MWNTs in NMMO aqueous solution and is helpful to prepare a spinnable spinning dope. Moreover, the resultant MWNTs/Lyocell composite fibers still have cellulose II crystal structure, and their tensile strength and initial modulus increased with the increasing draw ratio and reached the optimal value with adding 1 wt% MWNTs. The thermal stability of the composite fiber was also improved by the addition of the MWNTs.

• Carbon letters
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• 제11권2호
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• pp.96-101
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• 2010

Dispersion of the functionalized multiwalled nanotubes (MWNT) in the polyurethane (PU) matrix and DC conductivity of the MWNT/PU composites are investigated with the oxidation conditions, the kind of surfactants and their content. First, the most optimal surfactant type and its critical micelle concentration in the MWNT suspension are determined as a cationic surfactant, benzalkonium chloride (BKC) of 0.6 wt.% to the MWNT content from DEA and FESEM results. All the MWNT oxidized under several conditions are negatively charged and functionalized with carboxylic group, whereas the degree of damage is different from oxidation conditions. In addition, each MWNT/PU composite derived from several oxidation conditions shows different DC conductivity at a characteristic MWNT content. It is found that in order to enhance DC conductivity of the polymeric composites containing the oxidized MWNT the better dispersion of MWNT should be obtained by effective functionalities and surfactant adsorption with preserving the intrinsic geometry of pristine MWNT.

• Macromolecular Research
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• 제15권6호
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• pp.498-505
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• 2007

This study demonstrated the in-situ functionalization with polymers of multi-walled carbon nanotubes (MWNTs) via emulsion polymerization. Polystyrene-functionalized MWNTs were prepared in an aqueous solution containing styrene monomer, non-ionic surfactant and a cationic coupling agent ([2-(methacryloyloxy)ethyl]trime-thylammonium chloride (MATMAC)). This process produced an interesting morphology in which the MWNTs, consisting of bead-string shapes or MWNTs embedded in the beads, when polymer beads were sufficiently large, produced nanohybrid material. This morphology was attributed to the interaction between the cationic coupling agent and the nanotube surface which induced polymerization within the hemimicellar or hemicylindrical structures of surfactant micelles on the surface of the nanotubes. In a solution containing MATMAC alone without surfactant, carbon nanotubes (CNTs) were not well-dispersed, and in a solution containing only surfactant without MATMAC, polymeric beads were synthesized in isolation from CNTs and continued to exist separately. The incorporation of MATMAC and surfactant together enabled large amounts of CNTs (> 0.05 wt%) to be well-dispersed in water and very effectively encapsulated by polymer chains. This method could be applied to other well-dispersed CNT solutions containing amphiphilic molecules, regardless of the type (i.e., anionic, cationic or nonionic). In this way, the solubility and dispersion of nanotubes could be increased in a solvent or polymer matrix. By enhancing the interfacial adhesion, this method might also contribute to the improved dispersion of nanotubes in a polymer matrix and thus the creation of superior polymer nanocomposites.

• Macromolecular Research
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• 제17권12호
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• pp.987-994
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• 2009

Palladium nanoparticles having cubic silsesquioxanes (POSS) (Pd-POSS) were produced by the reaction of palladium (II) acetate and octa(3-aminopropyl)octasilsesquioxane octahydrochloride (POSS-${NH_3}^+$ in methanol at room temperature. Functionalized multiwalled carbon nanotubes (MWNT-COOH) were prepared by acid treatment of pristine MWNTs. The hybrid nanocomposites of Pd-POSS and MWNT-COOH (Pd-MWNT nanocomposites) were synthesized by self-assembly method via ionic interaction between positively charged Pd-POSS and negatively charged MWNT-$COO^-$. The spherical aggregates of Pd-POSS with a diameter of 40-60 urn were well attached to the surfaces of MWNT-COOH on Silicon wafer. The composition, structure, and surface morphology of Pd-MWNT nanocomposites were studied by UV-vis spectrophotometer, energy dispersive spectrum (EDX), scanning electron microscopy (SEM), and atomic force microscope (AFM).

• Composites Research
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• 제32권6호
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• pp.375-381
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• 2019

Multiwalled carbon nanotubes (MWCNTs) are covalently functionalized with isocyanates by directly reacting commercial hydroxyl functionalized MWCNTs with excess 4,4'-methylenebis (phenyl isocyanate) (MDI) and hexamethylene diiosocyanate (HDI). HDI-modified MWCNTs results in a higher surface isocyanate density than MDI-modified MWCNTs. Anionic ring-opening polymerization of ε-caprolactam is conducted using a sodium caprolactam initiator in combination with a di-functional hexamethylene-1,6-dicarbamoylcaprolactam activator in the presence of isocyanate functionalized MWCNTs. This polymerization proceeds in a highly efficient manner at relatively low reaction temperature (150℃) and short reaction times (10 min). During the polymerization, the isocyanate functionalized MWCNTs act not only as reinforcing fillers but also as second activators. Nanocomposites with HDI modified MWCNTs exhibit higher reinforcement and faster isothermal crystallization than MDI modified MWCNTs. The results show that PA6 chains grow more effectively from HDI modified MWCNT surface than from MDI modified MWCNT surface, resulting in stronger interaction between PA6 and MWCNTs.

• Transactions on Electrical and Electronic Materials
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• 제14권3호
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• pp.125-129
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• 2013

Composites of platinum and multiwalled carbon nanotubes (MWNTs) were prepared in various reduction conditions and characterized using cyclic voltammetry. The MWNTs were functionalized with carboxylic acid and/or hydroxyl groups in acidic solutions prior to the formation of MWNT-Pt composites. Platinum nanoparticles were deposited onto the chemically-oxidized MWNTs in 1-propanol and 1,3-propanediol. The reduction of Pt precursors in other solutions could induce differences in their morphologies in composite thin films. The morphologies of MWNTs with Pt deposited were dependent on the reduction solutions, and the electrocatalytic activities on alcohols changed accordingly. The electrochemical activities of the as-prepared MWNT-Pt thin films on common alcohols such as methanol and ethanol were investigated.

• Advances in nano research
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• 제5권3호
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• pp.245-251
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• 2017

Multiwalled carbon-nanotubes (MWCNT) and micro-structured carbon, such as biochar or activated carbon (AC), have been seen to significantly increase the growth indices of certain plant species such as maize (Zea mays L.). Seed imbibition is the stage where environmental factors that affect water transport across the seed coat barrier, make a large impact. This work explores the effect on water imbibition by maize seeds when the aqueous environment surrounding the seed is diluted by small concentrations (10 and 20 mg/l) of pristine MWCNT (p-MWCNT), carboxylate functionalized MWCNT (COO-MWCNT) and AC. The degree of sensitivity of the process to (i) large structural changes is seen by utilizing the nano (the MWCNT) and the micro (the AC) allotropic forms of carbon; (ii) to small changes in the purity and morphology of the p-MWCNT by utilizing 95% pure and 99% pure p-MWCNTs of slightly differing morphologies; and (iii) to MWCNT functionalization by using highly pure (97%) COO-MWCNT. Water imbibition was monitored over a 15 hour period by Near Infrared Thermography (NIRT) and also by seed weighing. Seed surface topography was seen by SEM imaging. Analysis of the NIRT images suggests rapid seed surface topological changes with the quantity of water imbibed. While further work is necessary to arrive at a conclusive answer, this work shows that the imbibition phase of the maize seed is sensitive to the presence of MWCNT even to small differences in the purity of the p-MWCNT and to small differences in the physicochemical properties of the medium caused by the hydrophilic COO-MWCNT.