High-molecular-weight poly phenylene

Combining whole-cell biocatalysis and radical polymerization, researchers at Imperial Chemical Industries (ICI) published a chemoenzymatic route to high-molecular-weight poly(phenylene) [86], This polymer is used in the fibers and coatings industry. However, since it is practically insoluble, the challenge was to make a soluble polymer precursor that could first be coated or spun, and only then converted to poly(phenylene). The ICI process starts from benzene, which is oxidized by Pseudomonas putida cells to cyclohexa-3,5-diene-l,2-diol (see Figure 5.17). The... 

The rate constant of the electron-transfer step was Increased several times for the catalyst (1). This agreed with the result that 1 acted as an effective catalyst for the oxidative pol)rmer-ization of dimethylphenol to yield high molecular weight poly-(phenylene oxide) (7). 

High-molecular-weight poly(phenylene ether) with an intrinsic viscosity (IV) of 0.70 dlg can be produced in a methylene chloride solution without precipitation of the catalyst complex. The catalyst is then removed by extraction with either aqueous acid, which removes both the amine and metal ion catalyst components, or by treatment with a chelating agent, such as ethylenediamine tetraacetic acid. ... 

L. Lutsen, P. Adriaensens, H. Becker, A.J. Van Breemen, D. Vanderzande, and J. Gelan, New synthesis of a soluble high molecular weight poly(arylene vinylene) poly[2-methoxy-5-(3,7-dimethyloctyloxy)-p-phenylene vinylene]. Polymerization and device properties, Macromolecules, 32 6517-6525, 1999. 

The preparation of the related high molecular weight poly-1.4-phenylene sulfide has been accomplished by heating />-bromothio-phenolate salts in pyridine at 250° C (57). The commercially available polyethersulfones are reported to be prepared by condensation of 4.4 -dichlorodiphenyl sulfone with salts of biphenols in solvents such as dimethylsulfoxide at 150° C. The work of Bacon and Hill would suggest that both of these reactions might be carried out at considerably lower temperatures with copper (I) salts as catalysts. In addition, it has been demonstrated that copper (I) acetylides react quantitatively with aromatic iodides to yield tolanes (15, 77) therefore this reaction should also be the basis for a similar polymer forming reaction. 

In 1959, Hay and coworkers described the first efficient route for the production of high-molecular-weight poly-2,6-disubstituted-l,4-phenylene ethers [10]. For instance, the reaction of 2,6-dimethylphenol (DMP) in the presence... 

Louwet, F, Vanderzande, D., Gelan, J., 1995. A general synthetic route to high-molecular-weight poly(p-xylylene)-derivatives—a new route to poly(p-phenylene vinylene). Synth. Met. 69, 509-510. 

Silarylene-disiloxane polymers, which exhibit a wide range of physical properties depending on their composition and structure, have received considerable academic and industrial interest for nearly 50 years.One of the prominent properties of silarylene-disiloxane polymers is their excellent thermal stability. The typical methods employed for the synthesis of silarylene-siloxane polymers are the selfpolycondensation of arylenedisilanols or the copolycondensation of arylenedisila-nols with other bifunctional compounds. We found that the easily accessible 1,4-bis(dimethylsilyl)benzene (p-BSB) could react with water in the presence of a catalytic amount of transition metal (Pd, Pt, Rh, etc.) compounds at room temperature to afford high molecular weight poly[(oxydimethylsilylene)(l,4-phenylene) (dimethylsilylene)] with the evolution of H2 as the only by-product, as shown in Scheme 4.6. ... 

Recently, Ballard and co-workers discovered a novel path to prepare linear polyphenylene, based on the polymerization of derivatives of 5,6-dihydroxycyclohexa-1,3-diene. The advantage of this method is that the diene polymer remains soluble in a variety of solvents, because of the presence of solubilizing groups, such as ester functions. Because of this, molecular weight determinations can be made before the final pyrolysis to remove the attached groups. Ballard et al. reported that the final product is a high molecular weight poly(p-phenylene). 

Delsman ER, Schoenmakers GJ. High molecular weight poly(2,6-dimethyl-l,4-phenylene ether) and process therefor US Patent 8 507 636, assigned to Sabic Innovative Plastics IP B.V., NL 2013. 

Gagnon, D.R., et al. 1987. Synthesis, doping, and electrical conductivity of high molecular weight poly(p-phenylene vinylene). Polymer 28 567. 

Allegations that poly(phenylene sulfide) was originally prepared by the reaction of benzene and sulfur with AlCl are a result of creative reading of the literature. Formation of high molecular weight poly(arylene sulfides) in the presence of AlCl is highly unlikely because the latter catalyzes both polymerization and degradation reactions. 

PBI fiber is dry spun from a solution of high molecular weight poly-[2,2 -(m-phenylene)-5,5 -bibenzimidazole]. Here, prepolymer is an intermediate which is not isolated. A schematic of Celanese s PBI fiber process is shown in FIGURE 4. 

The oxidative polymerization of substituted phenols to poly(phenylene oxides is another example where a polymeric chain is formed by carbon-heteroatom coupling. " Thus, the reaction of 2,6-dimethylphenol with oxygen, in the presence of a copper-amine complex, yields high molecular weight poly(2,6-dimethyl-l,4-phenylene oxide). 

The polymerization of 1,3-cyclohexadiene can be initiated by free radicals, Ziegler-Natta catalysts, and transition metal catalysts, both cationically and anionically [413-416]. The synthesis of high-molecular-weight poly (1,3-cyclohexadiene) containing 1,4-structures (62), especially has been of great interest, as unbranched poly(/ -phenylenes) are accessible from it after dehydrogenation [417-419]. 

The siloxy compound of cyclohexadiene is able to polymerize as shown in eq. (19.51). However, it is difficult to dehydrogenate the siloxy polymers by heating, but their acetoxy compounds are able to be dehydrogenated at 310-340 ""C to afford a high molecular weight poly-p-phenylene [95,95a]. 

Harris and coworkers reported the synthesis of the monomer 4,4 -(l,4-phenylene)bis(2,6-diphenyl-pyrybum tetrafluoroborate) 41 and a novel class of high molecular weight poly(pyridinium tetrafluoroborate)s 42 salts (PPS) (Scheme 16). These phenylated heterocycUc polymers are well known for their excellent solubility in otganic solvents, film-forming abibty, thermal stability, ionic conductivity, ion-exchange membrane formation, and chemical stability. 

Poly(sulfonium cation) for the Synthesis of High-Molecular-Weight Pofy(phenylene... 

The oxidative polymerization reaction was found to be a general reaction and linear high molecular weight polymers and diphenoquinones were prepared from other 2,6-dialkylphenols. If the substituents are bulky, e.g. a t-butyl group, only the diphenoquinone is formed. We were also able to synthesize high molecular weight poly (2,6-diphenyl-1,4-phenylene oxide) (P3O, 5) from 2,6-diphenylphenol 4. (Scheme 2)... 

Poly(arylene vinylenes). The use of the soluble precursor route has been successful in the case of poly(arylene vinylenes), both those containing ben2enoid and heteroaromatic species as the aryl groups. The simplest member of this family is poly(p-phenylene vinylene) [26009-24-5] (PPV). High molecular weight PPV is prepared via a soluble precursor route (99—105). The method involves the synthesis of the bis-sulfonium salt from /)-dichloromethylbenzene, followed by a sodium hydroxide elimination polymerization reaction at 0°C to produce an aqueous solution of a polyelectrolyte precursor polymer (11). This polyelectrolyte is then processed into films, foams, and fibers, and converted to PPV thermally (eq. 8). 

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