One-dimensional Nanochannels Research Articles

Gradient doped polymer nanowire for moistelectric nanogenerator

A “moistelectric” nanogenerator based on gradient doped polypyrrole nanowire has been fabricated by concentration-controlled electro-deposition (CCED) technique. The specially designed composition and structure of the gradient doped polypyrrole nanowire endow it with huge surface area and one-dimensional transport nanochannels, which can largely facilitate the diffusion of water molecules to generate the dissociated charged ions as free carriers. For a polypyrrole nanowire with a diameter of 200 nm, it exhibits a high-output voltage in excess of 72 mV, a remarkable output current of 0.45 nA, and a maximum output power density of 103.13 mW cm−2 by area and 9.0 × 104 W kg−1 by mass under the ΔRH of 75%. On this basis, a vertically aligned gradient doped polypyrrole nanowire arrays show high current output of 0.14 μA without voltage drop. This work presents the first example that the power is gathered from moisture via polymer nanogenerators for energy-conversion application.

Sequence-regulated copolymerization based on periodic covalent positioning of monomers along one-dimensional nanochannels

The design of monomer sequences in polymers has been a challenging research subject, especially in making vinyl copolymers by free-radical polymerization. Here, we report a strategy to obtain sequence-regulated vinyl copolymers, utilizing the periodic structure of a porous coordination polymer (PCP) as a template. Mixing of Cu2+ ion and styrene-3,5-dicarboxylic acid (S) produces a PCP, [Cu(styrene-3,5-dicarboxylate)]n, with the styryl groups periodically immobilized along the one-dimensional channels. After the introduction of acrylonitrile (A) into the host PCP, radical copolymerization between A and the immobilized S is performed inside the channel, followed by decomposing the PCP to isolate the resulting copolymer. The predominant repetitive SAAA sequence in the copolymer is confirmed by monomer composition, NMR spectroscopy and theoretical calculations. Copolymerization using methyl vinyl ketone also provides the same type of sequence-regulated copolymer, showing that this methodology has a versatility to control the copolymer sequence via transcription of PCP periodicity at the molecular level.

Material hibrido organiko-ez-organiko fluoreszenteak aplikazio optikoetarako

Aplikazio optikoetarako material hibrido egokiak aurkitu nahian, koloratzaile desberdinak MgAPO-11 aluminofosfato ez-organikoan kapsulatu dira. Material zeolitiko honek AEL egitura dauka, dimentsio bakarreko nanokanal eliptiko oso estuak dituena, 6.5 x 4 Å2-ko diametrodunak; beraz, erabiliko diren koloratzaileen neurri molekularra kontuan izanik, oso estu kapsulatuak geratuko dira. Hori dela eta, koloratzailea sintesi-nahastera gehitzea beharrezkoa da kapsulatuak gera daitezen. Sintesi-metodo horren bidez koloratzaileak modu oso ordenatuan AELaren kanaletan harrapatzen dira 10 µm baino gehiagoko luzeradun partikuletan, euren ardatz molekular luzearekin kanalekiko paralelo, eta koloratzaile molekulen agregazioa saihesten da. Alde batetik, akridina (AC) eta pironina Y (PY) kromoforoak material zeolitikoan batera kapsulatu direnean, material hibrido oso fluoreszentea lortu da. Gainera, bi kromoforoen trantsizio-momentu dipolarrak bata bestearekiko perpendikularrak direnez, eta haien artean FRET energia-transferentzia eraginkorra gertatzen denez, partikulen emisio fluoreszentearen kolore-aldaketa ikus daiteke (zianetik berdera) materiala argi ultramorearekin kitzikatu ostean, bide optikoan detekzioaren aurretik koka daitezkeen polarizatzaileen norabidearen arabera. Azkenik, LDS 722 koloratzailea sartu da euskarri ez-organikoan eta emaitza gisa espektro elektromagnetikoaren alde gorrian igortzen duen material hibrido oso fluoreszentea eskuratu da. Bere etekin kuantikoa koloratzaileak disoluzio urtsuan azaltzen duena baino 50 bat aldiz altuagoa da, eta gainera, LDS 722ak optika ez-linealerako propietate intrintsekoak dituenez, eta partikuletan molekulek duten ordenamendu maila altua dela eta, material hibrido egokia lortu da bigarren harmonikoaren sorkuntzarako (SHG).

