Electro-generated nickel/carbon nanotube composites in ionic liquid

It is reported, for the first time, that compact nickel-multiwalled carbon nanotube (Ni/MWCNT) composites were successfully electrodeposited in choline chloride/urea based deep eutectic solvent (DES) on a copper substrate. Dispersion stability of MWCNTs is excellent in DES nickel chloride solution therefore electrodeposition of Ni/MWCNT composites was easily achieved. MWCNTs were uniformly distributed in the nickel matrix and gave different morphologies and high surface roughness to the coating. Coating with oxygen-functionalized MWCNTs exhibited higher stability and better corrosion resistance than the coating with pristine MWCNTs.     

Polyelectrolyte multilayer modified nanofiltration membranes for the recovery of ionic liquid from dilute aqueous solutions

The feasibility of nanofiltration membranes fabricated by static polyelectrolyte layer‐by‐layer deposition of poly(styrene sulfonate) and poly(allylamine hydrochloride) on poly(ether sulfone) ultrafiltration and alumina microfiltration membranes for the recovery of ionic liquid from low molecular weight sugar was investigated. The surface properties of these modified membranes were correlated with their performances. The selectivity for 1‐butyl‐3‐methylimidazolium chloride over cellobiose and glucose was found to be as high as 50.5/2.3 for modified alumina and 32.3/3.5 for modified poly(ether sulfone) membranes with optimized number of bilayers. The values for membrane permeance were 4.8 and 2.5 L m^?1 h² bar^?1, respectively. For low depositions, the separation mechanism was predominantly governed by size‐exclusion. For higher depositions, the enhanced negative zeta potential of the modified membranes suggested preferred dominating electrostatic interactions, resulting in high selectivity of ionic liquids over low molecular weight sugars. At very high depositions, the molecular weight cut‐off of the membrane becomes constricting for size‐exclusion effect. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134 , 45349.     

Mechanical properties of carbon nanotube paper in ionic liquid and aqueous electrolytes

Porous mats of carbon nanotubes, referred to as bucky paper, are becoming a viable engineering material, especially as electrodes in numerous types of electrochemical cells. The tensile strength of bucky paper was measured in the dry atmospheric condition, and the wet conditions of both water and 1-butyl-3-methyl-imidazolium tetrafluoroborate, an ionic liquid. The two different liquids have a significant impact on the mechanical properties of bucky paper, even when they are not known for readily wetting the nanotubes. It is shown that capillary forces contribute to the mechanical properties of bucky paper. It is also shown that there is a strong interaction between ionic liquid and carbon nanotubes.     

Single-walled carbon nanotube growth from liquid gallium and indium

We present the first demonstration of single-walled carbon nanotube growth from liquid gallium and indium catalysts. The nanotubes were grown via thermal chemical vapor deposition from 1 to 3 nm films of gallium and indium, which dissociate into liquid droplets on silicon substrates at high temperatures. The nanotubes were characterized by Raman spectroscopy and atomic force microscopy and are found to have diameters between 1 and 2 nm.     

Self-assembly of carbon nanotube films from room temperature ionic liquids

A novel method for the assembly of thin, uniform transparent and conductive films of single-walled carbon nanotubes (SWCNTs) on glass substrates is described. This process involves the initial transfer of a temporary suspension of SWCNTs in room temperature ionic liquid to the surface of water and the subsequent transfer of the SWCNT film onto a glass substrate. The average sheet resistance of the films was determined by four point probe measurements to be 1.52 and 4.13 kΩ/sq, with an average optical transparency of 50% and 63%, respectively.     

Fast-moving bimorph actuator based on electrochemically treated millimeter-long carbon nanotube electrodes and ionic liquid gel

The development is described of an electromechanical bimorph actuator composed of ionic liquid gel sandwiched by electrochemically treated millimeter-long single-walled carbon nanotubes (SG-SWNT). Electrochemical doping of the SG-SWNT and electrochemical polymerization of polypyrrole on the surface of the SG-SWNT improved the performance of a previously reported actuator using non-treated SG-SWNTs. The conductivity of the SG-SWNT sheets treated at the anodic potential (doped) was found to be three times larger than that of the original film. The generated strain of the actuator prepared from the doped SG-SWNT sheets was increased compared to that prepared from non-doped sample. Moreover, the generated strain of the actuator from the doped SG-SWNT sheets swelled with ionic liquid (IL) was increased to twice that without ILs. The electropolymerization of pyrrole on the surface of the SG-SWNT sheet was carried out. The conductivity of the SG-SWNT was seven times larger after the electropolymerization. The generated strain of the SG-SWNT actuator prepared from the SG-SWNT sheets with electropolymerization was twice as large as that without the electropolymerization at low frequency. At higher frequency, both actuators provide almost the same performance. Both actuators exhibit mechanical resonance at about 100 Hz.     

