Self-assembling Synthesis of Vanadium Oxide Nanotubes and Simple Determination of the Content of V(IV)

High-yielding low-cost vanadium oxide nanotubes were prepared by the hydrothermal self-assembling process from vanadium pentoxide and organic molecules as structure-directing templates.Moreover,a new method was discovered for determining the content of V (IV) in vanadium oxide nanotubes by thermogravimetric analysis (TGA).This method is simple,precise and feasible and can be extended to determine the content of low oxidation state in the other transition metal oxide nanomaterials.

Hollow tubes constructed by carbon nanotubes self-assembly for CO_(2) capture

Carbon nanotubes(CNTs)have garnered significant attention in the fields of science,engineering,and medicine due to their numerous advantages.The initial step towards harnessing the potential of CNTs involves their macroscopic assembly.The present study employed a gentle and direct self-assembly technique,wherein controlled growth of CNT sheaths occurred on the metal wire’s surface,followed by etching of the remaining metal to obtain the hollow tubes composed of CNTs.By controlling the growth time and temperature,it is possible to alter the thickness of the CNTs sheath.After immersing in a solution containing 1 g/L of CNTs at 60℃ for 24 h,the resulting CNTs layer achieved a thickness of up to 60μm.These hollow CNTs tubes with varying inner diameters were prepared through surface reinforcement using polymers and sacrificing metal wires,thereby exhibiting exceptional attributes such as robustness,flexibility,air tightness,and high adsorption capacity that effectively capture CO_(2) from the gas mixture.

Structure and Properties of Self-assembled Narural Rubber/Multi-walled Carbon Nanotube Composites

Natural rubber （NR）/multi-walled carbon nanotube （MWCNTs） composites were prepared by combining self-assembly and latex compounding techniques.The acid-treated MWCNTs （H2SO4：HNO3=3：1,volume ratio） were self-assembled with poly （diallyldimethylammonium chloride） （PDDA） through electrostatic adhesion.In the second assembling,NR/MWCNTs composites were developed by mixing MWCNTs/PDDA solution with NR latex.The results show that MWCNTs are homogenously distributed throughout the NR matrix as single tube and present a great interfacial adhesion with NR phase when MWCNTs contents are less than 3 wt%.Moreover,the addition of the MWCNTs brings about the remarkable enhancement in tensile strength and crosslink density compared with the NR host,and the data peak at 2 wt% MWCNTs loadings.When more MWCNTs are loaded,aggregations of MWCNTs are gradually generated,and the tensile strength and crosslink both decrease to a certain extent.

Self-assembled Carbon Nanotube/Silicone Composite Films and Their Electrical Properties for Electrical Device

Novel composites were synthesized using AEPTES （3-（2-aminoethylamino）propyltriethoxysilane）, which behaves as an excellent dispersant for MWCNTs （multiwall carbon nanotubes） in polymer film matrices. The thickness of the synthesized nanocomposite films ranged from 50 to 70 lam, having well-dispersed MWCNTs. Increasing the AEPTES concentration from 0.0196 to 0.0300 M, increased the amine content and the dispersion of MWCNTs. The film synthesized at 0.0300 M AETPES exhibited the greatest degree of dispersion among the three samples, which is consistent with a self-assembled silane group interacting with the MWCNT surface.

Study of enzyme biosensor based on carbon nanotubes modified electrode for detection of pesticides residue

The paper describes a controllable layer-by-layer （LBL） self-assembly modification technique of multi-walled carbon nanotubes （MWNTs） and poly（diallyldimethylammonium chloride） （PDDA） towards glassy carbon electrode （GCE）, Acetylcholinesterase （ACHE） was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected by using i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrode with 0.01U activity value and the detection limit of carbaryl is 10^- 12 g L ^-1 so the enzyme biosensor showed good properties for pesticides residue detection.

Layer-by-layer electrostatic selfassembly of anionic and cationic carbon nanotubes

The layer-by-layer(LBL) self assembly of anionic and cationic multi-walled carbon nanotubes(MWNTs) through electrostatic interaction has been carried out to fabricate all-MWNT multilayer films.The alternate uniform assembly of anionic and cationic MWNTs was investigated by UV-vis spectroscopy.Scanning electron microscopy(SEM) images displayed the growth of the MWNT films.