Flows in one-dimensional and two-dimensional carbon nanochannels: Fast and curious

Abstract

Thermal ring-opening polymerization of an unsymmetrical silicon-bridged [1]ferrocenophane in coordination nanochannels.

Thermal ring-opening polymerization of the unsymmetrically substituted [1]ferrocenophane was performed in one-dimensional nanochannels of porous coordination polymers (PCPs). In contrast to conventional thermal polymerization in bulk, formation of cyclic polymer was inhibited in the channels. In addition, the tacticity of the resulting polymer was dependent on the pore size of PCPs.

Mixed-Matrix Membranes Containing Carbon Nanotubes Composite with Hydrogel for Efficient CO2 Separation.

In this study, a carbon nanotubes composite coated with N-isopropylacrylamide hydrogel (NIPAM-CNTs) was synthesized. Mixed-matrix membranes (MMMs) were fabricated by incorporating NIPAM-CNTs composite filler into poly(ether-block-amide) (Pebax MH 1657) matrix for efficient CO2 separation. The as-prepared NIPAM-CNTs composite filler mainly plays two roles: (i) The extraordinary smooth one-dimensional nanochannels of CNTs act as the highways to accelerate CO2 transport through membranes, increasing CO2 permeability; (ii) The NIPAM hydrogel layer coated on the outer walls of CNTs acts as the super water absorbent to increase water content of membranes, appealing both CO2 permeability and CO2/gas selectivity. MMM containing 5 wt % NIPAM-CNTs exhibited the highest CO2 permeability of 567 barrer, CO2/CH4 selectivity of 35, and CO2/N2 selectivity of 70, transcending 2008 Robeson upper bound line. The improved CO2 separation performance of MMMs is mainly attributed to the construction of the efficient CO2 transport pathways by NIPAM-CNTs. Thus, MMMs incorporated with NIPAM-CNTs composite filler can be used as an excellent membrane material for efficient CO2 separation.

High-pressure behavior of bromine confined in the one-dimensional channels of zeolite AlPO4-5 single crystals.

We present a joint experimental and theoretical study on the high-pressure behavior of bromine confined in the one-dimensional (1D) nanochannels of zeolite AlPO4-5 (AFI) single crystals. Raman scattering experiments indicate that loading bromine into AFI single crystals can lead to the formation of bromine molecular chains inside the nanochannels of the crystals. High-pressure Raman and X-ray diffraction studies demonstrate that high pressure can increase the length of the confined bromine molecular chains and modify the inter- and intramolecular interactions of the molecules. The confined bromine shows a considerably different high-pressure behavior to that of bulk bromine. The pressure-elongated bromine molecular chains can be preserved when the pressure is reduced to ambient pressure. Theoretical simulations explain the experimental results obtained from the Raman spectroscopy and X-ray diffraction studies. Furthermore, we find that the intermolecular distance between confined bromine molecules gradually becomes comparable to the intramolecular bond length in bromine molecules upon compression. This may result in the dissociation of the bromine molecules and the formation of 1D bromine atomic chains at pressures above 24 GPa. Our study suggests that the unique nanoconfinement has a considerable effect on the high-pressure behavior of bromine, and the confined bromine species concomitantly enhance the structural stability of the host AFI single crystals.

Chaperone-Assisted Formation of Cucurbit[8]uril-Based Molecular Porous Materials with One-Dimensional Channel Structure.

Exploiting "chaperone molecule" to navigate the successful assembly energy landscapes has been extensively used in biological systems, whereas in artifical supramolecular systems the "chaperone-assisted" assembly strategy to be used for the synthesis of materials with novel structures or the structures to be hardly prepared by "conventional" methods are still far from realizing the potential functions. In this work, we present a new example of small organic molecule acting as "chaperone molecule" in the facile formation of organic molecular porous materials. This porous material is composed of pure cucurbit[8]uril (CB[8]) macrocycle and possesses a honeycomb-like structure with an isolated and relatively large one-dimensional (1D) nanochannel. Moreover, it has good chemical and thermal stability, and shows a good adsorption capability for large molecule loading. Importantly, with the assistance of chaperone molecules, pure CB[8] could also be recycled even from a complex aqueous solution, demonstrating a powerful purification method of CB[8] from complex systems.

