Nanomaterials: a membrane-based synthetic approach.
23 Dec 1994-Science (American Association for the Advancement of Science)-Vol. 266, Iss: 5193, pp 1961-1966
TL;DR: A relatively new method for preparing nanomaterials, membrane-based synthesis, is reviewed, which entails synthesis of the desired material within the pores of a nanoporous membrane.
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.
Citations
More filters
TL;DR: In this article, surface-enhanced Raman scattering was used to detect single molecules and single nanoparticles at room temperature with the use of surface enhanced Raman, and 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.
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.
9,609 citations
7,711 citations
TL;DR: Studies carried out with different conditions and catalyst materials confirmed the central details of the growth mechanism and suggest that well-established phase diagrams can be used to predict rationally catalyst materials and growth conditions for the preparation of nanowires.
Abstract: A method combining laser ablation cluster formation and vapor-liquid-solid (VLS) growth was developed for the synthesis of semiconductor nanowires. In this process, laser ablation was used to prepare nanometer-diameter catalyst clusters that define the size of wires produced by VLS growth. This approach was used to prepare bulk quantities of uniform single-crystal silicon and germanium nanowires with diameters of 6 to 20 and 3 to 9 nanometers, respectively, and lengths ranging from 1 to 30 micrometers. Studies carried out with different conditions and catalyst materials confirmed the central details of the growth mechanism and suggest that well-established phase diagrams can be used to predict rationally catalyst materials and growth conditions for the preparation of nanowires.
4,405 citations
TL;DR: In this article, the authors discuss the development of a general approach to rational synthesis of crystalline nanowires of arbitrary composition, and illustrate solutions to these challenges with measurements of the atomic structure and electronic properties of carbon nanotubes.
Abstract: Dimensionality plays a critical role in determining the properties of materials due to, for example, the different ways that electrons interact in three-dimensional, twodimensional (2D), and one-dimensional (1D) structures.1-5 The study of dimensionality has a long history in chemistry and physics, although this has been primarily with the prefix “quasi” added to the description of materials; that is, quasi-1D solids, including square-planar platinum chain and metal trichalcogenide compounds,2,6 and quasi2D layered solids, such as metal dichalcogenides and copper oxide superconductors.3-5,7,8 The anisotropy inherent in quasi-1D and -2D systems is central to the unique properties and phases that these materials exhibit, although the small but finite interactions between 1D chains or 2D layers in bulk materials have made it difficult to address the interesting properties expected for the pure low-dimensional systems. Are pure low-dimensional systems interesting and worth pursuing? We believe that the answer to this question is an unqualified yes from the standpoints of both fundamental science and technology. One needs to look no further than past studies of the 2D electron gas in semiconductor heterostructures, which have produced remarkably rich and often unexpected results,9,10 and electron tunneling through 0D quantum dots, which have led to the concepts of the artificial atom and the creation of single electron transistors.11-15 In these cases, lowdimensional systems were realized by creating discrete 2D and 0D nanostructures. 1D nanostructures, such as nanowires and nanotubes, are expected to be at least as interesting and important as 2D and 0D systems.16,17 1D systems are the smallest dimension structures that can be used for efficient transport of electrons and optical excitations, and are thus expected to be critical to the function and integration of nanoscale devices. However, little is known about the nature of, for example, localization that could preclude transport through 1D systems. In addition, 1D systems should exhibit density of states singularities, can have energetically discrete molecularlike states extending over large linear distances, and may show more exotic phenomena, such as the spin-charge separation predicted for a Luttinger liquid.1,2 There are also many applications where 1D nanostructures could be exploited, including nanoelectronics, superstrong and tough composites, functional nanostructured materials, and novel probe microscopy tips.16-29 To address these fascinating fundamental scientific issues and potential applications requires answers to two questions at the heart of condensed matter chemistry and physics research: (1) How can atoms or other building blocks be rationally assembled into structures with nanometer-sized diameters but much longer lengths? (2) What are the intrinsic properties of these quantum wires and how do these properties depend, for example, on diameter and structure? Below we describe investigations from our laboratory directed toward these two general questions. The organization of this Account is as follows. In section II, we discuss the development of a general approach to the rational synthesis of crystalline nanowires of arbitrary composition. In section III, we outline key challenges to probing the intrinsic properties of 1D systems and illustrate solutions to these challenges with measurements of the atomic structure and electronic properties of carbon nanotubes. Last, we discuss future directions and challenges in section IV.
