Polyphenylene Type Polymers

Thermal analysis of polyphenylene, and of benzene, biphenyl, / -terphenyl, and p-quaterphenyl as models, showed that the polymer contained approximately 2 % of defective structures and that these determined the temperature at which thermo-oxidation began. 

The volatile products (which included a dimer) from the thermal degradation of poly (2,6-dimethyl-1,4-phenylene oxide) were analysed by gas chromatography-mass spectrometry. The primary breakdown route involved a Fries-type rearrangement of the polymer chain. The electron-induced fragmentation of the dimeric product has been studied in detail.  

The volatile products from thermal degradation of poly(2-methyl-l,4-phenylene oxide), poly(2,5-dimethyl-l,4-phenylene oxide), and poly(l,4-phenylene oxide)have been analysed by gas chromatography-mass spectrometry. The methyl substituted 

Maravigna, G. Montaudo, and E. Scamporrino, Makromol. Chem., 1980, 181,2161. 

The kinetics of thermo-oxidation of poly(phenylene sulphide) have been studied by thermoanalytical techniques and the products of thermal decomposition of polysulphonatesand of polysulphones analysed either by pyrolysis in the ion source of a mass spectrometer or by combined pyrolysis-gas chromatography-mass spectrometry. 

Poly(hydroxy hydroquinones) break down by oxidation of hydroquinone groups to quinones, followed by dehydroxylation and finally by decomposition of quinone rings. Two competing processes, heterolytic and homolytic, are operative in the degradation of polyisocyanurates the former dominates at low temperatures and the latter becomes steadily more important as the temperature is raised.  

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T. Yamamoto, Y. Hayashi, and A. Yamamoto, A novel type of polycondensation utilizing transition metal-catalyzed C-C coupling. I. Preparation of thermostable polyphenylene type polymers, Bull. Chem. Soc. Jpn., 51(7) 2091-2097, July 1978. 

Fig. 68. Loss in weight of various polyphenylene-type polymers after heating in vacuo for 2 h at different temperatures [276]. A, poly-p-2,3,5,6-tetramethylphenylene methylene B, poly-9,10-anthrylene ethylene C, poly-p-2,5-dimethoxyphenylene ethylene D, poly-p-2,5-dimethylphenylene methylene E, poly-p-phenylene ethylene F, poly-p-2,3,5,6-tetramethylphenylene ethylene G, poly-2,6-naphthylene ethylene H, poly-p,p -diphenylene methylene I, poly-m-phenylene J, poly-p-phenylene.

V. Korshak, I. Gribova and A. Krasnov. Tribochemical reactions and wear resistance of polymers of the polyphenylene type. Intern. Conf. Wear of Materials, Houston, Texas, 1987, Vol. 1, No. 1, pp. 435-438. 

Grimsdale, A. C. and MUllen, K.i Polyphenylene-type Emissive Materials Poly(para-phen)d-ene)s, Polyfiuorenes, and Ladder Polymers. Vol. 199, pp. 1-82. 

Polyphenylene-type Emissive Materials Poly(para-phenylene)s, Polyfluorenes, and Ladder Polymers... 

Many other types of polymer have been prepared which exhibit semiconductivity. All obey the equation a = a0exp — E/kT. These include xanthene polymers (109, 110), polymerized phthalocyanines (111, 112), epoxides and polydiketones (86, 113), polypentadienes (114), polydicyanoacetylenes (115), polyvinylferrocene and substituted ferrocene (116, 117, 118, 119), polymeric complexes of tetracyanoethylene and metals (120), poly(vinyl chloride) and poly(vinylidene chloride) (121), polyvinylene and polyphenylene (122) and poly(Schiff s bases) (123, 124). 

Polymer nanotubes composites are now extensively studied. Indeed, one may associate the properties of the polymer with those of nanotubes. This is the case of the mechanical reinforcement of standard polymer for example, but also one can take advantage of the specific electronic properties of the nanotubes. Therefore, we prepared composites with either saturated polymers like polymethylmethacrylate and MWNTs [27]. The electrical conductivity of these compounds as a function of the nanotube content exhibits for example a very low percolation threshold, (a few % in mass) and therefore they can be used as conducting and transparent layers in electronic devices such as Light Emitting Diodes (LEDs). Another type of composite that we have studied is based on the use of a conjugated polymer, polyphenylene-vinylene (PPV) known for its photoluminescence properties and SWNTs. We prepared this composite by mixing SWNTs to the precursor polymer of PPV. The conversion into PPV was subsequently performed by a thermal treatment at 300°C under dynamical vacuum [28],... 

Preparation and characterization of highly branched aromatic polymers, polyphenylenes, polyesters, polyethers, and polyamides, were reviewed. These polymers were prepared from condensation of AB -type monomers, which gave noncrosslinked, highly branched polymers. The polymer properties are vastly different compared to their linear analogs due to their resistance to chain entanglement and crystallization. 

Scherf and Mullen prepared (Scheme 47) the ladder-type polyphenylene (LPPP, 5) with methine bridges [126-129], via a poly(diacylphenylene-co-phenylene) precursor copolymer 103 obtained by an AA-BB type Suzuki polycondensation. The key step is the polymer analogous Friedel-Crafts ringclosing reaction on the polyalcohol 104, obtained by the reduction of 103. This was found to proceed quickly and smoothly upon addition of boron-trifluoride to a solution of 104 in dichloromethane. The reaction appeared to be complete by both NMR and MALDI-TOF analysis, indicating the presence of less than 1% of defects due to incomplete ring closure. LPPPs with num-... 

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