ESR study of molecular orientation and dynamics of TEMPO derivatives in CLPOT 1D nanochannels.

The molecular orientations and dynamics of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO) radical derivatives with large substituent groups at the 4-position (4-X-TEMPO) in the organic one-dimensional nanochannels within the nanosized molecular template 2,4,6-tris(4-chlorophenoxy)-1,3,5-triazine (CLPOT) were examined using ESR. The concentrations of guest radicals, including 4-methoxy-TEMPO (MeO-TEMPO) or 4-oxo-TEMPO (TEMPONE), in the CLPOT nanochannels in each inclusion compound (IC) were reduced by co-including 4-substituted-2,2,6,6-tetramethylpiperidine (4-R-TEMP) compounds at a ratio of 1 : 30-1 : 600. At higher temperatures, the guest radicals in each IC underwent anisotropic rotational diffusion in the CLPOT nanochannels. The rotational diffusion activation energy, Ea , associated with MeO-TEMPO or TEMPONE in the CLPOT nanochannels (6-7 kJ mol(-1) ), was independent of the size and type of substituent group and was similar to the Ea values obtained for TEMPO and 4- hydroxy-TEMPO (TEMPOL) in our previous study. However, in the case in which TEMP was used as a guest compound for dilution (spacer), the tilt of the rotational axis to the principal axis system of the g-tensor, and the rotational diffusion correlation time, τR , of each guest radical in the CLPOT nanochannels were different from the case with other 4-R-TEMP. These results indicate the possibility of controlling molecular orientation and dynamics of guest radicals in CLPOT ICs through the appropriate choice of spacer. Copyright © 2016 John Wiley & Sons, Ltd.

The spatial distribution of the photostability of thionine in zeolite L nanochannels investigated by Photobleaching Lifetime Imaging Microscopy.

Dye photobleaching is a photochemical reaction that can be investigated locally using fluorescence microscopy techniques. In this study, a user-friendly computational tool to assist photobleaching experiments called Photobleaching Lifetime Imaging Microscopy (PbLIM) is presented. With this tool it is possible to recover the photobleaching kinetics spatially, where a photobleaching lifetime is generated for each pixel of the image. Our model was applied to the photobleaching process of thionine encapsulated into the one-dimensional nano-channels of Zeolite L (ZL), from where we gained insight into the molecular oxygen distribution inside the ZL channels, as well as the detailed photobleaching of the confined thionine.

The controlled synthesis of polyglucose in one-dimensional coordination nanochannels.

We demonstrate a feasible method for the preparation of polyglucose (PGlc) with controlled structures, where the polymerization of glucose monomers was performed using one-dimensional nanochannels of [La(1,3,5-benzenetrisbenzoate)(H2O)]n (1). Cationic ring-opening polymerization of 1,6-anhydro-β-D-glucose (levoglucosan) using 1 gave a quasi-linear PGlc, which contrasts highly with the results obtained from conventional polymerizations in bulk and solution. The regulated structure of PGlc prepared using the PCP led to a remarkable improvement in the processability and thermal stability of PGlc, which is useful in applications as a bioplastic.

Fabrication of Nanochannels.

Nature has inspired the fabrication of intelligent devices to meet the needs of the advanced community and better understand the imitation of biology. As a biomimetic nanodevice, nanochannels/nanopores aroused increasing interest because of their potential applications in nanofluidic fields. In this review, we have summarized some recent results mainly focused on the design and fabrication of one-dimensional nanochannels, which can be made of many materials, including polymers, inorganics, biotic materials, and composite materials. These nanochannels have some properties similar to biological channels, such as selectivity, voltage-dependent current fluctuations, ionic rectification current and ionic gating, etc. Therefore, they show great potential for the fields of biosensing, filtration, and energy conversions. These advances can not only help people to understand the living processes in nature, but also inspire scientists to develop novel nanodevices with better performance for mankind.

