Nanomosis

Electrolytes in Nanopores: Molecular Simulations and Related Applications

Kwong-Yu Chan, Professor in the Department of Chemistry, the University of Hong Kong, presented the following seminar at the Pacific Rim Conference in Nanoscience (7-11 September 2004). The seminar is available for viewing and discussion through the internanotech Community at http://internanotech.net/

Electrolytes in Nanopores: Molecular Simulations and Related Applications

Before presenting molecular simulations of electrolytes confined in nanopores, an overview and examples will be given for applications and experiments related to transport of electrolytes in nanostructures. The operation of a small room temperature liquid fuel cell will be demonstrated. The modification of the nanopores of Nafion, a solid polymer electrolyte, to change its proton, water and methanol permeability will be reported. Improvement of the membrane performance in a methanol fuel cell is probably due to the change of hydrophobicity of furfuryl alcohol during its polymerization within the nanopores of the membrane. Syntheses of porous carbon electrode materials with long and well-defined mesopores will be presented. The loading of mixed metal nanoparticles into these structures and the electrochemical performance will also be discussed as an example of the applications of nanostructured electrodes.

Equilibrium and non-equilibrium molecular dynamics simulations (EMD & NEMD) are applied to several models of electrolytes, including the extended simple point charge (SPC/E) model for water. Confinement by the nanopore affects the solvation of ions, hydrogen bonding, ion-ion interaction, and the mobility of ions and water. The presence of an external field in NEMD allows the direct observation of a current and net flow of ions. Comparisons of the EMD and NEMD results are made and the validity of the Nernst-Einstein relation is discussed. In addition, the application of an alternating electric field allows investigations of frequency dependent conductivity and relaxation phenomena. In the narrowest channel, severe confinement leads to more ion pairing, less solvation, less hydrogen bonding, and also a capacitor character.



Barry Hardy
Douglas Connect
www.douglasconnect.com
internanotech Community: internanotech.net
Blog On Nanotechnology - Nanomosis: http://barryhardy.blogs.com/nanomosis/

InterNanotech 2005: International Conference in Experimental & Computational Nanoscience

Conference Topics: Nanofluidics, nanobiology, nanofabrication, nanoparticles, computational nanoscience, nanomaterials, nanotubes, nanodevices, nanoelectronics, molecular manufacturing, activated carbon and zeolite design, self-assembly, health, safety, environmental and medical applications.

This community project is an international, interdisciplinary community for scientists working in research areas of relevance to nanoscience and nanotechnology.

The activities of the community support the rapid exchange of new research results and discussion in experimental and computational nanoscience. Members can attend regular Virtual Seminar sessions to keep up with research news and results from leading experts in the field.

Oversight, advice and guidance of the scientific program is provided by a Scientific Advisory Board, chaired by Prof. Nick Quirke of Imperial College London.

Web- and phone- based Conference sessions will be held monthly in Spring and Autumn 2005.

Call for Seminars/Papers: Please submit a short summary proposal for a proposed session you would be interested in chairing (ca. 500 words) or for a talk you would wish to present (ca. 300 words) to nanotech [at] douglasconnect.com by 31 October 2004.

All papers will be considered for publication in Molecular Simulation and the forthcoming Journal of Experimental Nanoscience (first issue, January 2006).

Please complete the Sign-Up on the Internanotech Web site at http://nanotech.colayer.net/ to stay informed.

Barry Hardy
Douglas Connect
www.douglasconnect.com

New International Nanotech Community Launches

Zeiningen (Switzerland), September 7, 2004: Douglas Connect announces the launch of InterNanotech, a new online community for international researchers in computational and experimental nanoscience and nanotechnology. By holding regular seminar sessions over the internet, supported by virtual communication and networking tools, InterNanotech is designed to facilitate rapid communication of new research results and discoveries between different disciplines and geographic regions.

The scientific advisory board is headed by Prof. Nick Quirke of Imperial College, London, who emphasized “Nanotech is such a large field, encompassing most if not all scientific disciplines, that it is vital to have a forum in which it is possible to make new contacts easily and exchange information and news as rapidly as possible. I think the concept of the InterNanotech community will make a vital contribution to this end.” Dr Jurgen Schulte, Executive Director of the Asia Pacific Nanotechnology Forum went on to say, “A vibrant manufacturing industry depends on its ability to adapt swiftly to a changing market and its long term viability and future depends on its ability to pro-actively engage in innovation. Nanotechnology is about to become one of the key driving forces in a new cycle of innovation in Asia and around the world.”

