Nanostructured Conductive Polymers E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Sprache: Englisch

Seitenzahl: 1612

Veröffentlichungsjahr: 2011

Beschreibung

Providing a vital link between nanotechnology and conductive polymers, this book covers advances in topics of this interdisciplinary area. In each chapter, there is a discussion of current research issues while reviewing the background of the topic. The selection of topics and contributors from around the globe make this text an outstanding resource for researchers involved in the field of nanomaterials or polymer materials design. The book is divided into three sections: From Conductive Polymers to Nanotechnology, Synthesis and Characterization, and Applications.

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Library of Congress Cataloging-in-Publication Data

Nanostructured conductive polymers/ edited by Ali Eftekhari. p. cm.Includes bibliographical references and index. ISBN 978-0-470-74585-4 (cloth)1. Nanostructured materials. 2. Conducting polymers. I. Eftekhari, Ali, 1979-TA418.9N35N3522 2010 620.1′92—dc222010005168

Preface

In October 2000 when the winners of Nobel Prize in Chemistry were announced, I sent a greeting card to Alan J. Heeger for congratulating him on this honor and his pioneering works on conductive polymers. Professor Heeger replied me by the following note “This Prize was awarded to the field of semconducting and metallic polymers. You, as one with direct research experience in this field, have a right to be proud.” A few months later I was in a position to defend a research proposal, and in reply to the question of one of the panelists “Is it a well-established subject with practical potentials or just fancy subject for academic projects”, I had a convincing answer, and felt the glory of that award.

Nanotechnology and conductive polymers approximately have the same age, but contrary to the field of conductive polymers, which was abruptly introduced in a Short Communication, nanotechnology was emerged gradually through journey from micro-technology to smaller scales. There are two distinguishable aspects about nanotechnology, but this distinction is usually ignored: advancing our technology by taking control at smaller scales (an advanced form of microtechnology), or entering a new world at nanoscale because its scale is comparable with the molecular size. The fame of nanotech-nology belongs to the latter one, but most of research studies are restricted to the first aspect.

Due to the interdisciplinary nature of nanotechnology, researchers from various disciplines have been involved in the rapid growth of nanotechnology as a promising field of study. One of the most active areas is polymer nanotechnology owing to the size of polymer chains. Advancement of nanotechnology tools has provided a rare opportunity to investigate individual chains of polymers. On the other hand, polymers as a member of soft matter family have incredible flexibility for the preparation of various nanostructures, particularly for nano-devices.

The emerging field of conductive polymers itself is indeed an interdisciplinary field, as the essential conductivity has well connected this field to other disciplines (which were not usually associated with polymer materials) from electrochemistry to electrical engineering. Now the emerging field at the interface of nanotechnology and conductive polymers covers a vast variety of quite different disciplines; which calls for more collaboration between researchers with different professions and knowledge. The present book and similar volumes aim to introduce new opportunities by linking different topics involved in this emerging field.

The present book does not claim to provide an ultimately comprehensive resource on the field, and it is almost impossible; but as far as possible, I tried to collect most active areas of research. More than 80 referees assisted me to assure the scientific quality of this book. Although all chapters were solicited in advance, some of contributions were rejected as they did not meet the required standard, and there was insufficient time to call for a replacement by another author. In addition, some authors agreed to deliver their manuscripts by the given deadline but simply declined to submit their contributions in due time. Thus, the audience may feel that some topics have been missed.

As a matter of fact, we are still far from ultimate control at nanoscale as claimed by the mission of nanotechnology; thus, the subjects discussed here are mainly at the interface of transition from micro- to nano-world. This is indeed a transition from the first to second decade of third millennium. This book builds a bridge to the forthcoming decade in which we expect to witness incredible advancement in the realms of nanotechnology. The present book aims to lead researchers from different disciplines in this direction and somehow unite them to think about emerging problems from quite different perspectives.

The book starts with an introductory chapter about conductive polymers. For those who are familiar with nanotechnology, this chapter is a guiding star; and for polymer scientists, it is a reminder that from where we have started. The two next chapters are typical ones to introduce the realms of nanostructured conductive polymers. Polyaniline is considered as a prototype and among most popular conductive polymers. Chapter 3 discusses some interesting features in surface studies of conductive polymer, while surface analysis is always a key concept in the realm of nanotechnology.

