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Conjugated Polymers

A special issue of International Journal of Molecular Sciences (ISSN 1422-0067). This special issue belongs to the section "Materials Science".

Deadline for manuscript submissions: closed (31 January 2011) | Viewed by 84423

Special Issue Editor

1. School of Mechanical, Materials and Mechatronic Engineering, University of Wollongong, Wollongong, NSW 2522, Australia
2. Intelligent Polymer Research Institute (IPRI), University of Wollongong, Wollongong, NSW 2522, Australia
Interests: conjugated polymers; carbon nanotubes; hydrogels; polymer nano-composites; mechanical behaviour; mechanical actuation
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Special Issue Information

Dear Colleagues,

The science and technology of conjugated polymers continues to be a vibrant and exciting research area nearly 30 years after the initial explosion of interest in these materials. In the late 1970s and early 1980s the (re-)discovery of conjugated polymers like polyacetylene, polyaniline and polypyrrole ignited an intense investigation of the properties of these inherently conducting materials. An initial surge of applications were also proposed that included plastic electronics, batteries, sensors and mechanical actuators. Now, nearly 30 years later we are seeing the commercialisation of some of these areas. Issues relating to stability and processing have been tackled to enable mass production of various products.

The science of conjugated polymers continues to be a rich area of interest for fundamental studies in physics and chemistry. We are now able to design and assemble conjugated polymers from the molecular level and through a better understanding of structure – property relationships we can build increasingly sophisticated structures. Many applications for conjugated polymers rely on their facile and reversible electrochemistry, where the polymer can be oxidised and reduced with simultaneous change in properties. The switchable properties is the basis of the application as transistors, sensors, re-chargeable batteries, solar cells, capacitors and even mechanical actuators. The molecular level processes occurring during switching are, however, quite complex and the understanding of charge transport within and between molecules as well as associated ion and solvent exchange with surrounding media are continually being developed. Through this better understanding, we are able to tune the molecular structures and assemble devices from the nano to the macro level for improved performance. Furthermore, we are able to develop devices to operate at smaller and smaller dimensions. Single molecule devices can be achieved with conjugated polymers and applications in nanotechnology and micro-electomechanical systems (MEMS) are well-suited to conjugated polymers.

Finally, the use of conjugated polymers as a link between the electronic world and the biological world is a very exciting new direction. Conjugated polymers have the potential to revolutionise bionics: to enable sensing of biological systems in situ but also to modify biological functions including directing new cell growth for the repair of organs. Conjugated polymers can match the mechanical properties of biological tissue and can be chemically tuned to be biocompatible and potentially biodegradable. While much work still needs to be done in this area, the opportunity for controllable interactions with living tissue through a bio-conjugated polymer is close at hand:

Even after 3 decades of work on conjugated polymers, new areas are emerging and the special joint issue of the journals International Journal of Molecular Sciences, and Materials is a great chance to showcase the recent developments in the science and technology of these fascinating materials.

Prof. Dr. Geoffrey M. Spinks
Guest Editor

Keywords

  • conjugated polymer
  • conductivity
  • electro-activity
  • characterisation
  • plastic electronics
  • solar cells
  • electrochromics
  • actuators
  • batteries
  • capacitor

Related Special Issue

Published Papers (5 papers)

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Research

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346 KiB  
Article
In Vivo Anti-Tumor Activity of Polypeptide HM-3 Modified by Different Polyethylene Glycols (PEG)
by Zhendong Liu, Yinling Ren, Li Pan and Han-Mei Xu
Int. J. Mol. Sci. 2011, 12(4), 2650-2663; https://doi.org/10.3390/ijms12042650 - 19 Apr 2011
Cited by 20 | Viewed by 9216
Abstract
HM-3, designed by our laboratory, is a polypeptide composed of 18 amino acids. Pharmacodynamic studies in vivo and in vitro indicated that HM-3 could inhibit endothelial cell migration and angiogenesis, thereby inhibiting tumor growth. However, the half-life of HM-3 is short. In this [...] Read more.
HM-3, designed by our laboratory, is a polypeptide composed of 18 amino acids. Pharmacodynamic studies in vivo and in vitro indicated that HM-3 could inhibit endothelial cell migration and angiogenesis, thereby inhibiting tumor growth. However, the half-life of HM-3 is short. In this study, we modified HM-3 with different polyethylene glycols (PEG) in order to reduce the plasma clearance rate, extend the half-life in the body, maintain a high concentration of HM-3 in the blood and increase the therapeutic efficiency. HM-3 was modified with four different types of PEG with different molecular weights (ALD-mPEG5k, ALD-mPEG10k, SC-mPEG10k and SC-mPEG20k), resulting in four modified products (ALD-mPEG5k-HM-3, ALD-mPEG10k-HM-3, SC-mPEG10k-HM-3 and SC-mPEG20k-HM-3, respectively). Anti-tumor activity of these four modified HM-3 was determined in BALB/c mice with Taxol as a positive control and normal saline as a negative control. Tumor weight inhibition rates of mice treated with Taxol, HM-3, ALD-mPEG5k-HM-3, ALD-mPEG10k-HM-3, SC-mPEG10k-HM-3 and SC-mPEG20k-HM-3 were 44.50%, 43.92%, 37.95%, 31.64%, 20.27% and 50.23%, respectively. Tumor inhibition rates in the Taxol, HM-3 and SC-mPEG20k-HM-3 groups were significantly higher than that in the negative control group. The efficiency of tumor inhibition in the SC-mPEG20k-HM-3 group (drug treatment frequency: once per two days) was better than that in the HM-3 group (drug treatment frequency: twice per day). In addition, tumor inhibition rate in the SC-mPEG20k-HM-3 group was higher than that in the taxol group. We conclude that SC-mPEG20k-HM-3 had a low plasma clearance rate and long half-life, resulting in high anti-tumor therapeutic efficacy in vivo. Therefore, SC-mPEG20k-HM-3 could be potentially developed as new anti-tumor drugs. Full article
(This article belongs to the Special Issue Conjugated Polymers)
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1211 KiB  
Article
Electrochemical Analysis of Conducting Polymer Thin Films
by Ritesh N. Vyas and Bin Wang
Int. J. Mol. Sci. 2010, 11(4), 1956-1972; https://doi.org/10.3390/ijms11041956 - 26 Apr 2010
Cited by 38 | Viewed by 15512
Abstract
Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material [...] Read more.
Polyelectrolyte multilayers built via the layer-by-layer (LbL) method has been one of the most promising systems in the field of materials science. Layered structures can be constructed by the adsorption of various polyelectrolyte species onto the surface of a solid or liquid material by means of electrostatic interaction. The thickness of the adsorbed layers can be tuned precisely in the nanometer range. Stable, semiconducting thin films are interesting research subjects. We use a conducting polymer, poly(p-phenylene vinylene) (PPV), in the preparation of a stable thin film via the LbL method. Cyclic voltammetry and electrochemical impedance spectroscopy have been used to characterize the ionic conductivity of the PPV multilayer films. The ionic conductivity of the films has been found to be dependent on the polymerization temperature. The film conductivity can be fitted to a modified Randle’s circuit. The circuit equivalent calculations are performed to provide the diffusion coefficient values. Full article
(This article belongs to the Special Issue Conjugated Polymers)
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Review