Prof. Quirke and Dr Schulte were speaking from Broome, Australia where they are currently at the Pacific Rim Conference in Nanoscience, which starts today and is being chaired by Prof. Quirke. InterNanotech’s first activity is to make this conference available over the internet, not only as an online record for the participants during and after the conference, but also for all the people who were unable to attend in person. Presentations will be recorded and uploaded daily, along with the accompanying presentation materials. The conference includes contributions from leading researchers in the Pacific Region, in addition to invited speakers from Europe and the USA, and contains a significant amount of advanced chemistry and physics applied to nanotech research problems. InterNanotech is also giving a talented young scientist from India, Dr B.L.V. Prasad of the National Chemical Laboratory Nanoscience Group, a unique opportunity to present his work on the synthesis of metal magnetic nanoparticles. “I was overjoyed when my abstract was accepted for a hot-spot lecture at the conference in Australia, but I wasn’t able to raise the funds to travel there,” said Dr Prasad, who continued “I cannot express how thrilled I was when I learned that I would still be able to hear the lectures through the virtual conference, and I could also present my work to an international audience from right here in India. I really hope this concept picks up! ”

Later in the year, members of the InterNanotech community will also be able to join a session on Modelling of Membranes and Ion Channels, chaired by Dr Richard Pastor of the FDA Center for Biologics Evaluation & Research. InterNanotech will continue throughout 2005 with regular seminar sessions covering topics related to nanofluidics, nanobiology, nanofabrication, nanoparticles, computational nanoscience, nanomaterials, nanodevices, nanoelectronics, molecular manufacturing, activated carbon and zeolite design, self-assembly, health, safety, environmental and medical applications.

Full information about the Conference and the Community can be found on http://nanotech.colayer.net
Contact: Nicki Douglas, nanotech (at) douglasconnect.com, Tel: +41 61 851 04 61

Douglas Connect (www.douglasconnect.com)
Douglas Connect organises both independent and sponsored virtual conferences for scientific communities, as well as providing consultancy services for setting up communities of expertise and for a range of communication projects. Further current conferences by Douglas Connect include eCheminformatics: Applications of Cheminformatics and Chemical Modelling to Drug Discovery; and eCombiChem: Cutting Edge Technologies in Combinatorial Chemistry; and Integrating Knowledge in the Life Science Product Life Cycle. Douglas Connect is based in Zeiningen, Switzerland.

Functional Interfaces and Nanostructures

Terry Turney, Director of CSIRO's Nanotechnology Centre and Science Director for New Materials within its Manufacturing division, will present the following seminar from the Pacific Rim Conference in Nanoscience (7-11 September 2004). The seminar will be available for viewing and discussion through the internanotech Community at http://nanotech.colayer.net/

Functional Interfaces and Nanostructures

The study, design and control of interfacial phenomena are just as important to the application of nanotechnology for practical outcomes as they are to its scientific understanding. This talk will examine the properties of tailored nanoparticles and their effect on nanocomposite properties.

Nanoparticles of ZnO exhibit a correlation between particle size and photochemical activity, with controlled doping allowing the modification of both photochemical and biological activity. A range of nanocomposites, produced by nanoparticle dispersion into polymers, has found application in UV-resistant composites, nucleating agents for polyolefins, coatings and gas barrier membranes.

Addition of nanoparticles to a polymer can selectively modify chain packing allowing hybrid membranes with increased diffusion coefficients and even selective passage of larger molecules through the membrane rather than smaller molecules. The interaction between the inorganic domains and the polymer chains is important to tuning these hybrid properties.


Barry Hardy
Douglas Connect
www.douglasconnect.com
internanotech Community: http://nanotech.colayer.net/
Blog On Nanotechnology - Nanomosis: http://barryhardy.blogs.com/nanomosis/

Water-catalyzed dehalogenation reactions: building a nanoscale water solvated reaction system one molecule at a time

Prof. David Phillips, Director of the Ultrafast Laser Facility at The University of Hong Kong, will present the following seminar from the Pacific Rim Conference in Nanoscience (7-11 September 2004). The seminar will be available for viewing and discussion through the internanotech Community at http://nanotech.colayer.net/

Water-catalyzed dehalogenation reactions: building a nanoscale water solvated reaction system one molecule at a time

Bromoform is the most abundant source of organic bromine in the ocean and atmosphere and this makes it an attractive polyhalomethane to study.[1] Ultraviolet excitation with 253.7 nm light (from a Hg lamp) of low concentrations (<10-6 M) of CHBr3 , CHBr2Cl, and CHCl2Br in aqueous solution led to complete conversion of the halogens into halide ions (bromide and/or chloride) with similar photo-quantum yields of about 0.43.[2] How does the 253.7 nm photolysis of low concentrations of CHBr3 , CHBr2Cl, and CHCl2Br in water lead to complete conversion of the halogen atoms into bromide and/or chloride ion products and where does the energy come from to break all three carbon-halogen bonds?

We present a combined experimental and theoretical study of the photochemistry of CHBr3 in pure water and in acetonitrile/water mixed solvents that elucidates the reactions and mechanisms responsible for the photochemical conversion of the halogen atoms in CHBr3 into three bromide ions in water solution. Photochemistry experiments show 240 nm excitation of CHBr3 (about 9 x10 -5 M) in water leads to almost complete conversion into 3HBr leaving groups and CO (major product) and HCOOH (minor product) molecules. Picosecond time-resolved resonance Raman (ps-TR3 ) experiments and ab initio calculations indicate that water catalyzed O-H insertion/HBr elimination reaction of isobromoform and subsequent reactions of its products are responsible for the formation of the final products observed in the photochemistry experiments reported here.

