Don Futaba, National Institute of Advanced Industrial Science and Technology
Annick Loiseau, Laboratoire d'Etude des Microstructures
Yoke Khin Yap, Michigan Technological University
Ming Zheng, National Institute of Standards and Technology
Symposium Support Hummingbird Scientific
The Multi-Scale Technologies Institute (MuSTI) - Michigan Technological University
MM2: Advanced Characterization
Yoke Khin Yap
Tuesday PM, April 22, 2014
Moscone West, Level 2, Room 2006
2:30 AM - *MM2.01
In-situ Electron Microscopy of One- and Two-Dimensional Structures of Carbon and Related Materials
Florian Banhart 1 Julio A. Rodriguez-Manzo 1 2 Ovidiu Cretu 1 3 Ferdaous Ben Romdhane 1
1University of Strasbourg Strasbourg France2University of Pennsylvania Philadelhpia USA3National Institute of Advanced Industrial Science and Technology Tsukuba, Ibaraki JapanShow Abstract
In-situ transmission electron microscopy gives valuable information about many important issues of carbon nanomaterials. Dynamic phenomena are getting accessible to direct observation. The presentation shows the application of different in-situ techniques such as heating, irradiation, or electrical probing of carbon and related nanostructures under observation in the microscope. The focus is on one- and two-dimensional carbon nanomaterials such as monoatomic carbon chains and graphene and on related non-carbon materials such as two-dimensional silica.
The nucleation and growth of carbon nanotubes or graphene can be made visible in the solid-state growth of carbon structures on catalytically active metals . The heating of suitable metal-carbon precursors allows us to observe the growth of single- or multi-wall carbon nanotubes on small metal particles or the growth of mono- and multilayer graphene on flat metal surfaces. Electron irradiation can be used to tailor the precursor systems prior to the growth of carbon. Diffusion processes, i.e., carbon atoms in or on metals or, conversely, metal atoms on graphitic surfaces, play a decisive role and can also be observed in-situ .
Interesting yet hardly explored carbon species are linear sp1-bonded chains of carbon atoms. The in-situ electrical probing by an STM tip in a TEM allows us to generate such carbon chains that are the only real one-dimensional allotrope of carbon . The chains can be pulled out from graphenic aggregates by electrically biased metal contacts. While the chains are generated and observed, their electrical characteristics can be measured. The analysis of current-voltage curves shows that a Peierls distortion leads to an opening of the bandgap so that the chains are normally semiconducting.
Two-dimensional silicon dioxide films have recently attracted much interest due to their hexagonal structure that has many common characteristics with graphene, e.g., the same types of non-hexagonal defects. A new route is explored towards the synthesis of 2D silica in a solid-state growth process that is carried out in-situ in a TEM . The experiments allow us to obtain detailed information on the nucleation, growth, and the epitaxial relationship with the crystallographic symmetry of the metal surface.