Transpiration of Water Molecules through Molecule-Based Porous Crystals with One-Dimensional Nanochannels

Abstract Synthetic molecular crystals with one-dimensional nanoporous channels containing H2O molecules act as model systems for pores such as aquaporin-1 in cell membranes. The structural characteristics of water molecular clusters (WMCs) were investigated using X-ray crystal analysis of {[NiII(cyclam)]3(TMA)2·35–34 H2O}n (2) (TMA: trimesate, cyclam: 1,4,8,11-tetraazacyclotetradecane) in a closed glass capillary to adjust the saturated humidity. The structural phase transition of WMCs with temperature depends only on the H2O structures around the centre, not on those in the primary hydrate layer nearest to the outer wall. The centre of a WMC was filled with H2O molecules under saturated humidity conditions; however, in air, the WMC had a nanotube-like structure with a vacant space. Thus, the centre portion of a WMC probably contains volatile and mobile H2O molecules. Therefore, we investigated the rapid proton conductivity using alternating current impedance and microwave spectroscopy and also carried out a transpiration experiment for transferring the mobile H2O molecules. The microwave spectroscopy results for 2 indicated no isotope effect, which would be observed by the rapid motion of H2O molecules without the breaking of hydrogen bonds between two site-disordering positions above the phase transition temperature. The results indicated reasonable water transpiration ability of the single crystal through its nanochannels; this property can be useful as a working principle to understand applications such as the desalination of seawater.

Squeezing xenon into phenylether bis-urea nanochannels

One-dimensional nanochannels, hundreds of microns in persistence length but with elliptical cross-sectional dimensions of only ∼3.7 Å × 4.8 Å, are formed by the columnar assembly of phenylether bis-urea macrocycles. Hyperpolarized Xe-129 NMR is utilized to investigate the Xe atom packing and Xe diffusion inside the needle shaped crystals. The elliptical channel structure produces a Xe-129 powder pattern characteristic of an asymmetric chemical shift tensor extending to well over 300 ppm with respect to the gas phase, reflecting the highly anisotropic electronic environment and extreme confinement of the atom. Consistent with the simple geometrical criterion, hyperpolarized tracer exchange NMR data reveals single-file diffusion in the bis-urea nanochannels.

Radical Copolymerization Mediated by Unsaturated Metal Sites in Coordination Nanochannels.

Radical copolymerization of methyl methacrylate (MMA) and styrene was performed in [Tb(1,3,5-benzenetrisbenzoate)]n with coordinatively unsaturated metal sites (UMS) immobilized along the one-dimensional nanochannels. A drastic increase in the proportion of MMA units in the resulting copolymers was obtained compared with that obtained from the corresponding solution polymerization systems. Simultaneous coordination of MMA to the UMS is the key to increasing the MMA proportion during the copolymerization in the nanochannels, which was demonstrated by variable temperature IR measurements and several controlled experiments.

Crystalline Bis-urea Nanochannel Architectures Tailored for Single-File Diffusion Studies

Urea is a versatile building block that can be modified to self-assemble into a multitude of structures. One-dimensional nanochannels with zigzag architecture and cross-sectional dimensions of only ∼3.7 Å × 4.8 Å are formed by the columnar assembly of phenyl ether bis-urea macrocycles. Nanochannels formed by phenylethynylene bis-urea macrocycles have a round cross-section with a diameter of ∼9.0 Å. This work compares the Xe atom packing and diffusion inside the crystalline channels of these two bis-ureas using hyperpolarized Xe-129 NMR. The elliptical channel structure of the phenyl ether bis-urea macrocycle produces a Xe-129 powder pattern line shape characteristic of an asymmetric chemical shift tensor with shifts extending to well over 300 ppm with respect to the bulk gas, reflecting extreme confinement of the Xe atom. The wider channels formed by phenylethynylene bis-urea, in contrast, present an isotropic dynamically average electronic environment. Completely different diffusion dynamics are revealed in the two bis-ureas using hyperpolarized spin-tracer exchange NMR. Thus, a simple replacement of phenyl ether with phenylethynylene as the rigid linker unit results in a transition from single-file to Fickian diffusion dynamics. Self-assembled bis-urea macrocycles are found to be highly suitable materials for fundamental molecular transport studies on micrometer length scales.