Wet spun fibers from solutions of cellulose in an ionic liquid with suspended carbon nanoparticles

Wet spun fibers from solutions of dissolving pulp in 1‐ethyl‐3‐methylimidazolium acetate (EmimAc) with up to 50 wt % (based on cellulose) suspended carbon black and graphene nanoplatelets particles were studied. Carbon fillers were dispersed by simple shearing in a Couette type mixer and the resulting spin dope was extruded into a hot water coagulation bath from a single hole spinneret. Microstructure, mechanical properties, and electrical conductivity were assessed as a function of filler loading and discussed in comparison to melt spun fibers with similar fillers. The coagulation process and subsequent drying of wet spun fibers was found to produce a significant microporosity, more so the higher the filler loading. The electrical percolation threshold was quite high in the wet spun fibers and relatively modest values of conductivity were obtained with regard to the high filler loadings. Carbon black was found to be superior to graphene nanoplatelets. This was related to flow‐induced orientation effects. The mechanical properties of the carbon‐filled fibers were found to be similar or lower compared to the pure cellulose fibers because of low interfacial interactions and formation of microporosity. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41417.     

离子液体中制备碳纳米管复合材料的研究

与传统的溶剂相比,离子液体作为一种新型的绿色环保溶剂及优良电解质,在碳纳米管复合材料制备中得到了广泛的应用.对近年来利用离子液体合成出的碳纳米管/金属复合材料、碳纳米管/纤维素复合材料、碳纳米管/聚合物复合材料,以及在高分子离子液体、离子液凝胶中制备的碳纳米管复合材料进行了综述,介绍它们的优势及特点.对今后离子液体在碳...     

氨丙基离子液体水溶液CO2吸收特性及计算模型

氨丙基功能型离子液体对CO₂具有良好的选择吸收特性,以[APMim]Br离子液体水溶液体系为例,在有效吸收(水含量大于55%)区间,水含量对CO₂的化学吸收和物理吸收都具有显著影响。依据[APMim]Br水溶液在278.15~348.15 K,0.1~4.5 MPa,水质量分数为55.90%、64.50%、76.80%和85.80%范围的CO₂吸收特性数据,对溶液体系的化学吸收和物理吸收模型进行分析研究,获得两种吸收机理的数学表达,并对实验数据进行回归分析,得到能够正确反映化学吸收和物理吸收的计算模型。结果表明,低压下化学吸收占主导作用,随水含量增大,溶液体系对CO₂吸收能力成倍增加,而且产生的物理吸收效应远大于离子液体本身的化学吸收能力。水的质量分数在0.65~0.85区间,[APMim]Br水溶液在相当大的温度和压力范围内具有优良的CO₂吸放气特性,显示出良好的工程应用前景。     

Anisotropic carbon nanotube papers fabricated from multiwalled carbon nanotube webs

We fabricated large-scale anisotropic carbon nanotube (CNT) paper sheets by stacking long-lasting multiwalled CNT (MWCNT) webs without using binder materials. The MWCNTs are highly aligned in the webs and they retain their alignment in the fabricated paper. Although MWCNTs are just connected by van der Waals force, tensile strength is as strong as 75.6 MPa. In addition, resistivity and thermal conductivity is as good as 2.5 × 10⁻³ Ω cm and 70 W/m K, respectively. The present high anisotropy ratios of 7.3 in resistivity and of 8.1 in thermal conductivity are due to the high alignment of the ultra-long MWCNTs which have lengths of millimeters. High-speed web drawing with a draw speed of over 10 m/s enables very rapid fabrication. The material properties of CNT structures can be measured by conventional methods for macroscopic samples rather than methods designed for nanomaterials. CNT web technology will enable CNTs to be used in new applications.     

Pervaporation removal of water from ionic liquid solutions using Nafion membranes

We report a pervaporation process to remove water from a solution containing ionic liquid (IL) + solvent + water. Specifically, Nafion-based membranes were employed for the separation, and tributylmethylammonium dimethylphosphate and N-methyl-2-pyrrolidone (NMP) were the IL and solvent, respectively. Membrane swelling in contact with the IL–NMP–H₂O solution was accommodated by judicious use of gaskets and membrane supports. The pervaporation fluxes of water and NMP increased with temperature and flow rate of the permeate sweep gas. Among the membranes examined, a commercially available Nafion membrane (XL, Ion Power) provided the highest water (10 mg h^?1 cm^?2) and NMP (182 mg h^?1 cm^?2) fluxes. The results show that pervaporation separation is a technologically feasible method to decrease the water content of an IL–NMP–H₂O solution from 1 to 0.5 wt%.     