Synthesis and Characterization of Various Protein <i>α</i>-Lactalbumin Nanotubes Structures by Chemical Hydrolysis Method

New water-based nanofluids including unparalleled milk protein α-lactalbumin hollow nano-bio-tubes using low cost, available and advanced partial chemical hydrolysis strategy in bottom-up nano-assembly have been employed in this work. The aqueous sol-gel chemistry in nanotechnology which we selected for this goal offers new fabrication as interesting smart protein nanotubes. The kinds of nanometer sized tubular structures such as waved, helically coiled, bent, bamboo-shaped, bead-like and branched single-walled protein nanotubes (SWPNTs) with a range of 3 - 8 nm in outer diameters were produced by this method. Complete characterization for natural produced nanotubes including SEM, TEM images, G bond and D bond in Raman spectroscopy, XRD patterns, DLS (Dynamic Light Scattering) and FTIR analysis were evaluated which they are most significant experiments in synthesized protein nanotubes soluble in clear water nanofluids and stabilization of transparent nanofluids was proved within more than one year after preparation. Various necessary ligand ion salts such as Mn2+, Zn2+ and Ca2+ or mixtures as bridge makers and producing biological self-assembly hollow SWPNTs were performed and we focused on new chemical technology under specific acidic hydrolysis method not conventional enzymatic proteolysis and applying surfactants, pH reagent, Tris-HCl buffer, polar solvent which could be produced by β-sheet stacked hydrolysed protein α-lactalbumin mechanism under appropriate conditions to achieving high efficiency new protein nanotubes skeleton. They can be promising materials applied in food science, diet nutrition, nanomedicine, nano-biotechnology and surgery.

Analysis of Carbon Nanotubes Produced by Pyrolysis of Composite Film of Poly (Vinyl Alcohol) and Modified Fly Ash

We determined the catalytic function of chemically modified fly ash (MFA) for the growth of carbon nanotube (CNT) ropes with ~54% yield by the pyrolysis of the composite film of poly (vinyl alcohol) (PVA) at 500°C for 10 min under 2 L/min flow of nitrogen. Fly ash was treated with 2M sodium hydroxide to have MFA and used with PVA to fabricate the composite film by aqua casting. CNT was analyzed using SEM, TEM, XPS and Raman spectroscopy. The growths of CNT on MFA surfaces were visualized with different geometric self-assembly, e.g., bundles of CNT in ropes, twisted ropes, Y-branch ropes and staked-cone sheet. Thus, the mixtures of CNT ropes and MFA are a potential filler material for fabricating composites with polymer and metal.

Molecular Dynamics Study of Dipalmitoylphosphatidylcholine Lipid Layer Self-Assembly onto a Single-Walled Carbon Nanotube

Single-walled carbon nanotubes(SWNTs)are possible nano-injectors and delivery vehicles of molecular probes and drugs into cells.In order to explore the interaction between lipid membranes and carbon nanotubes,we investigate the binding mechanism of dipalmitoylphosphatidylcholine(DPPC)with SWNTs by molecular dynamics.In low concentration range simulations,the DPPC molecules form a supramolecular two-layered cylindrical structure wrapped around the carbon nanotube surface.The hydrophobic part of DPPC is adsorbed on the surface of the nanotube,and the hydrophilic top is oriented towards the aqueous phase.For higher concentration ranges,the DPPC molecules are found to form a supramolecular multi-layered structure wrapped around the carbon nanotube surface.At the saturation point a membrane-like structure is self-assembled with a width of 41.4Å,which is slightly larger than the width of a cell membrane.Our study sheds light on the existing confl icting simulation data on adsorption of single-chained phospholipids.

Detection of dopamine using self-assembled diazoresin/single-walled carbon nanotube modified electrodes

Ultrathin films of diazoresin （DR）/single-walled carbon nanotube （SWNT） were fabricated on thioglycollic acid （TGA） decorated gold （Au） electrodes by the self-assembly method combined with the photocrosslinking technique. The electrochemical behavior of dopamine （DA） at the DR/SWNT modified electrodes was studied using the cyclic voltammetry （CV） and differential pulse voltammetry （DPV） methods. Under the optimal conditions, a linear CV response to DA concentration from 1 p, mol/L to 40 μmol/L was observed, and the detection limit of DA was 2.1 ×10-3 μmol/L via the DPV method in the presence of 10μmol/L of uric acid （UA） or 2.5 × 10-3 μmol/L via the DPV method in the presence of 10 μmol/L of ascorbic acid （AA）. Moreover, the modified electrodes exhibited good reproducibility and sensitivity, demonstratinz its feasibilitv for analytical ourooses.