 J. A. Rodríguez-Manzo, C. Pham-Huu and F. Banhart, ACS Nano 5, 1529 (2011).
 O. Cretu, A.V. Krasheninnikov, J.A. Rodríguez-Manzo, R. Nieminen and F. Banhart, Phys. Rev. Lett. 105, 196102 (2010).
 O. Cretu, A. R. Botello-Mendez, J.-C. Charlier, I. Janowska, C. Pham-Huu, F. Banhart, Nano Lett. 13, 3487 (2013).
 F. Ben Romdhane, T. Björkman, J. A. Rodríguez-Manzo, O. Cretu, A. V. Krasheninnikov, F. Banhart, ACSNano 7, 5175 (2013).
3:00 AM - *MM2.02
Structural Investigations of Carbon Nanotubes at the Atomic Level
Jamie Warner 1
1University of Oxford Oxford United KingdomShow Abstract
Carbon nanotubes (CNTs) have rich structural diversity represented by their chirality range and number of walls. The electronic properties of CNTs are heavily influence by these structural characteristics and therefore it is important to study the atomic configuration with detail. Defects, such as vacancies and bond rotations perturb the perfect crystalline structure of CNTs and influence properties, therefore prompting their study. In this talk I will show how the atomic structure of CNTs can be imaged in high detail using aberration-corrected transmission electron microscopy (AC-TEM) to answer important structure questions. We utilize Oxford's JEOL 2200MCO AC-TEM, equipped with an image aberration corrector and bespoke monochromation of the electron beam at an accelerating voltage of 80 kV. The chirality of individual nanotubes are determine directly from AC-TEM images, which also provide spatial mapping of the atomic structure by tracking deviations in the Moire patterns. By obtaining high quality images of CNTs using AC-TEM, we have been able to reveal the presence of shear strain in single-walled carbon nanotubes arising from bending, the presence of defects hidden within the inner wall tubes of double-walled carbon nanotubes, and the presence of molecules attached to the outside (and inside) of SWNTs.
3:30 AM - MM2.03
Atomic Resolution SWCNT Nucleation Steps on Faceted Catalyst Particle Reveal Potential for Chirality Control
Pin ann Lin 1 2 Matthieu Picher 1 2 Jonathan Winterstein 2 Renu Sharma 2
1University of Maryland College Park USA2National Institute of Standards and Technology Gaithersburg USAShow Abstract
Carbon Nanotubes (CNTs), especially single walled CNTs (SWNTS) have attracted interest for a wide range of technological applications because of their novel mechanical, electrical, optical properties. Synthesizing high yield, high purity, and monodispersed chiral SWCNTs is critical to exploit these properties to their full extent. A common route for CNT synthesis is catalytic chemical vapor deposition (C-CVD), which involves metal catalyst (i.e. Ni, Fe, Co) to decompose carbon precursors and to provide a nucleation site for SWCNTs formation. Researchers have achieved super growth of very long and pure SWCNT bundles . Only a few reports on monodispersed SWCNT of same chirality are available. Co/MgO is one of the catalyst-support systems that selectively grow mainly semiconductor SWCNT . Yet, the exact relationship between the tube growth and the catalyst-support system is still missing. We have employed an Environmental Scanning Transmission Electron Microscope (ESTEM) operated at 300 kV, which permits us to introduce C2H2 over the Co/MgO system at reaction temperatures and record real-time atomic resolution videos to capture nanotube cap nucleation, lift-off, and growth. We observed that the catalysts remained faceted during the whole process. The caps nucleated at the junction of two different facets of the catalyst. The caps grew laterally from the nucleation site and stopped growing larger when the cap rims reached another facet edge on the catalyst. The final cap geometry comprises a graphene sheet that is attached to epitaxially well-matched facets but that has lifted off from the mismatched facets. The cap then guides the subsequent growth of the SWCNT. In addition to the metal-graphene interfacial energies, other factors, such as a preferential adsorption of carbon at low-coordination metal sites, higher diffusion rates on specific metal surfaces or subsurfaces, are involved in SWCNT nucleation and growth. Therefore, we hypothesize that tuning the orientation and size of the catalyst particle facets can significantly improve chiral selection of SWCNTs. More details of the mechanism of SWCNT nucleation and growth, and chirality control will be presented.
1. Hata et al., Science 2004, 306, 1362
2. He et al., Nature Science Report, 2013, 3, 1460
3:45 AM - MM2.04
Carbon-Metal Interfaces Analysed by TEM: How Copper and Nickel Contact to MWCNTs and Graphite
Gabriele Ilari 1 2 Darius Pohl 3 Anja Bonatto Minella 3 Yucheng Zhang 1 Marco Cantoni 4 Fabienne Bobard 4 Niklaus Kraenzlin 2 Markus Niederberger 2 Rolf Erni 1
1Empa Damp;#252;bendorf Switzerland2ETH Zamp;#252;rich Switzerland3IFW Dresden Germany4EPFL Lausanne SwitzerlandShow Abstract
Because of their extraordinary electrical and thermal conductance graphite and more in general graphitic nanomaterials, such as carbon nanotubes (CNTs) or graphene, are discussed for various applications, one example being electrical conductors. For many applications it is necessary to contact them with a metal. Copper and nickel are metals used in electronic devices and are also interesting because of their different valence electron occupancy. The contact between copper/nickel and CNTs shows a contact resistance and is currently not well understood . This work emends the knowledge about these interfaces. Samples with copper and nickel interfaces towards MWCNTs and graphite were analysed. The comparison of the multiwalled CNT (MWCNT) metal interfaces with the ones of graphite points out the effect of the bent graphite layers in the CNTs.
