http://www.mdpi.com/journal/ijms/special_issues/conjugated-polymers-ijms/ 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 Related Special Issue Conjugated Polymers in Materials {snippet name="submission_info"} http://www.mdpi.com/1422-0067/12/4/2650/ 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. http://www.mdpi.com/1422-0067/12/4/2650/ Tue, 19 Apr 2011 00:00:00 CEST International Journal of Molecular Sciences 2011-04-19 12 4 Article 2650 2663 1422-0067 In Vivo Anti-Tumor Activity of Polypeptide HM-3 Modified by Different Polyethylene Glycols (PEG) 2011-04-19 doi: 10.3390/ijms12042650 Zhendong Liu Yinling Ren Li Pan Han-Mei Xu http://www.mdpi.com/1422-0067/12/3/2036/ 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. http://www.mdpi.com/1422-0067/12/3/2036/ Mon, 21 Mar 2011 00:00:00 CET International Journal of Molecular Sciences 2011-03-21 12 3 Review 2036 2054 1422-0067 Recent Advances in Conjugated Polymers for Light Emitting Devices 2011-03-21 doi: 10.3390/ijms12032036 Mohamad Saleh AlSalhi Javed Alam Lawrence Arockiasamy Dass Mohan Raja http://www.mdpi.com/1422-0067/11/7/2636/ 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. http://www.mdpi.com/1422-0067/11/7/2636/ Fri, 02 Jul 2010 00:00:00 CEST International Journal of Molecular Sciences 2010-07-02 11 7 Review 2636 2657 1422-0067 Conducting Polymer Nanostructures: Template Synthesis and Applications in Energy Storage 2010-07-02 doi: 10.3390/ijms11072636 Pan Qiu Dou Li Pu Xu Shi http://www.mdpi.com/1422-0067/11/4/1956/ 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. http://www.mdpi.com/1422-0067/11/4/1956/ Mon, 26 Apr 2010 00:00:00 CEST International Journal of Molecular Sciences 2010-04-26 11 4 Article 1956 1972 1422-0067 Electrochemical Analysis of Conducting Polymer Thin Films 2010-04-26 doi: 10.3390/ijms11041956 Vyas Wang http://www.mdpi.com/1422-0067/11/4/1527/ 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. http://www.mdpi.com/1422-0067/11/4/1527/ Mon, 12 Apr 2010 00:00:00 CEST International Journal of Molecular Sciences 2010-04-12 11 4 Review 1527 1545 1422-0067 Emission Characteristics of Organic Light-Emitting Diodes and Organic Thin-Films with Planar and Corrugated Structures 2010-04-12 doi: 10.3390/ijms11041527 Wei Lin Yang Kiang Lee Lin