Heterocyclic polymers, reviews

Ubichromenol synthesis, 3, 752 Ugi reaction, 5, 830 Uliginosin B, bromo-molecular dimensions, 3, 621 Ullman and Fetvadjian synthesis quinolines, 2, 477 Ullman synthesis acridines, 2, 470-benzacridines, 2, 470 Ultraviolet light absorbers in polymers, 1, 397-398 Ultraviolet spectroscopy heterocyclic compounds reviews, 1, 78... 

Chemistry, reaction mechanisms, and properties have been extensively reviewed.4,5,10-20 Hie present chapter deals witii only one type of fully cyclized aromatic heterocyclic polymers die high-molecular-weight linear polymer witii a special emphasis on die synthesis and structure—property relationships for specific applications. 

While several preparative routes may exist for the synthesis of a given heterocyclic polymer, we have attempted to portray the method that has received the most common usage. Throughout our discussion we have attempted to reference and supplement the most recent and definitive texts, monographs and reviews that exist on a given subject. In addition, whenever possible we have indicated what particular properties and attending applications are accrued by inclusion of the heterocycle in the polymer framework. 

Heterocycle-forming polymerization reactions have been the most extensively reviewed of the three methods for obtaining heterocyclic polymers. A series of monographs are available that cover the literature through 1971 quite well (B-72MI11109). These monographs have served to provide an excellent foundation for our efforts. Whenever possible, we have cited more recent references, especially any reviews. It is the purpose of this section to depict succinctly the rich variety of chemistry that has been employed to form heterocyclic polymers of this type. This section, then, is a capsule summary of most of the heterocycles that have been generated concomitant with formation of a polymer. 

The field of organic conductors has been extensively reviewed (B-77MI1300, 78ANY25, B-78MI11300, 78MI11302, 79ACR79) and no attempt is made here to describe the synthesis and properties of known materials. Molecular conductors of the doped polymer type have been excluded since these are neither intrinsic conductors nor heterocyclic. A review of the principal requirements for the molecular and crystal structures as currently understood is presented as an introduction to the field of organic conductors. 

Abstract Recent developments in the microwave-assisted synthesis of heterocycles are surveyed with the focus on diversity-oriented multi-component and multi-step one-pot procedures. Both solution- and solid-phase as well as polymer-supported methodologies for the preparation of libraries of heterocycles are reviewed. Advantages of microwave dielectric heating are highlighted by comparison with conventional thermal conditions. 

Work in our laboratory in the past few years has been concerned with the use of acetylene chemistry, both to aid the processing of aromatic heterocyclic polymers and to pro-, vide such materials a method by which they could become tougher and more durable in structural applications. The most attractive feature of the acetylenic carbon carbon triple bond is its capability to undergo various ionic and free radical addition reactions, leading to highly fused thermally stable aromatic systems. This paper will review our work on acety-lene containing aromatic heterocyclic polymers with respect to synthesis and characterization, as well as some already determined mechanical properties as composites and adhesives. 

Polyfarylene vinylene)s form an important class of conducting polymers. Two representative examples of this class of materials will be discussed in some detail here. There are poly(l,4-phenylene vinylcne) (PPV) 1, poly(l,4-thienylene viny-lenc) (PTV) 2 and their derivatives. The polymers are conceptually similar PTV may be considered as a heterocyclic analog of PPV, but has a considerably lowci band gap and exhibits higher conductivities in both its doped and undoped stales. The semiconducting properties of PPV have been shown to be useful in the manufacture of electroluminescent devices, whereas the potential utility of PTV has yet to be fully exploited. This account will provide a review of synthetic approaches to arylene vinylene derivatives and will give details an how the structure of the materials relate to their performance in real devices. 

Cyclophosphazenes are a fascinating group of inorganic heterocyclic compounds whose chemistry is multi-faceted, well developed and reasonably well understood. They are closely related to the linear poly-phosphazenes this relationship is unlike any other existing between ring-polymer systems. Although cyclic siloxanes and polysiloxanes have a close interrelationship, the number and types of cyclophospha-zene derivatives that are known, together with their exact counterparts in polyphosphazenes, underscore the utility of cyclophosphazenes as models for the more complex polyphosphazenes. The literature on cyclophosphazenes has appeared earlier in the form of books (1,2), chapters of books (3-5), authoritative compilations of data (6,7), and several reviews (8-21). The current literature on this subject is reported annually in the Specialist Periodic Reports published by the Royal Society of chemistry (22). This review deals mostly with chlorocyclo-... 

This review deals with the synthesis of PAEs. Described are the developments this field has undergone in the last 4 years. A comprehensive review on PAEs appeared in 2000 (Table 1, entry 1) [Ij. Several other noteworthy PAE reviews are those of Yamamoto (Table 1, entries 7,8) that cover mostly heterocyclic representatives and Pinto and Schanze s review (Table 1, entry 6) about water-soluble conjugated polymers. The specific area of dialkyl PPEs and their synthesis by alkyne metathesis has been reviewed recently (Table 1, entries 2-4)... 

Recent work on the synthesis, structure and some properties of macromolecules bearing furan rings is discussed. Two basic sources of monomers are considered, viz. furfural for monomers apt to undergo chain polymerization and hydroxymethylfurfural for monomers suitable for step polymerization.Within the first context, free radical, catiomc and anionic systems are reviewed and the peculiarities arising from the presence of furan moieties in the monomer and/or the polymer examined in detail. As for the second context, the polymers considered are polyesters, polyethers, polyamides and polyurethanes. Finally, the chemical modification of aU these oligomers, polymers and copolymers is envisaged on the basis of the unique reactivity of the furan heterocycle. 

A change of architecture is another route that enables diversification of the properties of aliphatic polyesters. This review will focus on star-shaped, graft, macrocyclic, and crosslinked aliphatic polyesters. It must be noted that the ROP of lactones has been combined with several other polymerization mechanisms such as ROP of other heterocyclic monomers, ionic polymerization, ROMP, and radical polymerization. Nevertheless, this review will not cover these examples and will focus on polymers exclusively made up of poly(lactone)s. 

The reactivity of substituents on the heterocyclic and the carbocyclic nuclei of dibenz[6,/]azepines has been reviewed (74CRV101). Polymers of iV-acryloyl-10,11 -dihy-drodibenz[6,/]azepines have been prepared (78MI51603). 

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