| Nanotubule Membranes - Fundamentals and Applications in Electrochemical Energy and Stochastic Sensing |
14 NOV 2002 |
5 pages |
| Authors:
Charles R. Martin; FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
|
 | The objectives are: (1) To develop the measurement technology that will allow us to determine if the a-hemolysin channel has been successfully immobilized, (2) To develop ultrathin film channel immobilization technology, and (3) To develop methods for isolating a single nanotubule in an Au nanotubule membrane For the Electrochemistry Division the objectives are (1) To develop new classes of nanotubule membranes whose transport properties can be modulated electrochemically by applying ... |
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| Imidazole and Its Derivatives as Inhibitors for Prevention of Corrosion of Copper |
01 JUN 1999 |
34 pages |
| Authors:
R. Gasparac; E. Stupnisek-Lisac; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| The aim of this work was to investigate the efficiency of imidazole and its derivatives 4-methylimidazole, 4-methyl-5-hydroxymethylimidazole, 1- phenyl-4-methylimidazole, 1-(p-tolyl)-4-methylimidazole for corrosion inhibition of copper in 0.5M hydrochloric acid. Corrosion inhibition was studied using impedance spectroscopy and potentiodynamic methods. Results obtained from the AC impedance measurements are in good agreement with those obtained from d.c. polarization measurements. The copper samples were also analyzed by scanning electron microscopy (SEM) and X-rays ... |
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| Preparation of Polymeric Micro-and Nanostructures Using a Template-Based Deposition Method |
01 JUN 1999 |
19 pages |
| Authors:
Veronica M. Cepak; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Polymeric microtubules and nanofibrils have been prepared by depositing a solution of the desired polymer within the pores of microporous template membranes. Both microporous alumina and track-etched polyester membranes were used as the templates. Tubules and fibrils composed of polystyrene, poly(2,6-dimethyl-1,4-phenylene oxide), poly(vinylidene fluoride), poly(methyl methacrylate), poly(bisphenol A carbonate), and poly(lactic acid) have been prepared. Nanofibrils with diameters as small as 30 nm have been achieved. A concentric tubular composite ... |
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| Using Template-Synthesized Micro- and Nanowires as Building Blocks for Self-Assembly of Supramolecular Architectures |
01 JUN 1999 |
14 pages |
| Authors:
Shawn A. Sapp; David T. Mitchell; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Template-synthesized conductive polymer microwires and Au nanowires have been used as building blocks to self-assemble supramolecular architectures. In the conductive polymer case, biotin/streptavidin chemistry was used to self- assembly latex spheres onto the ends of the conductive polymer microwires. In the Au case, thiol chemistry was used to self-assemble colloidal Au nanoparticles onto the ends of the Au nanowires. |
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| Sol-Gel-Based Template Synthesis and Li-Insertion Rate Performance of Nanostructured Vanadium Pentoxide |
01 JUN 1999 |
26 pages |
| Authors:
Charles J. Patrissi; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We have prepared nanostructured electrodes of orthohombic V205 using the template synthesis method. These electrodes were used to investigate the effects of Li-ion diffusion distance and surface area on V2O5 rate capability. Nanowires of V2O5 were prepared by depositing a precursor into the pores of microporous polycarbonate filtration membranes. This procedure yielded an ensemble of 115 nm diameter, 2 micrometers long nanowires of V2O5 which protruded from a V2O5 surface ... |
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| New Highly-Sensitive Methods for Electroanalytical Chemistry Based on Nanotubule Membranes |
01 JUN 1999 |
36 pages |
| Authors:
Yoshio Kobayashi; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Two new methods of electroanalysis are described. These methods are based on membranes containing monodisperse Au nanotubules with inside diameters approaching molecular dimensions (approx. 1 to approx. 3 nm). In one method the analyte species is detected by measuring the change in trans-membrane current when the analyte is added to the nanotubule-based cell. The second method entails the use of a concentration cell based on the nanotubule membrane. In this ... |
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| Template-Preparation and Characterization of Semiconductor Nanorod Organosols |
01 JUN 1999 |
24 pages |
| Authors:
Veronica M. Cepak; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| The template method was used to prepare organosols composed of either CdS nanords (diameter = 45 nm or 90 nm) or ZnO nanorods (diameter = 90 nm). Polycarbonate track-etched filters were used as the template membranes. After template synthesis, the nanorods were released from the template membrane and dispersed in chloroform. The stability of these nanorod organosols was monitored using UV-visible absorption spectroscopy. The 90 nm-diameter CdS nanorod organosols were ... |