3,218 citations
TL;DR: This review attempts to cover all aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.
Abstract: TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.
2,735 citations
References
More filters
TL;DR: In this paper, the synthesis, characterization, and proposed mechanism of formation of a new family of silicatelaluminosilicate mesoporous molecular sieves designated as M41S is described.
Abstract: The synthesis, characterization, and proposed mechanism of formation of a new family of silicatelaluminosilicate mesoporous molecular sieves designated as M41S is described. MCM-41, one member of this family, exhibits a hexagonal arrangement of uniform mesopores whose dimensions may be engineered in the range of - 15 A to greater than 100 A. Other members of this family, including a material exhibiting cubic symmetry, have ken synthesized. The larger pore M41S materials typically have surface areas above 700 m2/g and hydrocarbon sorption capacities of 0.7 cc/g and greater. A templating mechanism (liquid crystal templating-LCT) in which surfactant liquid crystal structures serve as organic templates is proposed for the formation of these materials. In support of this templating mechanism, it was demonstrated that the structure and pore dimensions of MCM-41 materials are intimately linked to the properties of the surfactant, including surfactant chain length and solution chemistry. The presence of variable pore size MCM-41, cubic material, and other phases indicates that M41S is an extensive family of materials.
10,349 citations
Book•
01 Jan 1986
TL;DR: In this paper, the authors presented the theory and properties of conjugated polymers, including transport, optical, and self-assembly properties of poly(3,4-Ethylenedioxythiophene)-polymers.
Abstract: Volume 1: Conjugated Polymers: Theory, Synthesis, Properties, and Characterization PART 1: THEORY OF CONJUGATED POLYMERS On the Transport, Optical, and Self-Assembly Properties of -Conjugated Materials: A Combined Theoretical/Experimental Insight D. Beljonne, J. Cornil, V. Coropceanu, D.A. da Silva Filho, V. Geskin, R. Lazzaroni, P. Leclere, and J.-L. Bredas Theoretical Studies of Electron-Lattice Dynamics in Organic Systems S. Stafstroem PART 2: SYNTHESIS AND CLASSES OF CONJUGATED POLYMERS Helical Polyacetylene Synthesized in Chiral Nematic Liquid Crystals K. Akagi Synthesis and Properties of Poly(arylene vinylene)s A.C. Grimsdale and A.B. Holmes Blue-Emitting Poly(para-Phenylene)-Type Polymers E.J.W. List and U. Scherf Poly(paraPhenyleneethynylene)s and Poly(aryleneethynylene)s: Materials with a Bright Future U.H.F. Bunz Polyaniline Nanofibers: Synthesis, Properties, and Applications J. Huang and R.B. Kaner Recent Advances in Polypyrrole S.H. Cho, K.T. Song, and J.Y. Lee Regioregular Polythiophenes M. Jeffries-El and R.D. McCullough Poly(3,4-Ethylenedioxythiophene)-Scientific Importance, Remarkable Properties, and Applications S. Kirchmeyer, K. Reuter, and J.C. Simpson Thienothiophenes: From Monomers to Polymers G.A. Sotzing, V. Seshadri, and F.J. Waller Low Bandgap Conducting Polymers S.C. Rasmussen and M. Pomerantz Advanced Functional Polythiophenes Based on Tailored Precursors P. Blanchard, P. Leriche, P. Frere, and J. Roncali Structure-Property Relationships and Applications of Conjugated Polyelectrolytes K.S. Schanze and X. Zhao PART 3: PROPERTIES AND CHARACTERIZATION OF CONJUGATED POLYMERS Insulator-Metal Transition and Metallic