Oligo- and Poly phenylene s

The synthesis-driven approach towards material science can be applied to create oligomers and polymers with optimized properties, e.g. maximized carrier mobilities and electrical conductivities or high photo- and electroluminescence quantum yields. It becomes obvious, however, that the ability to synthesize structurally defined 7i-architectures is the key to these high performance materials. 

Besides the classical search for linear, one-dimensional electronically active materials, synthetic approaches are now also focussed on the generation and characterization of two- and three-dimensional structures, especially shape-persistent molecules with a well-defined size and geometry on a nanometer-scale. It is therefore timely and adequate to extend concepts of materials synthesis and processing to meet the needs defined by nanochemistry since the latter is now emerging as a subdiscipline of material sciences. 

A large part of organic and macromolecular chemistry starts with the chemical functionalization of benzene, and benzene units serve as building blocks for important polymers. Naturally, benzene-based aromatic materials also represent an important subclass of 7i-conjugated architectures. Despite some synthetic difficulties related to the generation of structurally well-defined oligo- and poly(phenyl- 

Edited by G. Hadziioannou and P. F. van Hutten Copyright 1999 WILEY-VCH Verlag GmbH, Weinheim ISBN 3-527-29507-0 

Poly(p-phenylene)s, PPPs, constitute the prototype of rigid-rod polymers and are currently being intensively investigated [1], The key role of PPPs follows from their conceptually simple and appealing molecular structure, from their chemical stability, and from their superior physical properties [2], In turn, this is the result of important advances made in aromatic chemistry over the last few years. The following section gives an overview of the most common methods to generate poly(p-phenylene)s via different synthetic approaches. 

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Ladder-Type Oligo- and Poly(para-phenylene)s.177... 

Based on the results of the synthesis of oligo- and poly(para-phenylene)s PPPs (see Sects. 2.1-2.3) several investigators have studied the generation of other oligo- and polyarylenes. 

H. Meier, H. Kretzshmann, and M. Lang, Synthesis of 2-alkoxy substituted oligo and poly( 1,4-phenylene-ethylene)s and 2-arylbenzo[/ ]furanes by applying the Siegrist reaction,5. Pra/c Chem. 336. 1 (1994). 

Solid polymer electrolytes have been actively pursued as a major contribution to the development of high-energy density batteries, particularly lithium secondary batteries. The poly(p-phenylene)s substituted with oligo(oxymethylene) side chains and blends of these novel polymers with lithium salts are achieved by biaryl coupling of benzene-1,4-diboronic acids (Fig. 4). ° OctapoIy(p-phenylene) functions as the artificial ion channel which specially recognizes (bio)membranes by their thickness (Fig. 5). ... 

Triblockcopolymers derived from a central block of PES and two wings of poly(phenylene oxide) were also reported [57]. For this purpose oligo(ether sulfone)s were synthesized with an excess of DFDPS, so that two C-F endgroups were obtained (37). These oligomers were then polycondensed with poly(phenylene oxide)s having one trimethylsiloxy endgroup whereby CsF served as catalyst (38). Multiblock copolymers... 

Optical absorption, PL and EL in poly[(tetraalkyldisilanylene)-/>-oligophenylene]s (PDSiOP) were found to depend on the length of the oligo-phenylene and not on the length of the short alkyl substituents, such as methyl and ethyl groups.76... 

A rigid backbone was used by Wegner to build ion-conductive PEO-based polymers [63]. 01igo(ethylene oxide) chains were grafted from poly(p-phenylene) as shown in Fig. 6. The mixtures of polymers 5 and lithium salts show conductivities in the order of 10-6 Son 1 at ambient temperature. The ionic conductivities can be improved to the order of 10-5 S cm-1 by plasticization of the materials with oligo(ethyleneglycol)-dimethylether. 

Zhou G J, Wang S F, Zhang Y, Zhuang Q X and Han Z W (2008) In situ preparation and continuous fiber spinning of poly(p-phenylene benzobisoxazole) composites with oligo-hydroxy-amide-functionalized multi-walled carbon nanotubes, Polymer 49 2520-2530. 

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