An interfacial nickel carbide layer at the nickel-graphite interface could be observed by core-loss electron energy loss spectroscopy (EELS). Carbide formation at the copper-graphite interface was not observed by monochromated valence electron energy loss spectroscopy (VEELS) and core-loss EELS. The different behaviour of nickel and copper can be explained by the full valence d-shell of copper, which prevents it from covalent bonding without changing its electron configuration. Disturbances of the graphitic system could be detected by high resolution transmission electron microscopy (HRTEM) images. Those results from the graphite interfaces are compared with the ones from the MWCNT-metal samples.
 Lim S. C., et al. Appl Phys Lett, 95, 264103-264103-3 (2009).
MM3: Theoretical Investigation
Yoke Khin Yap
Tuesday PM, April 22, 2014
Moscone West, Level 2, Room 2006
4:30 AM - *MM3.01
Simulation of Charge Transport in Disordered Assemblies of Metallic Nano-Islands: Application to Boron Nitride Nanotubes Functionalized with Gold Quantum Dots (QDs-BNNTs)
John A Jaszczak 1 Madhusudan A. Savaikar 1 Banyai R. Banyai 1 Boyi Hao 1 Zhang Dongyan 1 Paul L. Bergstrom 2 An-Ping Li 3 Juan-Carlos Idrobo 4 Yoke Khin Yap 1
1Michigan Technological University Houghton USA2Michigan Technological University Houghton USA3Oak Ridge National Laboratory Oak Ridge USA4Oak Ridge National Laboratory Oak Ridge USAShow Abstract
In this study, we investigate the charge transport behavior in a disordered one-dimensional (1D) chain of metallic islands using the newly developed multi-island transport simulator based on semi-classical tunneling theory and kinetic Monte Carlo simulation . The 1D chain is parameterized to model experimentally-realized devices consisting of randomly sized gold nanometer-sized islands deposited on an insulating boron nitride nanotube . The effects of disorder, device length, temperature and source-drain bias voltage (VSD) on the current are examined. Preliminary results of random assemblies of gold nano-islands in two dimensions (2D) are also examined in light of the 1D results.
At T = 0 K and low bias the disordered 1D chain shows charge transport characteristics with a well-defined Coulomb blockade (CB) and Coulomb staircase (CS) features that are manifestations of the nanometer size of the islands. In agreement with the experimental observations, the CB and the blockade threshold voltage (Vth) at which the device begins to conduct increases linearly with increasing chain length. The CS structures are more pronounced in longer chains, but disappear at high VSD. Due to tunneling barrier suppression at high bias, the current-voltage characteristics follow a non-linear behavior. Smaller islands have a dominant effect on the CB and Vth, while wider junctions with their large tunneling resistances predominantly determine the overall device current. The study indicates that smaller islands with smaller inter-island spacings are better suited for practical applications. Temperature has minimal effects on high-bias current behavior, but the CB is diminished as Vth decreases with increasing temperature.
In 2D systems with sufficient disorder, our studies demonstrate the existence of a dominant conducting path (DCP) through which most of the current is carried, making the device effectively quasi-1-dimensional. The existence of a DCP is sensitive to the device structure, but can be robust with respect to changes in VSD.
Acknowledgements: Simulation studies were performed in part using the computing cluster wigner.research.mtu.edu in Information Technology Services and rama.phy.mtu.edu in the Department of Physics at Michigan Technological University. Y. K. Yap acknowledges the support from the U.S. Department of Energy, the Office of Basic Energy Sciences (Grant DE-FG02-06ER46294, PI:Y.K.Y.), the Center for Nanophase Materials Sciences at Oak Ridge National Laboratory (CNMS at ORNL) (Projects CNMS2009-213 and CNMS2012-083, PI:Y.K.Y.), and the ORNL&’s Shared Research Equipment (ShaRE) User Program (JCI).
. Savaikar et al., J. Appl. Phys. 114, 114504 (2013).
. Lee et al., Advanced Materials 25, 4544 (2013).