State in Conducting Polymers A.J. Epstein One-Dimensional Charge Transport in Conducting Polymer Nanofibers A.N. Aleshin and Y.W. Park Structure Studies of - and - Conjugated Polymers M.J. Winokur Electrochemistry of Conducting Polymers P. Audebert and F. Miomandre Internal Fields and Electrode Interfaces in Organic Semiconductor Devices: Noninvasive Investigations via Electroabsorption T.M. Brown and F. Cacialli Electrochromism of Conjugated Conducting Polymers A.L. Dyer and J.R. Reynolds Photoelectron Spectroscopy of Conjugated Polymers M.P. de Jong, G. Greczyniski, W. Osikowicz, R. Friedlein, X. Crispin, M. Fahlman, and W.R. Salaneck Ultrafast Exciton Dynamics and Laser Action in -ConjugatedSemiconductors Z. Valy Vardeny and O. Korovyanko Volume 2: Conjugated Polymers: Processing and Applications PART 1: PROCESSING OF CONJUGATED POLYMERS Conductive Polymers as Organic Nanometals B. Wessling Conducting Polymer Fiber Production and Applications I.D. Norris and B.R. Mattes Inkjet Printing and Patterning of PEDOT-PSS: Application to Optoelectronic Devices Y. Yoshioka and G.E. Jabbour Printing Organic Electronics on Flexible Substrates N.D. Robinson and M. Berggren PART 2: APPLICATIONS AND DEVICES BASED ON CONJUGATED POLYMERS Polymers for Use in Polymeric Light-Emitting Diodes: Structure-Property Relationships H. Christian-Pandya, S. Vaidyanathan, and M. Galvin Organic Electro-Optic Materials L.R. Dalton Conjugated Polymer Electronics-Engineering Materials and Devices N. Tessler, J. Veres, O. Globerman, N. Rappaport, Y. Preezant, Y. Roichman, O. Solomesch, S. Tal, E. Gershman, M. Adler, V. Zolotarev, V. Gorelik, and Y. Eichen Electrical Bistable Polymer Films and Their Applications in Memory Devices J. Ouyang, C.-W. Chu, R.J. Tseng, A. Prakash, and Y. Yang Electroactive Polymers for Batteries and Supercapacitors J.A. Irvin, D.J. Irvin, and J.D. Stenger-Smith Conjugated Polymer-Based Photovoltaic Devices A.J. Mozer and N.S. Sariciftci Biomedical Applications of Inherently Conducting Polymers (ICPs),P.C. Innis, S.E. Moulton, and G.G. Wallace Biosensors Based on Conducting Electroactive Polymers S. Brahim, A.M. Wilson, and A. Guiseppi-Elie Optical Biosensors Based on Conjugated Polymers K. Peter, R. Nilsson, and O. Inganas Conjugated Polymers for Microelectromechanical and Other Microdevices G.M. Spinks and E. Smela Corrosion Protection Using Conducting Polymers D.E. Tallman and G.P. Bierwagen Artificial Muscles T.F. Otero
5,843 citations
TL;DR: Monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks and exhibited dramatically increased blood circulation times and reduced liver accumulation in mice.
Abstract: Injectable nanoparticulate carriers have important potential applications such as site-specific drug delivery or medical imaging. Conventional carriers, however, cannot generally be used because they are eliminated by the reticulo-endothelial system within seconds or minutes after intravenous injection. To address these limitations, monodisperse biodegradable nanospheres were developed from amphiphilic copolymers composed of two biocompatible blocks. The nanospheres exhibited dramatically increased blood circulation times and reduced liver accumulation in mice. Furthermore, they entrapped up to 45 percent by weight of the drug in the dense core in a one-step procedure and could be freeze-dried and easily redispersed without additives in aqueous solutions.
2,827 citations
IBM1
1,531 citations