The second part of the book commences with a series of papers devoted to a variety of nanomaterials made of conductive polymers, and later introduces some important properties of conductive polymers and methodology of the field. Electrospining is an effective method for the preparation of a variety of nanomaterials, and it has been widely utilized for the fabrication of conductive polymers. Carbon nanotubes are indeed the most dominant prototype of nanomaterials, as they are among the first prototypes of nanomaterial which were introduced to the market in abundance; thus, nanocomposites based on carbon nanotubes have attracted a considerable attention, particularly due to the special conductivity of carbon nanotubes and conductive polymers. Due to the intrinsic difference between inorganic and polymer materials (soft matter vs. rigid structure), this type of composites has long attracted a noticeable attention. Now structural entanglement at nanoscale has provided rare opportunities for the formation of interesting nano-composites. This is of particular interest when dealing with inorganic materials and conductive polymers which both have ionic properties and conductivity, and the resulting nanocomposites have a wide variety of applications. Metallic nanoparticles are usually too small, leading to severe difficulties in handling the nanomaterials, and soft structure of polymers is an appropriate medium to host such tiny nanoparticles. Again electrical conductivities of both ingredients of this class of nanocomposites lead to potential applications.

Like all types of polymers, conductive polymers are first characterised by spectroscopic techniques, and this is of particular importance for nanostructured materials too. Atomic force microscopy (AFM) is a powerful (and relatively inexpensive) microscopic technique for surface studies at nanoscale, and sometimes this is essential for the investigation of conductive polymers. Despite available limitations, progress in nanodevices has provided new opportunities for the study of single molecules. Study of single wires of polymers is quite easy due to the size of the polymer chains. An interesting feature recently reported is the possibility of preparation of micro- and nano-containers of conductive polymers which can have potential applications. Magnetic properties and electron transfer in nanocomposites made of conductive polymers are complicated which need profound investigations. An important application of conductive polymers is in solar cells, but to reach effective performances, it is necessary to inspect charge transfer theoretically.

The last part of the book reviews some important applications of conductive polymers which have been evolved by the birth of nanotechnology. Chemical and electrochemical sensors based on conductive polymers have been effectively fabricated during the past decades, and now nanomaterials have significantly improved the sensor performances. In recent years a noticeable attention has been paid to polymer-based actuators, and according to potential applications at smaller scales, nanostructured-based polymers play key roles in this case. From the first electrochemical synthesis of conductive polymers, they have been propounded for the protection of metal surfaces against corrosion as a thin layer could be simply electrodeposited. Possibility for the coating of uniform with small thickness has made this idea more practical. Electrochemically prepared conductive polymers show excellent electrocatalytic properties (and particularly in electroactive composites) and due to the enhanced electrochemical properties of nanostructured materials, this is an open issue in the realms of nanotechnology. Polymers are generally a dominant category in biomaterials, and due to the fictional prospective of nanotechnology to make a revolution in medicine, it is always interesting to inspect biomedical applications of polymer nanomaterials. Taking control at nanoscale provides golden opportunities; for instance, conductive polymers are not limited to polymers which are originally conductive, but it is possible to make conductive polymer-based nanocomposites by nanofillers.

The subjects quoted above are among hot topics in the interfacial field between conductive polymers and nanotechnology, which have been elaborately discussed by leading scientists. Each chapter reviews the past by citing key references through a comprehensive review of the literature, discusses the present by reporting recent and forthcoming achievements, and draws the future by introducing a prospective of the topic under consideration. As emphasised before, the present book should play a role in transition from the present to future as we are just in the beginning of a new stage in the realms of nanotechnology. Until now we were engaged with the birth of nanotechnology, but now it is the time for maturing this rapidly growing field. We witnessed many incredible but random achievements in different disciplines associated with nanotechnol-ogy; however, now we need to conduct the scientific research in desirable ways to reach planned goals.