Tin Oxides with Nano and Micron-Sized Pores for Functional Electrochemical Devices

Metal oxides with one-dimensional (1-D) nano-channels have drawn much attention as potential electrode materials for high performance functional electrochemical devices. This is mainly because the large surface area of nanostructures and the 1-D pathway of reactants/products in channels result in low activation and concentration polarizations, respectively. In spite of such advantages, the expected high rate and high efficient operation of the devices adopting the electrodes with nano-channeled structure might not be quite sustainable particularly when the rate of surface reaction far exceeds that of mass transport through the channels. That is, the reactants/products would be seriously depleted/accumulated in the channel at the very high rate of surface reaction, possibly leading to the significant decrease in total reaction rate. One way to solve this problem is to prepare the hybrid porous structure composed of both nano-sized and micron-sized pores, where the latter efficiently provides the reactants to or receives the products from the nano-channels. It has been known that an anodic oxidation process is a quite effective way to create the metal oxide films with well-defined 1-D nano-channeled structure. Among the anodic metal oxides with 1-D structure, tin oxide is worthy of attention due to its widespread use in various applications, such as catalysis, gas sensing and energy storage. In this work, meso- and macro- hybrid porous structure is created without a template by an anodic oxidation process. From the experimental results, it is suggested that the substrate, the anodizing time, the thickness of the pre-anodized tin have an important effect on the size and density of macro-pores in hybrid porous structure. For example, the well-defined meso/macro hybrid porous tin oxides can be created when silicon was used as a substrate to anodize tin thin film. On the basis of the mechanical analysis of the different substrates and different thicknesses of tin film on them, it is suggested that the substrate with high elastic modulus might result in high compressive stress to the anodic tin oxide and generate local cracks in the initial stage of anodizing process, which grow to macro-pores with semispherical shape in the later stage. From two step anodizing process including the intervening selective etching of tin oxide, highly-open meso/macro hybrid porous tin oxide is successfully prepared. Anodic tin oxide formed under the macro-pores has meso-porous structure with radial shape, ideally suited for high rate and high efficient functional electrochemical devices.

Dynamics of TEMPOL Radicals in TPP 1D Nanochannels and Different Molecular Orientation from Other TEMPO Derivatives

Abstract The molecular orientation and dynamics of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPOL) radicals in one-dimensional (1D) nanochannels of the crystal of tris(o-phenylenedioxy)cyclotriphosphazene (TPP) were examined using electron spin resonance (ESR) measurements. TEMPOL radicals in the TPP nanochannels performed rotational diffusion motion not around the principal y axis of the g-tensor, as observed in most cases of TEMPO derivatives, but approximately around the principal z axis with much larger activation energy.

Physical Properties of Self-Assembled Porous Alumina Structures Filled with Iodine

Self-assembled porous alumina structures (por Al2O3) were prepared by two-step anodization process and characterized by scanning electron microscopy.Filling quasi one-dimensional parallel nanochannels of por Al2O3 host matrixwith iodine guest substance by vapor phase adsorption method resulted inthe formation of I/por Al2O3 nanocomposite. Electrical properties of thesenanocomposite samples were studied by alternating-current measurements ata frequency of 1 kHz. Ellipsometric measurements were carried out in thespectral range 350–1000 nm. Structural transition of iodine species from thechain structures to molecular iodine was found in I/por Al2O3 nanocompositeat ∼ 70 ◦C.

Columnar nanostructured polymer films containing ionic liquids in supramolecular one‐dimensional nanochannels

ABSTRACTIonic liquids have attracted a considerable attention as the next generation electrolytes for energy devices. We have developed new free‐standing and nanostructured polymer films in which ionic liquids are confined into one‐dimensionally ordered nanochannels. These polymer films have been obtained by photopolymerization of hydrogen‐bonded supramolecular columnar liquid‐crystalline self‐assemblies of an imidazolium‐based ionic liquid and a wedge‐shaped diol compound containing polymerizable groups. The macroscopically parallel alignment of the columnar structures on a glass substrate has been achieved by the application of mechanical shearing, and subsequently fixed into polymer films by UV irradiation. This ionic liquid‐containing polymer film exhibits higher ionic conductivity than that of the previously reported one‐dimensional polymer film obtained by in situ photopolymerization of a covalent‐type columnar liquid‐crystalline imidazolium salt. The noncovalent supramolecular approach to one‐dimensionally ion‐conductive polymer films has led to improvement on conductive properties. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 366–371