5:00 AM - *MM3.02
Controlling Atomic Movement on the Nanoscale
Sinisa Coh 1 2 Will Gannett 1 2 Alex Zettl 1 2 Marvin L. Cohen 1 2 Steven G. Louie 1 2
1UC Berkeley Berkeley USA2Lawrence Berkeley National Laboratory Berkeley USAShow Abstract
Some of the grand challenges in nanoscience are the ability to control movement of atoms either to propel nanometer-sized machines, or to synthesize novel electronic devices and materials. To that end, electrical current can be used to move a wide range of metals along a carbon nanotube (Fe, Cu, W, In, Ga). In this talk I will present our finding of a peculiar way in which these metals move. For example, we find that an iron nanocrystal is able to pass through a constriction in the carbon nanotube with a smaller cross-sectional area than the nanocrystal itself. Remarkably, through in situ transmission electron imaging and diffraction, we find that, while passing through a constriction, the nanocrystal remains largely solid and crystalline and the carbon nanotube is unaffected. I will also discuss implications of this work on synthesis of nanocomposite materials, and on the stability of carbon-based electronic devices.
More details can be found in these publications:
Phys. Rev. Lett. 110, 185901 (2013)
Phys. Rev. B 88, 045424 (2013)
This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Computational resources have been provided by the DOE at Lawrence Berkeley National Laboratory's NERSC facility.
5:30 AM - MM3.03
Point Defects in Carbon Nanotubes: Ab Initio and Force-Fields Based Simulations
Jaap M.H. Kroes 1 Fabio Pietrucci 1 Alessandro Curioni 2 Wanda Andreoni 1
1amp;#201;cole Polytechnique Famp;#233;damp;#233;rale de Lausanne Lausanne Switzerland2IBM Research Zurich Ramp;#252;schlikon SwitzerlandShow Abstract
We present the results of an extended investigation of point defects in carbon nanotubes (CNTs) and their effects on mechanical and electronic properties. This study is based on large-scale calculations using density-functional theory (DFT) with exchange and correlation functionals of the GGA - including empirical corrections for van-der-Waals interactions - and of the hybrid type. We also carried out simulations using classical interatomic potentials: this has allowed us to obtain a critical comparison between the outcome of DFT and force-fields. The CNT models adopted have a range of sizes and chiralities. In particular, (i) our simulations of oxygen chemisorption have revealed a tendency to clustering and also the existence of kinetic traps (epoxide configurations), which explain scanning tunneling spectroscopy data ; (ii) the extension to oxygen isovalent species on CNTs and other graphitic surfaces has suggested a simple predictive model for the chemisorption pattern . Moreover, (iii) our analysis shows an intrinsic difficulty of available force-fields to account for the energetics of vacancies and adsorption site preferences. Additional results aiming at characterizing the interaction of nitrogen oxides (NOx) with the CNT surface will also be presented.
We acknowledge support from Nano-Tera.ch, a program of the Swiss Confederation, evaluated by the SNSF, and the Swiss National Supercomputing Centre (CSCS) under project ID 245.
 J. M. H. Kroes, F. Pietrucci, A. Curioni, R. Jaafar, O. Gröning and W. Andreoni, J. Phys. Chem. C 117, 1948 (2013)
 J. M. H. Kroes, F. Pietrucci, A. Curioni and W. Andreoni, (to be published)
5:45 AM - MM3.04
Electro-Thermal Analysis of Aligned Carbon Nanotube Field Effect Transistors
Man Prakash Gupta 1 Satish Kumar 1
1Georgia Institute of Technology Atlanta USAShow Abstract
Carbon nanotubes (CNTs) are considered to be a very promising material due to their exceptional thermal, electrical, optical and mechanical properties. Many studies have been performed in the past decade in an effort to explore and develop devices which could leverage the excellent properties of CNTs. Particularly, CNT network based thin film transistors (CN-TFTs) has been explored in great detail as they may find applications in flexible displays, sensors, e-clothing, antennas, etc. In addition, recent advances in synthesis, purification and assembly of CNTs have also underscored the importance of CNT arrays or densely aligned CNTs based TFTs for high performance logic devices [1, 2]. Fewer studies have focused on (self-heating) thermal considerations of these devices which is an important aspect since CNTs are typically deposited on thermally insulating substrates. We have previously investigated the heat dissipation issues and associated thermal reliability in CNT random network based TFTs [3, 4]. In this work, we aim to investigate the performance and thermal reliability issues of perfectly aligned or semi-aligned CNTs based TFTs; we will consider the dense arrays of CNTs where CNT-CNT interaction is greatly pronounced and have not been appropriately simulated in the previous studies . This interaction can not only significantly affect the electrical performance but can also lead to thermal reliability problems. We plan to develop and employ a self-consistent electro-thermal model to understand the transfer characteristics of CN-TFTs along with the potential heat dissipation issues which could affect the device performance. Our electro-thermal model has been successfully used to explain experimental observations and to provide useful insights for design and optimization of CNT random network based TFTs. The present work will help in bridging the gap between electrical and thermal transport and reliability aspects of aligned/semi-aligned CN-TFTs.