At last but not least, I need to thank those people whose names are not printed in this book, but the publication of this volume would not have been possible without their hard efforts. The list of people from scientific referees to technical staff is too long to be incorporated here; but I must send my special thanks to Alexandra Carrick, Emma Strickland, and Richard Davies. I could not forget how they have worked with me with patience on a daily basis. One may think it is just formalities and as a part of publication industry everyone does her/his duty; but the fact is that in such a complicated process, sincere collaborations and mutual understanding between all parties involved can lead to the publication of a brilliant volume. Definitely, it was the case for the present book, and I hope we are successful in contributing to the scientific community. Although it was a team work, any failure returns to me as the coordinator of this book project; thus, I strongly appreciate any comment, which will be invaluable for me in editing prospective volumes.

Ali Eftekhari

January 2010

Foreword

In the recent decades, the field of conductive polymers has been one of the most exciting fields of science and technology. It has brought together scientists from many disciplines and countries. This great progress has involved synthesis of materials closely linked to physical characterisation. With the development of this field, a wide range of applications have been envisaged, presenting their own research challenges and stimulating further innovation. It discovery, provided new materials and frequently also reflected back on our understanding at a more fundamental level. Throughout, the interplay of structure and properties has been at the heart of the subject, and now this book reviews the field with particular emphasis on nanostructure. It elegantly captures the key features of the field outlined above: the quest to make materials, relate their properties to their structure, the favourable interplay of basic and applied research, and the realisation of materials that could only have been dreamt of in the past.

The opening chapter by Campbell Scott gives an eloquent, insightful and personal history of the subject by a leading researcher whose career has spanned, what he describes as, the modern age of materials. The subsequent chapters show an enormous range of ways of synthesising and preparing nanostructured conductive polymers in many different forms – nanofibres, nanorods, nanotubes, nanospheres and even “brainlike” morphologies. Besides covering chemical and electrochemical synthesis methods, the chapters are devoted to advanced processing techniques for nanostructure fabrication, such as electrospinning and soft lithography. Conductive polymers can be blended with a range of other materials such as nanoparticles and carbon nanotubes, leading to nanocomposite materials with additional properties. Many interesting examples discussed in this volume range from magnetic composite materials to conductive nanogreases.

The development of nanostructured conductive polymers also requires the development of advanced characterisation techniques, and this aspect of current research is captured in several chapters. A detailed review of Atomic Force Microscopy (AFM) covers the wide range of related scanning probe microscopes that are particularly relevant to soft materials. It also shows how techniques such as conductive AFM go beyond structural measurements to image the functional properties of materials relevant to applications such as solar cells. A wide range of spectroscopic techniques has also been reviewed, showing how they can be applied to learn about the interactions between conductive polymers and nanostructured hosts. In addition, rheological measurements as well as the impact of nanostructure on electrical and optical properties have been described.

This book covers the remarkable range of applications emerging for nanostructured conductive polymers. These applications generally exploit the increased surface area of nanostructured materials, often to do something very new. One very important example is of polymer solar cells, where nanoscale phase separation lies at the heart of charge generation and extraction. Another exciting application domain is the use of nanostruc-tured conductive polymers as biomaterials, including the development of neural interfaces. Other applications described include sensors, actuators, corrosion protection and electrocatalysis.

Each chapter provides a comprehensive review by a leading researcher. But a bigger picture emerges from reading all the chapters together – it reveals how we are now working with new classes of materials, new techniques and how the quest to link properties to structure is advancing at the nanoscale. The ensemble of all the chapters captures the excitement and potential of this field, whilst beautifully demonstrating the interdisciplinary and international nature of modern science.

Ifor Samuel, St Andrews,

May 2010

List of Contributors

Agnese Abrusci, Optoelectronics Group, Cavendish Laboratory, Cambridge, U.K.

Alain Pailleret, CNRS UPR, Laboratoire d’Electrochimie et de Chimie Analytique, Ecole Nationale Supérieure de Chimie de Paris, Paris, France.

Anthony J. Killard, Sensors and Separations Group, School of Chemical Sciences, Dublin City University, Dublin, Ireland.

David Cocke, Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas, USA.

