Introduction to Conjugated Polymers

Polymer Design Principles for Solid-State Sensors 208 

Thin-film conjugated polymer sensors and aggregation 208 

Ultra-trace TNT Detection with Operable Devices 213 

Future material and transduction improvements - lasing sensors 218 

Aspects of Explosives Detection M. Marshall andJ.C. Oxley (Editors) 

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Introduction to Conjugated Polymers, Electropolymerization, tmd Solubility Ptirameters 137... 

Since the pioneering work of Tang and VanSlyke [128], LEDs made with organic materials (OLEDs) have rapidly attracted interest in the scientific literature, industry and the media. The potential use of OLEDs in flat panel displays has encouraged numerous scientific and industrial efforts to realize this new technology. The introduction of conjugated polymers as emitting materials by Friend and co-workers [129], which led to polymeric OLEDs or PLEDs, was one of the milestones in the development of OLEDs. 

Introduction of side chains will generally increase the solubility of the polymers but usually disrupt the conjugation along the polymer backbone. By properly choosing the side chains and linker, it is possible to prepare polymers with desired conjugation and solubilities.40... 

The introduction of bulky side chains that contain adamantyl groups to poly(p-phenylenevinylene) (PPV), a semiconducting conjugated polymer, decreases the number of interchain interactions. This action will reduce the aggregation quenching and polymer photoluminescence properties would be improved [93]. 

As we will see in Section 5, it is not a straightforward matter to obtain conjugated polymers with a high content of pendent radicals either chemical introduction of radicals into polymers is inefficient or radical centres cannot be kept intact during polymerization. A possible way out of this problem has been proposed by Fukutome, namely, doping of closed-shell cross-conjugated polymers to generate the open-shell centres. The polaronic interaction in these systems has been discussed (Fukutome et al., 1987). 

Polymeric micelles are mostly small (10-100 nm) in size and dmgs can be incorporated by chemical conjugation or physical entrapment. For efficient delivery activity, they shonld maintain their integrity for a sufficient amount of time after injection into the body. Most of the experience with polymeric micelles has been obtained in the field of passive targeting of anticancer drugs to tumours [33]. Attachment of antibodies or sugars, or introduction of a polymer sensitive to variation in temperature or pH has also been stndied [32]. 

An extensive review of the synthesis of rc-conjugated polymers is presented using a tutorial approach to provide an introduction to the field intended for the undergraduate student and the experienced chemist alike. The many synthetic methodologies that have been used for the synthesis of conjugated polymers are outlined for each class of polymers with a focus on research from the 1990s. The effect of structure on electrical properties is detailed. Specific systems reviewed include the polyacetylenes, polyanilines, polypyrroles, polythiophenes, poly(arylene vinylenes), and polyphenylenes. 

In this instance, Ziegler-Natta polymerization yields a soluble, linear polymer 2, containing a six-membered cyclic ring fused at each repeat unit. Unfortunately, this polymer undergoes isomerization to form a non-conjugated polymer, disrupting the electronic properties of the backbone [31]. It was found that this isomerization could be prevented by the introduction of heteroatom functionality into the diyne architecture, as exemplified by the polymerization of propiolic anhydride 3, which yielded a stable polymer 4 as shown in Scheme 11 [32]. 

Many basic texts on polymer science are available. The books by Billmeyer (1971), Brydson (1999) and Boyd and Phillips (1993) provide a wide coverage of the subject. Nicholson (1997) provides a useful elementary introduction to polymer chemistry. The text by Grosberg and Khokhlov (1997) provides an excellent introduction to the basics of polymer properties and behaviour in relation to their underlying molecular structure. The proceedings of the 81st Nobel Symposium, Salaneck, Lundstrom and Ranby (1993), gives an overview of the science of conjugated polymers. 

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