Electrochemical behavior of glassy carbon electrodes modified by multi-walled carbon nanotube/surfactant films in a buffer solution and an ionic liquid

The electrochemical behavior of glassy carbon (GC) electrodes coated with multi-walled carbon nanotube (MWCNT)/surfactant films was studied in an ionic liquid and a phosphate buffer solution (pH = 6.86), using cyclic voltammetry. The dispersion of MWCNTs in different media was investigated by scanning and transmission electron microscopy. Cast films of MWCNT/zwitterionic dodecyldimethylamine oxide on a GC electrode show a typical redox couple in phosphate buffer solution, which is better than that of MWCNT/anionic sodium dodecyl sulfate and cationic alkyltrimethylammonium bromide. However in the ionic liquid, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]), the GC electrode modified by MWCNT/cationic surfactant films shows a well-defined irreversible reduction of MWCNTs. The cyclic voltammograms clearly show that the surfactant hydrophilic group plays an important role in the electrochemical behavior of the MWCNTs. The electrolytes also have an important effect. In an ionic liquid, the strong binding of the ionic liquid cations with the MWCNTs may change the structure of the modified films and lead to changes of electrochemical behavior.     

Development of microreactors made of vertically aligned carbon nanotube films

Microreactors consisting of multiwalled carbon nanotube (CNT) microchannels have been developed. Vertically aligned CNT films with negative pattern shapes of microchannels are grown on silicon oxide films, providing CNT microchannels. Polymethyl methacrylate plates are placed on the CNT microchannels for the flow experiments. Since CNTs are hydrophobic and the silicon oxide film is hydrophilic, fluids can flow in the silicon oxide regions in the CNT microreactors. Fermat’s spiral and Y-junction type multiwalled CNT microreactors were synthesized.     

Improving the actuating response of carbon nanotube/ionic liquid composites by the addition of conductive nanoparticles

Polyaniline (PANI) or carbon black (CB) was used as a conductive additive in porous electrodes of a dry-type carbon nanotube (CNT)-polymer actuator to improve the actuation properties. We estimated the strain from the bending motion of the actuator in the frequency range of 200–0.005 Hz. The generated stress was calculated from the Young’s modulus of the electrode film and the maximum strain. Eight different types of electrode films were prepared by changing the mixed amount of PANI or CB into the CNT electrode film. When a same amount of PANI (50 mg) against CNT (50 mg) was added to the CNT electrode (in the case of CNT/PANI(50/50)), the strain of CNT/PANI(50/50) was increased to be almost three times larger than that of CNT(50) (without any additives). As a result, CNT/PANI(50/50) showed more than five times the generated stress compared to CNT(50). Using 40 mg of CB as an additive, CNT/CB(50/40) showed a more than four times larger stress compared to CNT(50). The electrochemical properties such as conductivity and capacitance were also investigated and discussed. An asymmetrical three-layered actuator element was fabricated to investigate the actuation mechanism. The results imply that the anode contracts and the cathode expands.     

Conducting polymer/carbon nanotube composite films made by in situ electropolymerization using an ionic surfactant as the supporting electrolyte

We have demonstrated a simple and general strategy, namely in situ electropolymerization by using an ionic surfactant as the electrolyte, for alignment of disordered CNTs within conducting polymer/carbon nanotube composite films. The single- or multi-walled CNTs were first dispersed in an aqueous solution containing SDS (sodium dodecyl sulfate), then electroactive monomer pyrrole or N-methylpyrrole was added into the above mixture, finally electrochemical reaction was proceeded at the surface of the Au electrode and correspondingly a series of conducting polymer/carbon nanotube composite films with the orientation of carbon nanotubes were obtained.     