 Shulaker, M.M.; Hills, G.; Patil, N.; Wei, H.; Chen, H.Y.; PhilipWong, H.S.; Mitra, S. Carbon nanotube computer. Nature 2013, 501, 526-530.
 Cao, Q.; Han, S.J.; Tulevski, G.S.; Zhu, Y.; Lu, D.D.; Haensch, W. Arrays of single-walled carbon nanotubes with full surface coverage for high-performance electronics. Nat Nanotechnol 2013, 8, 180-186.
 Gupta, M.P.; Behnam, A.; Lian, F.F.; Estrada, D.; Pop, E.; Kumar, S. High field breakdown characteristics of carbon nanotube thin film transistors. Nanotechnology 2013, 24.
 Gupta, M.P.; Chen, L.; Estrada, D.; Behnam, A.; Pop, E.; Kumar, S. Impact of thermal boundary conductances on power dissipation and electrical breakdown of carbon nanotube network transistors. J Appl Phys 2012, 112.
 Shekhar, S.; Erementchouk, M.; Leuenberger, M.N.; Khondaker, S.I. Correlated electrical breakdown in arrays of high density aligned carbon nanotubes. Appl Phys Lett 2011, 98.
MM4: Poster Session I
Yoke Khin Yap
Tuesday PM, April 22, 2014
Marriott Marquis, Yerba Buena Level, Salons 8-9
9:00 AM - MM4.01
Polyfluorenes for Selective Wrapping of Single-Walled Carbon Nanotubes
Martin Fritsch 1 Nils Froehlich 1 Sybille Allard 1 Ullrich Scherf 1 Maria Antonietta Loi 2 Widianta Gomulya 2 Satria Bisri 2 Vladimir Derenskyi 2 Guadalupe Damp;#237;az Costanzo 2
1Bergische University of Wuppertal Wuppertal Germany2University of Groningen Groningen NetherlandsShow Abstract
One defining characteristic of nanomaterials is that their properties often vary as a function of shape and size. For single-walled carbon nanotubes (SWCNT) such variations modify the electronic and optical properties mainly in a discontinuous manner. Metallic character can switch into semiconducting properties and vice versa. Since most technologies require predictable and uniform performance parameters, scientists have been intensively researching strategies for the preparation of SWCNTs with well-defined diameter, length, chirality, and electronic properties (uniform metallic, and especially uniform semiconducting nanotubes). The separation can be achieved by different methods including strategies borrowed from biochemistry (encapsulation by surfactants followed by ultracentrifugation or encapsulation with DNA) or in our case by spontaneous wrapping of conjugated polymers such as the fluorene-based homo- and co-polymers around SWCNTs with diameters around 1 nm.
The side chains of the conjugated polymer in these hybrid structures allow solubilization in common organic solvents. In previous reports, many different polymer structures have been tested with the ability to discriminate SWCNTs of different diameter and helicity on demand. PFO (poly(9,9-dioctylfluorene-2,7-diyl) has been demonstrated to be the a very efficient polymer for separation of SWCNTs with small diameters (0.8 - 1.2 nm). Earlier studies ascribed the discrimination mechanism to the nature of the polymer backbone. Recent research showed indications, that the side chain of the polymers also plays an important role in the wrapping and selection mechanism.