Ab initio calculations (MP2/6-31G*) were done to study the isobromoform + nH2O->CHBr2OH + HBr + (n-1)H2O where n= 1,2,3; CHBr2 OH + nH2O->HBrCO + HBr + nH2O where n=0,1,2,3 and HBrCO + nH2O->CO + HBr + nH 2 O where n=0,1,2,3,4 reactions. IRC calculations were done to confirm the transition states connected the appropriate reactants and products. The relative energy profiles (in kcal/mol) for the reactions reveal that the barriers to reaction (e.g. from the reactant complexes to their respective transition state) become substantially smaller as the number of H2O molecules in the reaction system increase. This indicates water catalyzes these reactions. The reaction barrier decreases from 10.8 kcal/mol for one H2O molecule to 2.5 kcal/mol for three H2O molecules for the isobromoform + nH2O->CHBr2OH + HBr + (n-1)H2O reaction; from 17.6 kcal/mol for one H2O molecule to 2.25 kcal/mol for three H2O molecules for the CHBr2OH + nH2O->HBrCO + HBr + nH2O reaction and from 17.8 kcal/mol for one H2O molecule to 8.6 kcal/mol for three H2O molecules for the HBrCO + nH2O->CO + HBr + nH2O reaction. These results have important ramifications for the phase dependent behavior of polyhalomethane photochemistry and chemistry in water-solvated environments compared to gas phase reactions. A brief discussion is given for how this phase dependent behavior may influence the release and activation of halogens from polyhalomethanes in the natural environment. The solvation of the HBr leaving group and its spontaneous dissociation reaction into H+ and Br- ions helps catalyze several O-H insertion and HBr elimination reactions that also enable O-H and C-H bonds to be easily broken.[3] This water-catalysis by solvation of a leaving group and its spontaneous dissociation into ions (e.g. H+ and Br- in the example studied here) should be of general interest for a wide range of chemical reactions occurring in water environments including some biological reactions.

References
[1] Wayne, R. P. Chemistry of Atmospheres , Oxford University Press, 2000, 3 rd Ed. Oxford, U. K.
[2] I. Nicole, J. de Laat, M. Dore, J. P. Duguet, H. Suty, Environ. Technol. 12, ( 1991 ) 21-31.
[3] W. M. Kwok, C. Zhao, Y.-L. Li, X. Guan, and D. L. Phillips, J. Am. Chem. Soc. 126 ( 2004 ) 3119-3132.

Barry Hardy
Douglas Connect
www.douglasconnect.com
internanotech Community: http://nanotech.colayer.net/
Blog On Nanotechnology - Nanomosis: http://barryhardy.blogs.com/nanomosis/

Nanofluidics: Molecularly thin lubricant layers under confinement

Thomas Becker, University of Ulm, Germany, will present the following seminar from the Pacific Rim Conference in Nanoscience (7-11 September 2004). The seminar will be available for viewing and discussion through the internanotech Community at http://nanotech.colayer.net/

Nanofluidics: Molecularly thin lubricant layers under confinement

Confined liquid films with a thickness in the range of a few molecular diameters exhibit different mechanical properties than in the bulk. With the technique of a 2-dimensional imaging Surface Force Apparatus we investigated in detail the layer by layer thinning of a confined thin liquid film with increasing external normal force on the substrates. The dynamics of the boundary line of the layering transitions were analyzed and we found good agreement with a simple hydrodynamic model. While it is generally accepted that the viscosity of confined liquids increases with decreasing thickness, the order of magnitude is highly debated. Using ultraclean, recleaved mica surfaces in our measurements, we find that the viscosity of the model lubricant Octamethylcyclotetrasiloxane (OMCTS) increases by a factor of 10 with decreasing the film thickness from 6 to 2 layers. Using a new hydrodynamic model, we show that the sliding friction of liquid layers on top of the solid substrates is approximately 30 times higher than the mutual friction between adjacent liquid layers. The latter was independent of film thickness and in close agreement with the bulk viscosity. The mentioned variations in mechanical properties of thin liquid films compared with the bulk arise from structural changes. Making use of recent advances in synchrotron radiation sources and beam shaping techniques allow scattering experiments to investigate the in-plane structure of confined liquids. We present here preliminary x-ray scattering data from a thin film of confined liquid crystalline 8CB and we discuss the domain structure of the liquid crystal and the anchoring of the liquid crystal with respect to the mica lattice.

Barry Hardy
Douglas Connect
www.douglasconnect.com
internanotech Community: http://nanotech.colayer.net/
Blog On Nanotechnology - Nanomosis: http://barryhardy.blogs.com/nanomosis/