Biphenylene Polymer

HIGH MOLECULAR WEIGHT AROMATIC BIPHENYLENE POLYMERS BY NICKEL COUPLING OF ARYL DICHLORIDES... 

High Molecular Weight Aromatic Biphenylene Polymers by Nickel Coupling... 

In 1996, Wegner et al. published the synthesis of poly(oligophenylenevinyle-ne)s (96), consisting of biphenylene-, terphenylene- and quinquephenylene moieties as aromatic building blocks, via Suzuki-type aryl-aryl cross coupling of AA/BB-type monomers [121]. By judicious choice of the arylene moieties, the optical properties of the resulting polymers can be tailored within a wide range. 

Cured ethynyl-terminated ester oligomers prepared from the reaction of hydroxy-termi nated ester oligomers with 4-ethynyl benzoyl chloride exhibited higher Tgs and better solvent resistance than comparable unendcapped polymers (50). Biphenylene end-caps have been placed on imide (40, 51), quinoline (52, 53) and quinoxaline (53) oligomers. High temperatures (> 316°C"J are required to cure... 

Harris and Hsu modified the structure of the rigid-rod poly(pyro-mellitimides) so they would display solubility in common organic solvents [59]. The approach involved the synthesis of 3,6-diphenylpyromellitic dianhydride and its polymerization with various pendent 4,4 -biphenylene diamines. The polymers, represented by structure XIV, were prepared in refluxing m-cresol... 

Iodonium tetrafluoroborate, biphenylene-X-ray structures, 1, 566 Iodopropenylation alkyl halides, 1, 469 Ionenes uses, 1, 289 Ion exchange resins pyridine polymers and, 1, 308-309 Ionization potentials pyridines, 2, 135 cts- 3-Ionol synthesis, 3, 666 cis-/3-Ionone... 

Jo, B. W. and Lenz, R. W. Liquid crystalline polymers, 7, thermotropic polyesters with main chain phenyl- 1,4-phenylene, 4,4 -biphenylene, and 1,1 -binaphthyl-4,4 -ylene units. Makromol. Chem. Rapid Commun. 3, 23 (1982)... 

Substituted-PPVs and a number of PPV copolymers have been synthesized, illustrated in Scheme 46, using the Heck reaction shown above [178-180]. Of these polymers both the phenyl-substituted PPV and the biphenylene vinylenes are soluble in organic solvents while the methyl-, trifluoromethyl-, nitro- and fluoro-substituted analogs displayed poor solubility. 

Biphenylene dimer 68, a building block for another putative carbon allotrope, was prepared [109]. However, the reaction of 68 under the conditions typical for the conversion of biphenylene to tetraphenylene failed to yield the double helical polymer or corresponding oligomer (Fig. 15.25) [107]. 

A. Rajca, A. Safronov, S. Rajca, C. R. Ross, II, J. J. Stezowski, Biphenylene Dimer. Molecular Fragment of a Two-dimensional Carbon Net and Double-stranded Polymer, J. Am. Chem. Soc. 1996, 118, 7272-7279. 

Figure 45 Synthesis of polymers with alternating binaphthylene and biphenylene units. (From Ref. 212.)...

In the presence of aromatic polymers, it reacts to form biphenylated aromatics as major products. Biphenylene end-capped polyimide oligomers were prepared using PMR technique and its curing poperties were investigated [88]. 

Economy and co-workers reported the copolyesters based on biphenylene terephthalate and HBA (5-61. These polymers exhibited excellent mechanical properties up to 250-300 C, but these copolyesters had poor processability because of their high LCTTs. 

A series of thermotropic PECs having HBA and biphenylene carbonate units were synthesized in a range of HBA moiety varying from 40 to 80 mole%. Polymer compositions were based on the ratios of starting monomers. They were checked by the yields of the polymers. 

Solubilities. Rogers et al. (16-18) have prepared and reported on a large number of aromatic polyesters and polyamides containing the 2,2 -disubstituted 4,4 -biphenylene moiety. Some of the polymers were soluble in common solvents such as tetrahydrofuran and acetone, with solubility as high as 50% in one case. The solubilities of the amide monomers synthesized in this work are shown in Table I. These compounds exhibited virtually no solubility in common solvents such as acetone but displayed fairly high solubilities in several amide solvents, with and without added salts. Lyotropic liquid crystallinity was not observed although solubilities were as high as 40% (w/w) in some solvents. 

High-spin polymers 57 and 58 consist of calix[4]arene-based macrocycles either linked or annelated via bis(3,4 -biphenylene)methyl linkers. Their design, including ferromagnetic-ferrimagnetic coupling scheme with unequal spin modules, was derived from macrocyclic macrocyclic polyradicals and annelated macrocyclic polyradicals (Fig. 38). 

In polymer 57, the S — 3 component spins of the calix[4]arene macrocycles were exchange coupled with the S — 1/2 spins of the bis(3,4/-biphenylene)methyl linkers, forming quasi-linear chain of unequal spins of S — 3 and S — 1/2. Similarly, polymer 58 consists of exchange-coupled network of unequal spins, i.e., the S — 2 component spins of the calix[4]arene macrocycles and the S — 1/2 spins of the bis(3,4 -biphenylene)methyl linkers (Fig. 38).8,113... 

I, was oxidized with lead tetraacetate (LTA), the characteristic Diels-Alder adduct with tetracyclone (TC) could be obtained even when the diene was added following completion of N2 evolution, indicating that the polymer-bound intermediate had survived for tens of seconds. Secondly, while LTA oxidation of the monomeric aminotriazole I-a, affords the corresponding biphenylenes in high yield, the only products formed by I-b, in the absence of TC, were the aryl acetates II and III (combined yield of 80%). Monomeric o-benzyne is known to dimerize at the diffusion limited rate in the gas phase, therefore, formation of the Diels-Alder product following delayed addition of diene requires a substantially slower encounter process for the polymer-bound analog. 

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