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| An Electrochemically-Driven Actuator Based on a Nanostructured Carbon Material |
01 JUN 1999 |
27 pages |
| Authors:
Guangli Che; Scott A. Miller; Ellen R. Fisher; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| A new type of electrochemically-driven actuator is described. This actuator uses graphitic carbon as the electroactive material (as opposed to the polymeric films used in previous devices of this type), and it is the first example of an actuator based on a nanostructured material. The actuator consists of branched carbon nanotubules embedded within the pores of a microporous alumina template membrane. Electrochemical Li(+) intercalation causes this nanotubule-containing membrane to flex, ... |
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| New Developments in Membrane-Based Chemical Separations |
30 DEC 1998 |
15 pages |
| Authors:
Kshama B. Jirage; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Membrane based chemical separations is an emerging field of research. This is because membrane-based separations are potentially less energy intensive and more cost effective than competing separation methods. Polymeric membranes that contain a collection of monodisperse gold nanotubules with molecular dimensions were used to filter molecules based on their difference in size. Also, we will discuss how these tubules can be modified with thiols to separate ... |
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| Molecular Filtration in Nanotubule Membranes: Sorting Molecules on the Basis of Size and Chemistry |
30 DEC 1998 |
9 pages |
| Authors:
Kshama B. Jirage; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Membrane based chemical separations is an emerging field of research. This is because membrane-based separations are potentially less energy intensive and more cost effective than competing separation methods. Polymeric membranes that contain a collection of monodisperse gold nanotubules with molecular dimensions were used to filter molecules based on their difference in size. Also, we will discuss how these tubules can be modified with thiols to separate ... |
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| Template Synthesis of Bismuth Telluride Nanowires |
01 DEC 1998 |
15 pages |
| Authors:
Shawn A. Sapp; Brinda B. Lakshmi; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| We report the fabrication of thermoelectric bismuth telluride nanowires using the template synthesis method. A simple electrodeposition procedure was used to produce the nanowires within the pores of an alumina filtration membrane. The resulting bismuth telluride/alumina composite membranes constitute an array of thermoelectric nanowires surrounded by a thermally and electrically insulating matrix. The individual bismuth telluride nanowires can be isolated by removal of the template ... |
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| Preparation and Stability of Template-Synthesized Metal Nanorod Sols in Organic Solvents |
01 DEC 1998 |
30 pages |
| Authors:
VeVeronica M. Cepak; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Gold and silver nanorods of diameter 40 and 90 nm, and having a variety of aspect ratios (length/diameter), were prepared using the template synthesis approach. The stability of these nanorod sol was monitored using visible absorption spectroscopy. For both the Au and Ag nanorods (in both solvents), sols prepared from the 90 nm-diameter nanorods were found to be less stable than sols prepared from the ... |
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| Toward Colloidal Dispersions of Template Synthesized Polypyrrole Nanotubules |
01 JUL 1998 |
17 pages |
| Authors:
Silvia De Vito; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| A procedure for preparing colloidal dispersions of template- synthesized polypyrrole nanotubules is described. This procedure entails the use of an anionic surfactant as a dispersing agent, and slow dissolution of the template membrane is critical. Dispersion of nominally 200 nm and 50 nm diameter polypyrrole nanotubules have been prepared. |
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| Nanomaterials in Electrochemistry |
01 JUL 1998 |
73 pages |
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nanomaterials and electrochemistry have a long shared history, for example, the use of finely dispersed Pt particles as catalysts in fuel cell electrodes. This chapter, however, deals specifically with applications of template-synthesized nanomaterials in electrochemistry. We begin with an overview of template materials. Three possible electrochemical applications of such materials are then discussed. The first entails use of the template method for preparing ensembles of nanoscopic electrodes. The second application ... |
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| Introducing Chemical Transport Selectivity into Gold Nanotubule Membranes |
01 JUL 1998 |
16 pages |
| Authors:
John C. Hulteen; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We recently described polymeric membranes that contain a collection of monodisperse Au nanotubules with inside diameters of molecular dimensions (<1 nm). W showed that these membranes can be used to cleanly separate small molecules on the basis of molecular size. These membranes can also show charge- based transport selectivity which can be reversible switched between cation and anion-selective states. In addition to molecular size- and charge-based selectivity, chemical interactions (e.g., ... |