Length-dependent alignment of large-area semiconducting carbon nanotubes self-assembly on a liquid–liquid interface

Aligned arrays of semiconducting carbon nanotubes(s-CNTs)with high homogenous density and orientation are urgently needed for high-performance carbon-based electronics.Herein,a length-controlled approach using combined technologies was developed to regulate the s-CNT length and reduce the length distribution.The impact of different lengths and length distributions was studied during aligned self-assembly on a liquid–liquid confined interface was investigated.The results show that short s-CNTs with a narrow distribution have the best alignment uniformity over the large scale.The optimized and aligned s-CNT array can reach a density as high as 100 CNTs·μm−1 on a 4-inch wafer.The field-effect transistor(FET)performance of these optimized s-CNT arrays was 64%higher than arrays without length-control.This study clarified that rational control of s-CNTs with desired length and length distribution on the aligned self-assembly process within the liquid–liquid confined interface.The results illustrate a solid foundation for the application of emerging carbon-based electronics.

Formation of One-Dimensional van der Waals Heterostructures via Self-Assembly of Blue Phosphorene Nanoribbons to Carbon Nanotubes

Van der Waals heterostructures composed of low-dimensional atomic layers host rich physics for new device applications,such as magic-angle twisted bilayer graphene and coaxial multi-walled hetero-nanotubes.Aside from exploring their abnormal physical behavior,fabrication of such structures also presents a great challenge to this area,owing to the subtle and sensitive interactions among neighboring layers.Here we show by molecular dynamics simulations that narrow blue phosphorene nanoribbons can be encapsulated into carbon nanotubes driven by van der Waals interactions and form one-dimensional heterostructures.It shows that by varying carbon nanotube diameters and nanoribbon width,the nanoribbons can either retain their original straight structures or twist into tubular structures.Wrapping phases are also observed for large-sized blue phosphorus.It is found that the underlying mechanism originates from the competition between van der Waals energy and bending energy induced by tube curvature.A phase diagram of the resultant 1D structure is thus obtained based on a simple analysis of energetics.The results are expected to stimulate further experimental efforts in fabricating one-dimensional van der Waals heterostructues with desired functionality.

Large-Scale Self-Assembled Ag Nanotubes

A high yield of silver nanotubes with large aspect ratio were conveniently synthesized via an organic-assist solvothermal preparation technique using polyvinyl pyrrolidone （PVP） as a capping reagent and architecture soft-template. The molecular ratio between the repeating unit of PVP and AgNO3 plays a crucial role in determining the geometric shape of the product. Such novel-type Ag nanotubes were self-assembled by Ag nanoparticles, which had largely similar crystallographic orientation, forming a texture. The fact that nanoparticles without anisotropic crystal structures can form such superstructures by self-assembly may open a window for understanding a range of nanotube formation processes.

Fabrication of Ordered Magnetite-Doped Rare Earth Fluoride Nanotube Arrays by Nanocrystal Self-Assembly

We describe a nanocrystal self-assembly method for the preparation of rare earth fluoride nanotube(ReF-NT)arrays and magnetite-doped rare earth fluoride nanotubes(Fe_(3)O_(4)ReF-NTs)by using porous anodic aluminum oxide(AAO)as a hard template.The ReF-NTs can be simply prepared by the impregnation of-NaYF_(4)nanocrystals doped with Yb and Er into the channels of the porous AAO and show a highly ordered nanotube array and excellent upconversion(UC)fluorescence properties.Similarly,the Fe_(3)O_(4)ReF-NTs are obtained by the self-assembly of a mixture of Fe_(3)O_(4)and Yb/Er doped-NaYF4 nanocrystals in the AAO pore channels and have a uniform dispersion of magnetite nanocrystals on the rare earth fluoride tube matrix and possess multifunctional magnetic/UC properties.The diameter of these nanotubes can be varied from 60 nm to several micrometers depending on the pore size of the AAO template.The wall thickness can be increased from 10 to 35 nm by increasing the concentration of nanocrystals from 0.02 to 0.4 mmol/L,while the morphology of the nanotubes can be varied from small isolated domain structures to percolating domains and eventually to compact domains.A template-directed formation mechanism is proposed and the quantitative predictions of the model for such self-assembled nanocrystal spreading processes are demonstrated.Strong UC fluorescent emissions are realized for the nanotube arrays and multifunctional nanotubes with UC excitation in the near-infrared(NIR)region.A strong magnetic response of the multifunctional nanotubes is observed,which facilitates their easy separation from solution by magnetic decantation using a permanent magnet.