Within this report we demonstrate the selection of semiconducting SWCNTs in a wider diameter range (0.8 - 1.6 nm) using polyfluorene derivates with alkyl chains of increasing length (hexyl to octadecyl side chains). By tuning the length of the alkyl side chains SWCNTs of different diameter can be selected. SWCNTs with diameters > 1.2 nm, for whom post-synthetic separation methods did not exist up to date, can now be selected efficiently. The high amount of semiconducting SWCNTs in the prepared dispersions, which is extremely important for applications, is demonstrated by optical spectroscopy and by fabrication of high performing field-effect transistors with mobilities up to 14 cm2V-1s-1 for holes and 16 cm2V-1s-1 for electrons (on/off ratio: 105).
 Marc C. Herasm, Nat. Nanotech. 2008, 3, 387
 W. Gomulya, G. D. Constanzo, E. J. Figueiredo de Carvalho, S. Z. Bisri, V. Derenskyi, M. Fritsch, N. Fröhlich, S. Allard, P. Gordiichuk, A. Herrmann, S. J. Marrink, M. C. dos Santos, U. Scherf, M. A. Loi, Adv. Mat. 2013, 25, 2948
9:00 AM - MM4.03
Evidence for Solid-Like Hydrogen in Nanoporous Hydrogen Storage Materials
Valeska P. Ting 1 Anibal Ramirez-Cuesta 2 Nuno Bimbo 1 Jessica Sharpe 1 Tim J Mays 1
1University of Bath Bath United Kingdom2Oak Ridge National Laboratory Oak Ridge USAShow Abstract
As a sustainable, non-polluting alternative to fossil fuels, hydrogen has many benefits: it can be produced from water using a variety of renewable sources such as wind and solar power and when used in fuel cells or internal combustion engines, the only by-product is the regeneration of water. The critical barrier to the widespread use of hydrogen as a fuel is that it is a gas at room temperatures and pressures and so is challenging to efficiently and economically store and transport.
One heavily researched method of storing hydrogen is using nanoporous materials (materials with pore dimensions on angstrom or nanometre length scales, such as zeolites, metal-organic frameworks and nanostructured carbons), which can act as “molecular sponges” for adsorptive storage of hydrogen. The evaluation of the capacities of different porous hydrogen storage materials is generally based on modelling experimental gas adsorption isotherms using assumptions about the density of the hydrogen inside the pores. As this density is very difficult to experimentally determine, it is generally assumed that the maximum or limiting amount that can be stored in a porous material occurs when the density of the hydrogen in the pores reaches liquid-like densities.
However, our recent models and inelastic neutron scattering experiments have shown that in certain carbon nanomaterials containing optimally-sized pores, the adsorbed hydrogen inside the pores can be compressed to the point where it behaves as solid hydrogen under relatively mild conditions of temperature and pressure - where classically, this should not be possible. This new description of the density of hydrogen inside the pores has led to improvements in the ways in which hydrogen capacities can be modelled and predicted to allow more accurate comparisons of the maximum capacities of different nanoporous hydrogen storage materials. This will ultimately inform the design and development of new materials for on-board hydrogen storage solutions for transportation applications.
9:00 AM - MM4.05
Photocatalysis of Nano-Magnetite with Rod and Tube Morphologies
Yen-Hua Chen 1
1National Cheng Kung University Tainan City TaiwanShow Abstract
Recently, environmental topics have become more imperative. Photocatalysis is an environmentally friendly procedures that uses irradiation energy to perform catalytic reactions. Therefore, photocatalysis has been widely applicated for pollutant eradication. The magnetite is a common mineral in the nature and it has great potential to be used as photocatalysts under visible-light irradiation.