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| Template Synthesis of Nanoparticles in Nanoporous Membranes |
29 DEC 97 |
61 pages |
| Authors:
John C. Hulteen; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Many methods for the fabrication of nanoparticles have been developed ranging from lithographic techniques to chemical methods. This research group has been exploring a fabrication method termed template synthesis for the preparation of a variety micro- and nanomaterials. This process involves synthesizing a desired material within the pores of a porous membrane. Because the membranes that are used have cylindrical pores of uniform diameter, a nanocylinder of the desired material ... |
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| Ion Exchange Voltammetry at Polymer Film Coated Nanoelectrode Ensembles |
26 SEP 96 |
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| Authors:
Paolo Ugo; Ligia M. Moretto; Sara Bellomi; Vinod P. Menon; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
 | Ensembles of nanoscopic disk-shaped electrodes have been shown to offer enhancements in electroanalytical detection limits relative to electrodes of macroscopic dimensions (e.g., disk electrodes with diameters of ca. 1 mm). Enhancements in electroanalytical detection limits have also been observed at macroscopic electrodes that have been coated with films of ion exchange polymers. In this paper we combine these two concepts. We demonstrate that a nanoelectrode ensemble (NEE) that has been ... |
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| Anionically-Conductive Ultrathin Film Composite Membranes |
30 JUL 96 |
9 pages |
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We developed new approaches for preparing ultrathin film composite membranes based on the anionically/electronically conductive polymers that were of interest to this research effort. Of particular interest, we developed methods for coating microporous hollow fibers with thin films of such polymers. This is important because hollow fiber supports provide the highest active surface area per unit volume of any support material. High surface area insures high permeant (e.g., anion, molecule ... |
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| Membrane-Based Synthesis of Nanomaterials |
03 JUN 96 |
37 pages |
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| This article reviews a relatively new method for preparing nanomaterials - membrane-based synthesis. This method entails the synthesis of the desired material within the pores of a nanoporous membrane. Because the membranes employed contain cylindrical pores of uniform diameter, monodisperse nanocylinders of the desired material, whose dimensions can be carefully controlled, are obtained. These nanocylinders may be either hollow (a tubule) or solid (a fibril or nanowire). We call this ... |
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| Investigation of Molecular and Supermolecular Structure in Template- Synthesized Polypyrrole Tubules and Fibrils |
JUN 96 |
46 pages |
| Authors:
Vinod P. Menon; Junting Lei; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nanotubules and nanofibrils of polypyrrole were chemically synthesized using the pores of nanoporous polycarbonate membrane filters as templates. We have previously shown that such 'template-synthesized' nanofibrils of polypyrrole can have enhanced conductivities relative to more conventional forms of the polymer (e.g. thin films). Furthermore, we have shown that this enhancement in conductivity is critically dependent on the diameter of the nanofibrils; the narrowest diameter fibrils show the greatest enhancements in ... |
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| Template Preparation of Nanoelectrode Ensembles - Achieving the 'Pure- Radial' Electrochemical-Response Limiting Case |
JUN 96 |
21 pages |
| Authors:
John C. Hulteen; Vinod P. Menon; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We have been investigating a new method for preparing ensembles of disk-shaped nanoscopic electrodes. This method entails deposition of the electrode material into the pores of a nanoporous membrane. Nanoscopic wires of the electrode material, with monodisperse diameters, are obtained in each pore. The ends of these nanowires (at one face of the membrane) define the ensemble of disk-shaped nanoelectrodes. We call this approach for preparing nanoelectrode ensembles (NEEs) the ... |
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| Template Polymerization of Conductive Polymer Nanostructures |
23 APR 96 |
41 pages |
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nanochemistry is an emerging subdiscipline of the chemical and materials sciences that deals with the development of methods for synthesizing nanoscopic particles of a desired material and with scientific investigations of the nanomaterial obtained. Nanomaterials have numerous possible commercial and technological applications including use in electronic, optical and mechanical devices, drug delivery and bioencapsulation. In addition this field poses an important fundamental philosophical question--how do the properties (e.g., electronic, optical, ... |
