Charles R. Martin

Bio: Charles R. Martin is an academic researcher from University of Florida. The author has contributed to research in topics: Membrane & Conductive polymer. The author has an hindex of 102, co-authored 358 publications receiving 41696 citations. Previous affiliations of Charles R. Martin include University of Maryland, College Park & Colorado State University.

Nanomaterials: a membrane-based synthetic approach.

Abstract: Materials with nanoscopic dimensions not only have potential technological applications in areas such as device technology and drug delivery but also are of fundamental interest in that the properties of a material can change in this regime of transition between the bulk and molecular scales. In this article, a relatively new method for preparing nanomaterials, membrane-based synthesis, is reviewed. This method entails synthesis of the desired material within the pores of a nanoporous membrane. Because the membranes used contain cylindrical pores of uniform diameter, monodisperse nanocylinders of the desired material, whose dimensions can be carefully controlled, are obtained. This "template" method has been used to prepare polymers, metals, semiconductors, and other materials on a nanoscopic scale.

Carbon nanotubule membranes for electrochemical energy storage and production

Abstract: Ensembles of aligned and monodisperse tubules of graphitic carbon can be prepared by a templating method1,2,3,4 that involves the chemical-vapour deposition of carbon within the pores of alumina membranes5,6,7. Tubules with diameters as small as 20 nm have been prepared in this way7,8. The carbon comprising these tubules can be transformed from a disordered material to very highly ordered graphite5. Here we show that template-synthesized carbon tubules can be fabricated as free-standing nanoporous carbon membranes, and that narrower, highly ordered graphitic carbon nanotubes can be prepared within the membrane's tubules. Both the outer and the inner tubules are electrochemically active for intercalation of lithium ions, suggesting possible applications in lithium-ion batteries9,10. The membranes can also be filled with nanoparticles of electrocatalytic metals and alloys. Such catalyst-loaded membranes can be used to electrocatalyse O2 reduction and methanol oxidation, two reactions of importance to fuel-cell technology.

Membrane-Based Synthesis of Nanomaterials

Abstract: This paper 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 approach the “template” method because the pores in the nanoporous membranes are used as templates for forming the desired material. This template method is a very general approach; it has been used to prepare nanotubules and fibrils of polymers, metals, semiconductors, carbons, and other materials.

A general template-based method for the preparation of nanomaterials

Abstract: This article reviews a general template-based approach for the preparation of nanomaterials. The method involves the synthesis of a desired material within the pores of a nanoporous membrane. We have termed this approach ‘template synthesis’ because the pores within these nanoporous membranes act as templates for the synthesis of nanostructures of the desired material. Because the pores within these membranes are cylindrical and of uniform diameter, monodisperse nanocylinders of the desired material are obtained. Depending on the chemistry of the pore wall and material, these nanocylinders may be either hollow (a tubule) or solid (a fibril or nanowire). This template process will be shown to be a very general approach in the fabrication of nanotubes and fibrils composed of a variety of materials including polymers, metals, semiconductors, carbons, and other materials.

Template Synthesis of Electronically Conductive Polymer Nanostructures

Abstract: : 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 of uniform diameter. In essence, we view each of these pores as a "nanobeaker" in which a piece of the desired material is synthesized. We have used this method to prepare nanostructures composed of electronically conductive polymers, metals, semiconductors, and other materials. In this Accounts article, I discuss my work on template synthesis of electronically conductive polymer nanostructures. I will show that these conductive polymer nanostructures have interesting and unusual electronic properties and that these nanostructures provide an opportunity for exploring how molecular and supermolecular structure affect conductivity in conductive polymers.

Probing Single Molecules and Single Nanoparticles by Surface-Enhanced Raman Scattering

Abstract: Optical detection and spectroscopy of single molecules and single nanoparticles have been achieved at room temperature with the use of surface-enhanced Raman scattering. Individual silver colloidal nanoparticles were screened from a large heterogeneous population for special size-dependent properties and were then used to amplify the spectroscopic signatures of adsorbed molecules. For single rhodamine 6G molecules adsorbed on the selected nanoparticles, the intrinsic Raman enhancement factors were on the order of 10 14 to 10 15 , much larger than the ensemble-averaged values derived from conventional measurements. This enormous enhancement leads to vibrational Raman signals that are more intense and more stable than single-molecule fluorescence.

The Optical Properties of Metal Nanoparticles: The Influence of Size, Shape, and Dielectric Environment

Abstract: The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangula...

Nanostructured materials for advanced energy conversion and storage devices

Abstract: New materials hold the key to fundamental advances in energy conversion and storage, both of which are vital in order to meet the challenge of global warming and the finite nature of fossil fuels. Nanomaterials in particular offer unique properties or combinations of properties as electrodes and electrolytes in a range of energy devices. This review describes some recent developments in the discovery of nanoelectrolytes and nanoelectrodes for lithium batteries, fuel cells and supercapacitors. The advantages and disadvantages of the nanoscale in materials design for such devices are highlighted.

A review on polymer nanofibers by electrospinning and their applications in nanocomposites

Abstract: Electrospinning has been recognized as an efficient technique for the fabrication of polymer nanofibers. Various polymers have been successfully electrospun into ultrafine fibers in recent years mostly in solvent solution and some in melt form. Potential applications based on such fibers specifically their use as reinforcement in nanocomposite development have been realized. In this paper, a comprehensive review is presented on the researches and developments related to electrospun polymer nanofibers including processing, structure and property characterization, applications, and modeling and simulations. Information of those polymers together with their processing conditions for electrospinning of ultrafine fibers has been summarized in the paper. Other issues regarding the technology limitations, research challenges, and future trends are also discussed.