Comparative investigation on electrochemical behavior of hydroquinone at carbon ionic liquid electrode, ionic liquid modified carbon paste electrode and carbon paste electrode

Ionic liquid, 1-heptyl-3-methylimidazolium hexafluorophosphate (HMIMPF₆), has been used to fabricate two new electrodes, carbon ionic liquid electrode (CILE) and ionic liquid modified carbon paste electrode (IL/CPE), using graphite powder mixed with HMIMPF₆ or the mixture of HMIMPF₆/paraffin liquid as the binder, respectively. The electrochemical behaviors of hydroquinone at the CILE, the IL/CPE and the CPE were investigated in phosphate buffer solution. At all these electrodes, hydroquinone showed a pair of redox peaks. The order of the current response and the standard rate constant of hydroquinone at these electrodes were as follows: CILE > IL/CPE > CPE, while the peak-to-peak potential separation was in an opposite sequence: CILE < IL/CPE < CPE. The results show the superiority of CILE to IL/CPE and CPE, and IL/CPE to CPE in terms of promoting electron transfer, improving reversibility and enhancing sensitivity. The CILE was chosen as working electrode to determine hydroquinone by differential pulse voltammetry, which can be used for sensitive, simple and rapid determination of hydroquinone in medicated skin cosmetic cream.     

Simultaneous determination of diclofenac and indomethacin using a sensitive electrochemical sensor based on multiwalled carbon nanotube and ionic liquid nanocomposite

Multiwalled carbon nanotube and ionic liquid-modified carbon ceramic electrode (MWCNT–IL|CCE) was employed for the simultaneous determination of diclofenac and indomethacin (IND). The measurements were carried out by differential pulse voltammetry method in optimal conditions. The prepared electrode showed appropriate voltammetric responses to DCF and IND with 0.225 V difference in the oxidation peak potentials, making fabricated electrode suitable for simultaneous determination of these compounds. The calibration curves were linear over a wide range of concentrations of each species including 0.05–50 μmol L^?1 for DCF and 1–50 μmol L^?1 for IND. Detection limits were found to be 18 and 260 nM for DCF and IND, respectively. The developed method having good stability and sensitivity was successfully applied for DCF and IND in commercial tablet as well as human blood plasma samples.     

氯盐离子液体水溶液的物理化学性质

离子液体是一类新型表面活性剂,研究离子液体+水体系的物性具有重要的意义。为此,本文测定了不同浓度和温度下［Bemim］［Cl］（氯化-1-甲基-3-苄基咪唑）,［C_nmim］［Cl］（氯化-1-甲基-3-烷基咪唑, n=4,14,16）,［BeiQu］［Cl］（氯化-N-苄基异喹啉）,［C_miQu］［Cl］（氯化-N-烷基异喹啉, m=4,8）等氯盐离子液体水溶液的密度、动力黏度、表面张力等物化性质。氯盐离子液体水溶液密度的变化趋势为咪唑类>异喹啉类。离子液体水溶液的黏度随着温度的升高而减小,随着浓度的升高而升高。在等温条件下,阳离子取代基相同时,离子液体水溶液的表面张力的变化趋势为咪唑类<异喹啉类。     

Entanglement network of chitin and chitosan in ionic liquid solutions

Concentrated solutions of a chitin from squid pens and of two commercial samples of chitosan were successfully prepared by using an ionic liquid 1‐butyl‐3‐methylimidazolium acetate as a solvent. The dynamic viscoelasticity data for the solutions exhibited rubbery plateaus, indicating the existence of entanglement network of chitin and chitosan in the solutions. To characterize the network, the values of the molecular weight between entanglements (M_e) for chitin and chitosan in the solutions were determined from the plateau moduli. Then the values of M_e in the molten state (M_e,melt), a material constant reflecting the inherent nature of polymer species, for chitin and chitosan were estimated to be 1.7 × 10³ and 3.0 × 10³, respectively. It was found that there was a significant difference in M_e,melt between chitin and chitosan. Compared with other polysaccharides such as cellulose and agarose in terms of the number of monosaccharide units between entanglements (N_unit), chitin had significantly smaller N_unit of 8, while chitosan had equivalent N_unit of 19. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2439–2443, 2013     

Correlation of carbon nanotube dispersability in aqueous surfactant solutions and polymers

In order to assess the dispersability of carbon nanotube materials, tubes produced under different synthesis conditions were dispersed in aqueous surfactant solutions and the sedimentation behaviour under centrifugation forces was investigated using a LUMiFuge stability analyzer. The electrical percolation threshold of the nanotubes after melt mixing in polyamide 6.6 was determined and the state of dispersion was studied. As a general tendency, the nanotubes having better aqueous dispersion stability showed lower electrical percolation threshold and better nanotube dispersion in the composites. This indicates that the investigation of the stability of aqueous dispersions is also able to give information about the nanotubes inherent dispersability in polymer melts, both strongly influenced by the entanglement and agglomerate structure of the tubes within the as-produced nanotube materials.The shape of the nanotubes in the aqueous dispersions was assessed using a SYSMEX flow particle image analyzer and found to correspond to the shape observed from cryofractured surfaces of the polymer composites.