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| Template Synthesis of Graphitic Nanotubules |
17 JUL 95 |
14 pages |
| Authors:
Ranjani V. Parthasarathy; K. L. Phani; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We describe a method for preparing monodisperse graphitic nanotubules. These are prepared by synthesizing polyacrylonitrile (PAN) from the monomer, within the pores of a porous alumina template membrane. Because the membrane used has cylindrical pores of uniform diameter, monodisperse PAN tubules are obtained. The PAN tubules are then heated to affect graphitization of the PAN. jg p.2 |
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| Fabrication and Evaluation of Nanoelectrode Ensembles |
18 APR 95 |
42 pages |
| Authors:
Vinod P. Menon; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| An electroless deposition procedure for filling the pores in nanoporous filtration membranes with metal (gold) nanowires is described. This method allows us to routinely prepare ensembles of gold nanodisk electrodes in which the nanodisks have diameters as small as 10 nm. Results of electrochemical experiments at ensembles of 30 nm-diameter and 10 nm-diameter gold-disk electrodes are described. The electrochemical response characteristics of these nanoelectrode ensembles are in agreement with predictions ... |
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| Polymeric Microcapsule Arrays |
24 MAR 95 |
10 pages |
| Authors:
Charles R. Martin; Ranjani V. Parthasarathy; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Immobilized enzymes are used in bioreactors and biosensors. Current methods for immobilizing enzymes include adsorption or covalent attachment to a support, microencapsulation and entrapment within a membrane/film or gel. The ideal enzyme immobilization method would (1) Employ mild chemical conditions; (2) Allow for large quantities of enzyme to be immobilized; (3) Provide a large surface area for enzyme/substrate contact within a small total volume; (4) Minimize barriers to mass transport ... |
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| Metal Nanotubule Membranes with Electrochemically Switchable Ion- Transport Selectivity |
MAR 95 |
20 pages |
| Authors:
Matsuhiko Nishizawa; Vinod P. Menon; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Membranes that contain cylindrical metal nanotubules that span the complete thickness of the membrane are described. The inside radius of the nanotubules can be varied at will; nanotubule radii as small as 0.8 nm are reported here. These metal nanotubule membranes show selective ion transport analogous to that observed in ion-exchange polymers. Ion permselectivity is observed because excess charge density can be present on the inner walls of the metal ... |
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| Enzyme and Chemical Encapsulation in Polymeric Microcapsules |
95 |
46 pages |
| Authors:
Ranjani V. Parthasarathy; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Polypyrrole microcapsules (prepared via the template method) were used for immobilization of both enzymatic and chemical catalytic systems. Enzymes immobilized include glucose oxidase, catalase, trypsin, subtilisin, and alcohol dehydrogenase. The chemical catalytic system investigated consisted of immobilized Pd nanoparticles for catalysis of hydrogen peroxide decomposition. Microcapsules loaded with glucose oxidase (GOD) were found to have higher enzymatic activity than GOD-loaded thin films, a competing encapsulation method. Trypsin was used to ... |
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| Nanomaterials--A Membrane-Based Synthetic Approach |
NOV 94 |
38 pages |
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nanomaterials constitute an emerging, interdisciplinary field of science that deals with the development of methods for preparing nanoscopic bits of a desired material (e.g. a polymer, metal, semiconductor) and with scientific investigations of the nanomaterials obtained. Nanomaterials have numerous possible commercial and technological applications. In addition, this field poses an important fundamental philosophical question--how do the properties of a nanoscopic bit of a material differ from the analogous properties for ... |
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| Template Synthesis of Electronically Conductive Polymer Nanostructures |
NOV 94 |
|
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nanochemistry is an emerging subdiscipline in the chemical and materials sciences that deals with the development of methods for synthesizing nanoscopic bits of a desired material and with chemical and other investigations of the nanomaterial obtained. My research group has been exploring a general method, called "template-synthesis," for preparing nanomaterials. This method entails synthesizing the desired material within the pores of a nanoporous membrane. The membranes employed have cylindrical pores ... |
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| Anionically-Conductive Ultrathin Film Composite Membranes |
19 AUG 94 |
8 pages |
| Authors:
Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| As noted in the previous technical report, we are interested in using interfacial polymerization to synthesize ultrathin film composite membranes based on electronically conductive polymers. During the previous year of AASERT funding we have expanded on this idea in a number of ways. We have done such interfacial polymerizations to make new composites for membrane-based separations, and to make novel coated-hollow fiber membranes. Ultrathin film composite membranes, Electrochemistry ion-transport ... |
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| Mechanism of the Amperometric Response of a Proposed Glucose Sensor Based on a Polypyrrole-Tubule-Impregnated Membrane |
MAY 94 |
29 pages |
| Authors:
Susumu Kuwabata; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nolte et al recently proposed a new type of amperometric glucose sensor. This sensor is based on a microporous membrane that contains polypyrrole tubules within the pores of the membrane. The procedure for preparing these polypyrrole tubules was developed in this laboratory. Nolte et al claim that glucose oxidase can be irreversible adsorbed to the inside walls of these polypyrrole tubules and that the resulting device functions as a glucose ... |
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| Synthesis of Polymeric Microcapsule Arrays and Their Use for Enzyme Immobilization |
APR 94 |
23 pages |
| Authors:
Ranjani Parthasarathy; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Immobilized enzymes are used in bioreactors and biosensors. Current methods for immobilizing enzymes include adsorption or covalent attachment to a support, microencapsulation and entrapment within a membrane/film or gel. The ideal enzyme immobilization method would (1) Employ mild chemical conditions; (2) Allow for large quantities of enzyme to be immobilized; (3) Provide a large surface area for enzyme/substrate contact within a small total volume; (4) Minimize barriers to mass transport ... |
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| Template Synthesized Nanoscopic Gold Particles: Optical Spectra and the Effects of Particle Size and Shape |
25 JAN 94 |
43 pages |
| Authors:
Colby A. Foss Jr.; Gabor L. Hornyak; Jon A. Stockert; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We have prepared nanoscopic gold cylinders of controlled radius and aspect ratio via electrodeposition of the metal within the pores of anodically- grown porous aluminum oxide membranes. The nanocylinder radii are determined by the pore dimensions of the host alumina which, in turn, depend on anodization conditions. The particle aspect ratios were controlled by varying the amount of Au deposited within the pores The optical spectra of the gold nanocylinder/ ... |
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| Biosensors Based on Ultrathin Film Composite Membranes |
25 JAN 94 |
22 pages |
| Authors:
Charles R. Martin; Barbara Ballarin; Charles J. Brumlik; Del R. Lawson; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| This paper introduces a new approach for designing chemical sensors. This approach is based on a concept borrowed from the membrane-based separations area -- ultrathin film composite membranes. Ultrathin film composite membranes consist of an ultrathin (less than ca. 100 nm-thick) polymer skin coated onto the surface of a microporous support membrane. These composite membranes have made a tremendous impact on the field of membrane-based separations because they can offer ... |
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| Template Synthesis of Metal Microtubule Ensembles Utilizing Chemical, Electrochemical, and Vacuum Deposition Techniques |
03 JAN 94 |
37 pages |
| Authors:
Charles J. Brumlik; Charles R. Martin; Vinod P. Menon; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Microtubules are an interesting type of microstructure that resemble miniature drinking straws. Such tubular microstructures are found in nature. In addition, we and others have been investigating strategies for making synthetic analogs. We are especially interested in the idea of making metal microtubules. Four procedures for preparing metal microtubules are described in this paper. The general approach, called template-synthesis, entails using the pores in a microporous membrane as templates for ... |
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| A Simple Chemical Procedure for Extending the Conductive State of Polypyrrole to More Negative Potentials |
JUN 93 |
35 pages |
| Authors:
Leon S. Van Dyke; Susumu Kuwabata; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| The electronically conductive polymer polypyrrole is an electronic conductor at potentials positive of ca. -0.4 V vs. the saturated calomel electrode (SCE) and an electronic insulator at potentials negative of this value. As a result of this potential-dependent conductor/insulator transition, a polypyrrole film can be used as an electrode for redox couples with E(o)'s positive of ca. -0.4 V vs. SCE but cannot be used as an electrode for couples ... |
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| Modification of Fluoropolymer Surfaces with Electronically Conductive Polymers |
JUN 93 |
30 pages |
| Authors:
Leon S. Van Dyke; Charles J. Brumlik; Wenbin Liang; Junting Lei; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We describes methods for coating fluoropolymer surfaces with thin films of electronically conductive polymers. Modification of the fluoropolymer surface prior to coating with conductive polymer is necessary to achieve good adhesion between the fluoropolymer membrane and the conductive polymer coating. We describe four different procedures for modifying the fluoropolymer surface so as to promote strong adhesion. These procedures are based on a wet chemical treatment of fluoropolymer or on exposure ... |
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| Electrochemical Fabrication of Cadmium Chalcogenide Microdiode Arrays |
09 APR 93 |
14 pages |
| Authors:
Jonathan D. Klein; Charles J. Brumlik; Robert Herrick; Dean Palmer; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Arrays containing greater than 10(exp 9) 2000A-diameter CdSe or graded CdSe/CdTe cylinders have been electrochemically synthesized within the pores of Anopore(tm) membranes. The alumina template suppresses the 'cauliflower' morphology that is typically observed in electrodeposited CdSe and CdTe films, although X-ray diffraction reveals the materials to be of poor crystallinity. The Anopore membrane template can be removed by treatment with aqueous 1M NaOH, resulting in an array of free-standing CdSe ... |
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| Inorganic and Biological Electron Transfer Across an Electronically Conductive Composite Polymer Membrane |
22 FEB 93 |
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| Authors:
Del R. Lawson; Wenbin Liang; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We describe in this paper an experiment involving an electronically conductive polymer that, to our knowledge, has not been described previously. A free-standing conductive polymer (polypyrrole)-based membrane separates a solution of an electron donor from a solution of an electron acceptor. Because the conductive polymer is both electronically and anionically conductive, the membrane can transport electrons from the donor solution to the acceptor solution, and anions in the opposite direction, ... |
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| Luminescence Probe Studies of Ionomers. 3. Distribution of Decay Rate Constants for Tris Bipyridyl Ruthenium(II) in Nafion Membranes |
09 FEB 93 |
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| Authors:
Jorge L. Colon; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Measurements of the luminescence lifetime of Ru(bpy) sub 3(2+) (bpy = 2,2'-bipyridine) in Nafion were used to probe the heterogeneity of -SO3H(3) sites in the Nafion membrane. The decay kinetics of the probe ion are shown to depart from simple first-order behavior. Alber's model of a continuous distribution of rate constants is used to explain the decay kinetics. The results of these and related investigations indicate that the probe ions ... |
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| Influence of the Sulfonate Countercation on the Thermal Stability of Nafion (Trade name) Perfluorosulfonate Membranes |
21 DEC 92 |
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| Authors:
Charles R. Martin; Daniel L. Feldheim; Del R. Lawson; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| We report in this paper a strong dependence of the thermal stability of Nafion perfluorosulfonate ionomer on the nature of the counterion associated with the fixed sulfonate site. These results were obtained using thermal gravimetric analysis on a series of alkali metal and alkyl ammonium cation- exchanged Nafion films. We have found that the temperature of decomposition of Nafion is inversely dependent on the size of the exchanged cation; i. ... |
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| Optical Properties of Composite Membranes Containing Arrays of Nanoscopic Gold Cylinders |
20 JUL 92 |
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| Authors:
Colby A. Foss Jr.; Gabor L. Hornyak; Jon A. Stockert; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Nano-chemistry, physics and materials are important and evolving fields in modern science. One of the most interesting aspects of nanomaterials concerns the optical properties of nanoscopic metal particles. While bulk metals are optically opaque, effective medium theory (EMT) predicts that collections of small metal particles can be transparent, provided that the wavelength of light employed is much greater than a characteristic dimension of the particle. Hence, EMT can be used ... |
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| UV Laser Ablation of Electronically Conductive Polymers |
16 JUN 92 |
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| Authors:
Leon S. Van Dyke; Charles J. Brumlik; Zengi Yu; George J. Collins; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| The UV laser ablation of thin polypyrrole and polyaniline films coated on an insulating substrate is described. UV laser ablation is used to pattern the conductive polymer coating; patterns with submillimeter features are easily obtained with edge resolution on the order of a few microns. Electronically conductive polymers, laser ablation, microlithography. |
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| Effect of Synthesis Temperature in the Structure, Doping Level and Charge-Transport Properties of Polypyrrole |
08 MAY 92 |
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| Authors:
Wenbin Liang; Junting Lei; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| Polypyrrole perchlorate was chemically synthesized at various temperatures and the resulting polymers were investigated by elemental analysis, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and conductivity measurements. A correlation between conductivity, doping level and synthesis temperature was observed. The doping level of the polymer is higher when the synthesis is conducted at lower temperature exhibit longer conjugation length, fewer structural defects, higher charge carrier hopping frequency and higher ... |
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| Infrared Investigations of Pristine, Doped and Partially-Doped Polypyrrole |
08 MAY 92 |
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| Authors:
J. Lei; W. Liang; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
|
| It is well known that pristine (i.e. undoped) polypyrrole is not air- stable. As a result, it is difficult to obtain spectral data for the pristine polymer. Indeed, there are only two reports of infrared (IR) absorption spectra for the pristine material in the literature and, in both cases, the polymer seems to have undergone some air oxidation. It would be highly desirable to have reliable and reproducible IR spectra ... |
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| Infrared Investigations of Pristine Polypyrrole - Is the Polymer Called Polypyrrole Really Poly(Pyrrole-Co-Hydroxypyrrole)? |
30 APR 92 |
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| Authors:
Junting Lei; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| Polypyrrole (PPY) is one of the most extensively investigated of the electronically conductive polymers. Nevertheless, there is still much we don't understand about this interesting and useful material. One of the most persistent mysteries involves simple chemical composition. Doped PPy should have the empirical formula C4 H3 NX where X is the dopant counterion and z is the fractional doping level; z is typically on the order of 0.3. However, ... |
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| Polyphosphazenes Bearing Polymerizable Pyrrole, thiophene and Furan Side Groups: Synthesis and Chemical Oxidation |
30 APR 92 |
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| Authors:
Harry R. Allcock; Jeffrey A. Dodge; Leon S. Van Dyke; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| The synthesis and chemical oxidation of linear poly(organophosphazenes) that bear polymerizable, heterocyclic side groups is described. The polymers were prepared for use as precursors to electronically conductive materials. (See reverse side of this paper) conductive polymers, synthetic metals, electronic conductivity. |
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| Template-Synthesis: A Method for Enhancing the Ionic and Electronic Conductivity in Electronically Conductive Polymers |
16 APR 92 |
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| Authors:
Charles R. Martin; Leon S. Van Dyke; Zhihua Cai; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| Template-synthesis entails the synthesis of an electronically conductive polymer (or other material) within the pores of a microporous membrane. The membranes used have cylindrica pores of equivalent pore diameter; as a result, polymeric fibers are obtained, where the diameters of the fibers are determined by the diameter of the pores in the template membrane. We show in this paper that template-synthesized polypyrrole fibers show faster rates of charge transport, during ... |
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| Electrochemical Investigations of Electronically Conductive Polymers. VII. Charge-Transport in Lightly-Doped Polypyrrole |
13 SEP 91 |
39 pages |
| Authors:
Zhihau Cai; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| We have shown that the mechanism and rate of charge transport in polypyrrole films (on electrode surface) depend on whether the polymer is in its electronically conductive or electronically insulating state. This paper focuses on the mechanism and rate of charge transport in the electronically insulating state; i.e. we describe results of electrochemical investigations of polypyrrole films which were equilibrated at initial potentials negative of -0.30 V vs. SCE. With ... |
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| Molecular and Supermolecular Origins of Enhanced Electronic Conductivity in Template-Synthesized Polyheterocyclic Fibrils. Part 1. Supermolecular Effects |
18 JUL 91 |
51 pages |
| Authors:
Zhihua Cai; Junting Lei; Wenbin Liang; Charles R. Martin; COLORADO STATE UNIV FORT COLLINS DEPT OF CHEMISTRY
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| The pores in a nanoporous membrane can be used as templates for the synthesis of nanostructures. We have recently shown that conductive polymer fibrils, obtained via this template synthetic method, can show dramatically higher electronic conductivities than conventional versions of the analogous polymers. In this and a succeeding paper we explore the molecular and supermolecular origins of this enhanced electronic conductivity. This paper focuses on supermolecular effects. We have used ... |
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