Chromogenic Phenomena in Polymers

Chromogenic phenomena, exemplified by electrochromism, photochromism, thermochromism, piezochromism, and magnetochrom- ism, (i.e., color changes ...
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Downloaded by 91.242.217.117 on July 4, 2016 | http://pubs.acs.org Publication Date: August 17, 2004 | doi: 10.1021/bk-2005-0888.pr001

Preface Chromogenic phenomena, exemplified by electrochromism, photochromism, thermochromism, piezochromism, and magnetochromism, (i.e., color changes induced respectively by applied electrical, optical, thermal, pressure, and magnetic fields), provide many mechanisms that facilitate real-time tunability of the optical properties of materials. O f these, photochromism and electrochromism have been more widely investigated in polymeric and organic materials. They currently find some commercial and defense applications such as selfadjusting sunglasses, filters in optical sensors, color-tunable coatings and paints, thermographic recording media in medical applications, selfadjusting car rearview mirrors, and color-switching clothing. However, the great promise of electrochromic, photochromic, and other chromogenic materials in applications ranging from large-area information displays, ultrahigh density optical memories, holographic recording, smart windows, "intelligent" materials systems, and photoresponsive transducers to large-area color-tunable wallpaper are yet to be fully realized. The challenges and barriers to achieving these large-scale and high-impact technological applications include the stability of the materials under long-term cycling, the speed with which optical changes can be effected, the amount of energy required to achieve optical tunability, satisfactory color contrasts, and the processability of the chromogenic materials into suitable forms, such as conformai coatings, multilayer films, and ordered nanoporous solids. These challenges are being addressed through the targeted synthesis and detailed structural understanding of chromogenic effects in polymers, the fundamental understanding of the physical and chemical mechanisms of coloration and the coloration dynamics, and the design and fabrication of devices and systems incorporating the materials. Novel classes of chromogenic polymers have also emerged in the past several years and are currently of great research and technological interests, including tunable light emitting polymers and devices that are promising for flexible displays; polymers with tunable

xi Jenekhe and Kiserow; Chromogenic Phenomena in Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 2004.

Downloaded by 91.242.217.117 on July 4, 2016 | http://pubs.acs.org Publication Date: August 17, 2004 | doi: 10.1021/bk-2005-0888.pr001

selective reflection spanning the visible and near IR; and polymer composites having one-, two-, or three-dimensional photonic band gaps. Self-assembly approaches to the synthesis, processing, patterning, and device applications of chromogenic polymers and hybrid materials have also emerged as major areas of research in the past several years. Nanostructured polymer systems having tunable electronic, optoelectronic, and photonic properties represent excellent model systems for exploring a range of new concepts of intelligent-self-repairing materials and systems, intelligent sensors-detectors, nanoelectromechanical systems, and various multifunctional devices. Our goal in organizing the symposium was to provide an international forum to discuss important scientific and technological advances and future prospects in the broad field of chromogenic phenomena in polymers. The chapters included in the book were nearly all based on the invited presentations at the symposium. The main topics include electrochromic polymers and devices for the visible and IR; electroluminescent polymers and tunable emission; photochromic and stimuli-responsive polymers; optically switchable materials and devices; photonic band-gap materials; tunable multifunctional optical materials; bioinspired and biomimetic chromogenic materials; supramolecular chromism and self-assembly approaches to tunable optical materials; chromic polymers for chemical sensors and biosensors; photonic polymer-inorganic nanocomposites; mechanochromic and nanophotonic polymers; and polymers for imaging and high-density data storage. A broad multidisciplinary group of researchers that include chemists, physicists, engineers, and materials scientists from academia, government, and industry participated in the symposium and contributed chapters to this book. We expect chemists and materials scientists who are interested in the synthesis and characterization of polymers with tunable electronic, optoelectronic, and photonic properties will find this book useful, along with physicists, biochemists, and engineers who are interested in the properties and device applications of chromogenic materials. We acknowledge the U.S. Army Research Office for the generous financial support that enabled broad participation at the symposium and in the preparation of this book. We thank the referees for their important help in the critical assessment of the manuscripts and the authors for their contributions. We also thank John D. Wind and Jeanie Comstock at the University of Washington for assistance in the editing process. Finally, the help and patience of Stacy VanDerWall and Robert

xii Jenekhe and Kiserow; Chromogenic Phenomena in Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 2004.

W. Hauserman in acquisitions and Margaret Brown in editing and production of the A C S Books Department were essential in the publication of the book.

Samson A. Jenekhe

Downloaded by 91.242.217.117 on July 4, 2016 | http://pubs.acs.org Publication Date: August 17, 2004 | doi: 10.1021/bk-2005-0888.pr001

Department of Chemical Engineering Benson Hall, Box 351750 University of Washington Seattle, WA 98195-1750 [email protected] (email)

Douglas J. Kiserow Branch Chief, Polymer Chemistry U.S. Army Research Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 [email protected] (email)

xiii Jenekhe and Kiserow; Chromogenic Phenomena in Polymers ACS Symposium Series; American Chemical Society: Washington, DC, 2004.