In this study, nano-magnetites with crystal morphologies of rods and tubes are synthesized via the nano-hematites with carbon reduction method. The magnetite nano-rod is fabricated with glucose/sample=1/6 at 5000C for 4 hrs, while magnetite nano-tube is synthesized with glucose/sample=1/12 at 5000C for 4 hrs. The specific surface area of nano-rod and nano-tube is 21.4 and 25.3 m2/g, respectively. The efficiency of photocatalytic degradation on M.B. is 88% for nano-rod and 90% for nano-tube within the first 510 mins. Moreover, the photocatalytic rate constant is 0.0042 and 0.0044 1/min for nano-rod and nano-tube, respectively, which increases with an increase of surface area. The results show that the photocatalytic activity of nano-magnetite is influenced by its crystal morphology. In addition, the photocatalytic ability of nano-magnetites is comparable with the literatures. This suggests that the nano-magnetite is the potential candidate in the application of the environmental remediation.
9:00 AM - MM4.06
Formation of Helical Silica Nanotube Using Binary Gelators
Jongwook Kim 1 Doyeon Kim 1 Jongsung Jin 1
1Korea Basic Science Institute Busan Republic of KoreaShow Abstract
Recently, many researchers have been interested in the self-assembled 3D supramolecular structures to synthesis of helical silica nanotubes. And the use of organic compounds as templates for the generation of inorganic structures and materials has received increasing attention over the last decade.
We have been studied the solvent-effects on the synthesizing of helical silica nanotubes via polycondensation of tetraethoxysilane (TEOS) on self-assembled structures that were composed 1,2-diphenylethylenediamine based neutral (G1) and cationic (G1N) gelators. By controlling parameters such as ratios of each gelator or the concentration of the reactants, we could finely fabricate the helical silica nanotubes.
In this study, we synthesized helical silica nanotubes by self assembly of organic gelators that prepared by heating a mixture of G1 and G1N using sol-gel condensation protocol with TEOS. The sol-gel reactions were carried out in ethanol solvent. And then, triethoxyoctylsilane was used to derivatized on the surface of nanotubes. The morphological structure of nanotubes was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The TEM images taken after remove the gelator. In order to confirm the reaction of silica nanotube fabrication, the nanotubes were analyzed using elemental analyzer, LC, HPLC and TOF-SIMS.
This work was supported by the grant No. R0001026 from the Ministry of Trade, Industry & Energy and Busan Metropolitan City, Korea.
9:00 AM - MM4.07
Solvent-Free Covalent Functionalization of Carbon Nanomaterials with Amino-Crown Ethers
Laura Veronica Henao-Holguin 1 Victor Meza-Laguna 2 Taras Gromovoy 3 Elena Basiuk 4 Vladimir Basiuk 5
1Universidad Nacional Autamp;#243;noma de Mamp;#233;xico Mamp;#233;xico D.F Mexico2Universidad Nacional Autamp;#243;noma de Mamp;#233;xico Mamp;#233;xico D.F Mexico3National Academy of Sciences of Ukraine Kiev Ukraine4Universidad Nacional Autamp;#243;noma de Mamp;#233;xico Mamp;#233;xico D.F Mexico5Universidad Nacional Autamp;#243;noma de Mamp;#233;xico Mamp;#233;xico D.F MexicoShow Abstract
The attachment (both covalent and noncovalent) of crown ethers and other heteromacrocyclic compounds to carbon nanostructures such as fullerenes and carbon nanotubes is studied in context of the design of supramolecular donor-acceptor systems to approach artificial photosynthesis. As a rule, the covalent attachment has obvious advantages due to superior bonding strength. On the other hand, the functionalization methodologies explored up to now include several derivatization steps, and thus are labor-consuming, as well as require large amounts of solvents and a number of auxiliary operations. The main goal of our work was to test the feasibility of simple, one-step and solvent-free covalent functionalization of pristine MWNTs and oxidized SWNTs, ND and fullerene C60 with amino-substituted crown ethers, namely, 4prime;-aminobenzo-15-crown-5 and 4prime;-aminobenzo-18-crown-6. The functionalization was carried out by preparing 1:1 (w/w) mixture of the carbon nanomaterial and amino-crown ether under vacuum and heated during 4 h at 160-170 C. The covalent attachment technique proposed is based on thermal instead of chemical activation. It is fast, does not require the use of organic solvent reaction medium and auxiliary operations (washing, centrifugation, drying, etc.), and therefore can be considered as ecologically friendly. The specific covalent bonding mechanism depends on carbon nanomaterial employed. It relies on the formation of amide bo