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372 KiB  
Review
Recent Advances in Conjugated Polymers for Light Emitting Devices
by Mohamad Saleh AlSalhi, Javed Alam, Lawrence Arockiasamy Dass and Mohan Raja
Int. J. Mol. Sci. 2011, 12(3), 2036-2054; https://doi.org/10.3390/ijms12032036 - 21 Mar 2011
Cited by 190 | Viewed by 16641
Abstract
A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now [...] Read more.
A recent advance in the field of light emitting polymers has been the discovery of electroluminescent conjugated polymers, that is, kind of fluorescent polymers that emit light when excited by the flow of an electric current. These new generation fluorescent materials may now challenge the domination by inorganic semiconductor materials of the commercial market in light-emitting devices such as light-emitting diodes (LED) and polymer laser devices. This review provides information on unique properties of conjugated polymers and how they have been optimized to generate these properties. The review is organized in three sections focusing on the major advances in light emitting materials, recent literature survey and understanding the desirable properties as well as modern solid state lighting and displays. Recently, developed conjugated polymers are also functioning as roll-up displays for computers and mobile phones, flexible solar panels for power portable equipment as well as organic light emitting diodes in displays, in which television screens, luminous traffic, information signs, and light-emitting wallpaper in homes are also expected to broaden the use of conjugated polymers as light emitting polymers. The purpose of this review paper is to examine conjugated polymers in light emitting diodes (LEDs) in addition to organic solid state laser. Furthermore, since conjugated polymers have been approved as light-emitting organic materials similar to inorganic semiconductors, it is clear to motivate these organic light-emitting devices (OLEDs) and organic lasers for modern lighting in terms of energy saving ability. In addition, future aspects of conjugated polymers in LEDs were also highlighted in this review. Full article
(This article belongs to the Special Issue Conjugated Polymers)
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1828 KiB  
Review
Conducting Polymer Nanostructures: Template Synthesis and Applications in Energy Storage
by Lijia Pan, Hao Qiu, Chunmeng Dou, Yun Li, Lin Pu, Jianbin Xu and Yi Shi
Int. J. Mol. Sci. 2010, 11(7), 2636-2657; https://doi.org/10.3390/ijms11072636 - 02 Jul 2010
Cited by 264 | Viewed by 24084
Abstract
Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their [...] Read more.
Conducting polymer nanostructures have received increasing attention in both fundamental research and various application fields in recent decades. Compared with bulk conducting polymers, conducting polymer nanostructures are expected to display improved performance in energy storage because of the unique properties arising from their nanoscaled size: high electrical conductivity, large surface area, short path lengths for the transport of ions, and high electrochemical activity. Template methods are emerging for a sort of facile, efficient, and highly controllable synthesis of conducting polymer nanostructures. This paper reviews template synthesis routes for conducting polymer nanostructures, including soft and hard template methods, as well as its mechanisms. The application of conducting polymer mesostructures in energy storage devices, such as supercapacitors and rechargeable batteries, are discussed. Full article
(This article belongs to the Special Issue Conjugated Polymers)
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Graphical abstract

377 KiB  
Review
Emission Characteristics of Organic Light-Emitting Diodes and Organic Thin-Films with Planar and Corrugated Structures
by Mao-Kuo Wei, Chii-Wann Lin, Chih-Chung Yang, Yean-Woei Kiang, Jiun-Haw Lee and Hoang-Yan Lin
Int. J. Mol. Sci. 2010, 11(4), 1527-1545; https://doi.org/10.3390/ijms11041527 - 12 Apr 2010
Cited by 62 | Viewed by 18510
Abstract
In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs) and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design [...] Read more.
In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs) and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design of microcavity structure and layer thicknesses adjustment, optical characteristics can be engineered to achieve high optical intensity, suitable emission wavelength, and broad viewing angles. To increase the extraction efficiency from OLEDs and organic thin-films, corrugated structure with micro- and nano-scale were applied. Microstructures can effectively redirects the waveguiding light in the substrate outside the device. For nanostructures, it is also possible to couple out the organic and plasmonic modes, not only the substrate mode. Full article
(This article belongs to the Special Issue Conjugated Polymers)
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