Defect- and dopant-controlled carbon nanotubes fabricated by self-assembly of graphene nanoribbons

Molecular dynamics simulations showed that a basal carbon nanotube can activate and guide the fabrication of single-walled carbon nanotubes （CNTs） on its internal surface by self-assembly of edge-unpassivated graphene nanoribbons with defects. Furthermore, the distribution of defects on self-assembled CNTs is controllable. The system temperature and defect fraction are two main factors that influence the success of self-assembly. Due to possible joint flaws formed at the boundaries under a relatively high constant temperature, a technique based on increasing the temperature is adopted. Self-assembly is always successful for graphene nanoribbons with relatively small defect fractions, while it will fail in cases with relatively large ones. Similar to the self-assembly of graphene nanoribbons with defects, graphene nanoribbons with different types of dopants can also be self-assembled into carbon nanotubes. The finding provides a possible fabrication technique not only for carbon nanotubes with metallic or semi-con- ductive properties but also for carbon nanotubes with electromagnetic induction characteristics.

From Carbon Nanotube Crystals to Carbon Nanotube Flowers

We have investigated the very initial deposition stages of chemical vapor deposition （CVD） with ferrocene （Fe（CsH5）2） and xylene （C8H10） for growing carbon nanotubes, and made clear that the mechanism for the self-organization behaviors of nanotubes at different growth stages by this approach. For instance, the organization of nanotubes into flower-like structures at prolonged deposition is developed from the crystal-like structures formed at early growth stages, both of which are closely related to and determined by the very initial deposition stages of this CVD approach. Based on this approach, ways have been established to build up different architectures of carbon nanotubes, by controlling the initial deposition stages of the CVD process, with which we have realized the selective growth of self-organized carbon nanotube structures. This study provides a new idea for growing carbon nanotube architectures by CVD.

A chirality indicator for the walls and the surfaces of silica nanotubes

Single-handed helical silica nanotubes were prepared according to the literature procedures,using the self-assemblies of a pair of chiral cationic low-molecular-weight gelators as the templates.A chirality indicator,4,4＇-bis（triethoxysilyl）-1,1＇-biphenyl,was developed to determine the chirality of the silica nanotubes.The chirality of the surfaces and the bulky walls of the silica nanotubes were understood from the twist of the biphenylene rings.

How Small DNA Minicircles Can Be Applied to Construct DNA Nanotubes？

DNA as a life＇s information carrier can be modified into geometrically fine nanostructures via self-assembly of designed nucleotides with specified length. In this work, three DNA minicircles with designed lengths of 48-nt, 50-nt, and 52-nt, are directed to self-assemble into nanotubes after hybridization with staple strands, following the folding strategy with each double crossover （DX） at 2.5 turns. Much smaller DNA minicircles such as the 32-nt ring are highly rigid once they form double helices, therefore they lack the flexibility to form finely ordered nanotubes. In the case of nanotubes comprising of 52-nt minicircles, most nanotubes were 800 nm long and 20% were up to 2 p.m, whereas the nanotubes composed of 50 base pair subunits and 48 base pair subunits with the DX at frustrated 2.5 turns showed relatively shorter nanotubes at 700 and 600 （or 500） nm, respectively.

Self-Organized Growth of Complex Nanotube Patterns on Crystal Surfaces

The organization of carbon nanotubes into well-dened straight or curved geometries and arrays on surfaces is a critical prerequisite for their integration into nanocircuits and a variety of functional nanosystems.We review the recent development of a new approach to carbon nanotube organization based on self-organized growth directed by well-defined crystal surfaces,or“nanotube epitaxy”.We identify three different modes of surface-directed growth,namely by atomic rows,atomic steps,and nanofacets.Particular emphasis is given here to the combinations of such surface-directed growth with external forces-like those exerted by an electriceld or gas o-wfor the creation of well-de-ned complex geometries,including crossbar architectures,serpentines,and coils.

Novel Cyclopeptide Bolaamphiphile for Constructing Supramolecular Nanotubes

A novel dicyclopeptide-based bolaamphiphile was synthesized.The hydrophilic cyclopeptide fragments were linked to an alkyl chain 1,6-bis(maleimido)hexane,which acted as a hydrophobic spacer.The transmission electron microscopy (TEM) observation indicated that the cyclopeptide bolaamphiphile (CPB) self-assembled into the nanotubes with a thickness of about 3 nm.Based on the optimized molecular conformation obtained via MM2 method,the length of CPB was demonstrated to be around 4 nm,implying that the nanotubes were single-walled.Fourier transform infrared spectroscopy (FT-IR) and circular dichroism (CD) analysis showed that the cyclopeptides in CPB mainly acted as the hydrophilic headgroups,rather than providing the well-ordered hydrogen bonding interaction responsible for β-sheet conformation.To investigate the special self-assembly behavior of CPB,the single cyclopeptide (CP) without the connection of the linker was synthesized.Further investigation indicated that the CP molecules can not form tubular structures but nanofibers.