Di Zhang, Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas, USA.

Dustin Thomas, Department of Material and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA .

Edgar Ap. Sanches, Institute of Physics of São Carlos (IFSC), University of São Paulo, São Carlos, SP, Brazil.

Fabio de Lima Leite, Federal University of São Carlos (UFSCar), Sorocaba, SP, Brasil.

Gordana Ćirić-Marjanović, Faculty of Physical Chemistry, University of Belgrade, Belgrade, Serbia.

Gustavo M. do Nascimento, Departamento de Química Fundamental, Universidade de São Paulo, São Paulo, Brazil.

Haiping Hong, Department of Material and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA.

Hyacinthe Randriamahazaka, Laboratoire Interfaces Traitements et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS –Université Denis Diderot Paris, Paris, France.

I. Baltog, National Institute of Materials Physics, Bucharest, Romania.

Ian A. Howard, Max Planck Institute for Polymer Research, Mainz, Germany.

Ioannis S. Chronakis, Swerea IVF, Swedish Institute for Industrial Research and Development, Mölndal, Sweden.

J. Campbell Scott, IBM Almaden Research Center, San Jose CA.

Jadranka Travas-Sejdic, Polymer Electronics Research Centre, The University of Auckland, Auckland, New Zealand.

Jalal Ghilane, Laboratoire Interfaces Traitements et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS –Université Denis Diderot Paris, Paris, France.

Jean-Christophe Lacroix, Laboratoire Interfaces Traitements et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS –Université Denis Diderot Paris, Paris, France.

Jing Li, Nanotechnology Branch, NASA Ames Research Center, CA, USA.

Jiyong Huang, National Center for Nanoscience and Technology, Beijing, P. R. China.

Laura A. Poole-Warren, Graduate School of Biomedical Engineering, University of New South Wales, Sydney NSW, AUSTRALIA.

M. Baibarac, National Institute of Materials Physics, Bucharest, Romania.

Marcelo A. de Souza, Departamento de Química Fundamental, Universidade de São Paulo, São Paulo, Brazil.

Mark Horton, Department of Material and Metallurgical Engineering, South Dakota School of Mines and Technology, Rapid City, SD, USA.

Neil C. Greenham, Optoelectronics Group, Cavendish Laboratory, Cambridge, U.K.

Nigel H. Lovell, Graduate School of Biomedical Engineering, University of New South Wales, Sydney NSW, AUSTRALIA.

Oleg Semenikhin, Department of Chemistry, University of Western Ontario, London, Ontario, Canada.

Osvaldo N. Oliveira Jr., Institute of Physics of São Carlos (IFSC), University of São Paulo, São Carlos, SP, Brazil.

Paul A. Kilmartin, Polymer Electronics Research Centre, The University of Auckland, Auckland, New Zealand.

Pauline Smith, Army Research Lab, Aberdeen Proving Ground, MD, USA.

Pierre Camille Lacaze, Laboratoire Interfaces Traitements et Dynamique des Systèmes (ITODYS), UMR 7086, CNRS –Université Denis Diderot Paris, Paris, France.

Rabin Bissessur, Department of Chemistry, University of Prince Edward Island, Charlottetown, Canada.

Richard H. Friend, Optoelectronics Group, Cavendish Laboratory, Cambridge, U.K.

Rylie A. Green, Graduate School of Biomedical Engineering, University of New South Wales, Sydney NSW, AUSTRALIA.

S. Lefrant, Institut des Matériaux Jean Rouxel, Nantes, France.

Sebastian Westenhoff, Department of Chemistry, Biochemistry & Biophysics, University of Gothenburg, Gothenburg, Sweden.

Shaolin Mu, Department of Chemistry, Yangzhou University, Yangzhou, China.

Sungchul Baek, Graduate School of Biomedical Engineering, University of New South Wales, Sydney NSW, AUSTRALIA.

Suying Wei, Department of Chemistry and Physics, Lamar University, Beaumont, TX, USA.

Vessela Tsakova, Institute of Physical Chemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria.

Walter Roy, Army Research Lab, Aberdeen Proving Ground, MD, USA.

