Polyphenylene and Related Polymers

Kaeriyama et al.163) obtained insulating films of polyphenylene by electrochemical polymerization in nitromethane solution containing AlClj. Again, the films could be doped only to rather low conductivities and there was evidence of considerable structural irregularity. The first reports of a highly conducting film appear to be 

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Due to limited space, only representative examples of polyphenylenes and related polymers synthesized by SPC are described in this section. More comprehensive details are provided in recent reviews [1, 3]. 

Suzuki Reaction Polymerizations. The Pd-catalyzed cross-coupling reaction of an organic electrophile and an organoboron compound in the presence of base has been extensively applied to the synthesis of polyphenylenes and related polymers. Well defined structures are obtained as a result of the regiospecificity of the Suzuki reaction (84) (230). The solubility of the polymers is commonly enhanced by the presence of alkyl or other types of substituents [for example see equations 85-87 (231,232,233 respectively and 254)]. 

This review summarizes our work at the University of Bayreuth over the last few years on improving the electret performance of the commodity polymer isotactic polypropylene (Sect. 3) and the commodity polymer blend system polystyrene/polyphenylene ether (Sect. 4) to provide electret materials based on inexpensive and easily processable polymers. To open up polymer materials for electret applications at elevated temperatures we concentrated our research on commercially available high performance thermoplastic polyetherimide resins and synthesized several fluorinaled polyetherimides to identify structure-property relations and to improve further the performance at elevated temperatures (Sect. 5). 

Following an initial report by Kim etal. [20, 54] of a branching factor for a hb polyphenylene, Frechet et al. [55] later deflned for the first time the DB for describing hb polymers. By adopting the structure of an ideally branched dendrimer possessing only dendritic and terminal units, it was possible to relate the sum of dendritic and terminal units to the total sum of all repeating units, by considering linear units as units which decreased the DB (Equation 24.1) ... 

Among the polyphenylene-based materials highly emissive PFs have received particular attention due to their extraordinary properties in device applications as originally demonstrated by Bradley [74,76-78]. In addition to the wide variety of synthetic routes allowing for the synthesis of differently substituted homopolymers as well as copolymers, PFs display attractive optical and electronic properties which make them ideal model systems for studying relevant structure to property relations in conjugated polymers as shown by Cadby et al. [77,116]. For this reason different properties which are related to the molecular structure as well as to intrachain order effects of the polymer shall be discussed in the following. 

In Table 4.3, critical temperatnre data related to polymers are quoted. These include heat distortion temperatnre, brittleness temperature, melt temperature, mold temperature, recommended maximnm operating temperature, and performance at low temperatnre. Heat distortion temperatnres, for example, range from 10-50 MPa (low-density polyethylene, polynrethane) to above 250 MPa (polyphenylene sulfide, urea formaldehyde-diallyl phthalate, polyether ether ketone, and polyamide-imide). 

Cyclic voltammetric studies of the oiganoiron polyphenylene sulfide (8a) were undertaken in DMF and propylene carbonate." The influence of solvents on the reversibility of the redox waves of these complexes is related to their coordinating ability. " It was found that the polymer adsorbed to the working electrode in DMF but not in propylene carbonate." The half-wave potential of 8a in propylene carbonate at -30°C was 0.85 V using a scan rate of 2 V/s. This cychc voltammogram is shown in Figure 9. 

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