Ya Zhang, School of the Environment, Nanjing University, Nanjing, China.

Yi Luo, Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.

Yijiang Lu, Nanotechnology Branch, NASA Ames Research Center, CA, USA.

Yixuan Chen, Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA.

Zhanhu Guo, Integrated Composites Laboratory (ICL), Dan F. Smith Department of Chemical Engineering, Lamar University, Beaumont, Texas, USA.

Zhixiang Wei, National Center for Nanoscience and Technology, Beijing, P. R. China.

Part One

1

History of Conductive Polymers

J. Campbell Scott

IBM Almaden Research Center, San Jose CA

1.1 Introduction

It is generally recognized that the modern study of electric conduction in conjugated polymers began in 1977 with the publication by the group at the University of Pennsylvania [1] describing the doping of polyacetylene. Although there was some prior work dating back to World War II (see the review by Hush [2]) and even reports of electrochemical synthesis the nineteenth century [3], the Nobel Committee recognized the seminal contribution of Heeger [4], MacDiarmid [5] and Shirakawa [6] by awarding them the Nobel Prize for Chemistry in 2000. Shirakawa, who was based at the Tokyo Institute of Technology, had been visiting the lab of his collaborators at Pennsylvania at the time of the breakthrough research.

The story of polyacetylene is an example of a fortunate confluence of circumstances that is often under-appreciated in the history of scientific progress. In the 1970s, there was worldwide interest in the unique properties of materials with such a high degree of anisotropy that they can be considered one-dimensional (1D) systems. The Pennsylvania group, of which I was privileged to be a member until 1975, was jointly led by a chemist, Tony Garito, and a physicist, Alan Heeger, and was recognized worldwide as a primary center for that field. Early focus was on the study of charge-transfer salts, in which planar, conjugated, small molecules were stacked like poker chips. Experiments revealed a Peierls transition [7,8] and suggested the observation of Fro¨lich superconductivity [9,10]. The emphasis then shifted to linear polymers as chemist, Alan MacDiarmid, entered into a collaboration with Heeger, to examine poly(sulfur-nitride), a crystalline solid, consisting of chains of alternating sulfur and nitrogen atoms, that exhibits metallic conduction [11] down to liquid helium temperatures, and has a superconducting transition at 0.26 K [12].

In the midst of this research, MacDiarmid was traveling in Japan and visited the laboratory of Hideki Shirakawa who was studying the Ziegler–Natta-catalyzed polymerization of acetylene. Standard practice was to use a concentration of the organometallic catalyst at the millimolar level. It is a catalyst after all. These low concentrations led to the infamous ‘insoluble, intractable, black precipitate,’ but Shirakawa had discovered that with concentrations closer to molar, he obtained a shiny ‘metallic’ film coating the wall of the reaction vessel. MacDiarmid returned to Pennsylvania, where he and Heeger quickly arranged to invite Shirakawa for a sabbatical visit.

The pieces were all in place. Scientifically, it was understood that pristine polyacetylene is a Peierls semiconductor, as evidenced by its bond-alternating structure; it was known that charge transfer to molecular donors or acceptors would result in partially filled bands and that the resulting incommensurability of the Fermi wave-vector would destabilize the Peierls phase. The interdisciplinary team had the ideal expertise: the chemists, led by Shirakawa and MacDiarmid, brought their synthetic expertise to the preparation of the polymer films; the physicists, led by Heeger and post-doc C. K. Chiang, brought physical measurement and interpretation of material properties, not just electrical conductivity, but also structural and spectroscopic. Together, they applied vapor-phase doping of molecular acceptors (halogens) and a donor (ammonia).

The publication by Chiang et al. [1] led to a huge surge in interest in ‘synthetic metals.’ In less than a decade, most of the monomer building blocks that we know today had been identified and many procedures for polymeric synthesis had been established. The chemical structures are illustrated in Figure 1.1. (In the nomenclature used in , polyacetylene would be called polyvinylene. This is because some – ‘common’ – names derive from the compound that is polymerized, while others, more correctly according to IUPAC conventions, use the monomeric unit in the product polymer.)