Biphenylene Polymer structure

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... 

Dimethyl-4,4 -bis(4-aminophenoxy)biphenyl has a non-coplanar disubstituted biphenylene moiety and flexible aryl units. The incorporation of the disubstituted biphenylene in a polymer chain will not change the rod-like structure of the polymer backbone but reduces the interchain interactions. The tendency to crystallize and the transition temperatures are lowered and the solubility is enhanced. ... 

The organotin-containing moiety may also be somewhat removed from the polymer chain as in the case of poly(tributyltin-4 -vinyl-biphenylcarboxylate) (Structure 17.3) where biphenylene spacers have been introduced [78,79]. 

Nematic polyurethanes derived from 4,4 -dihydroxybiphenyl and 4,4 -bipiperidine, ethylene-4,4 -bipiperidine, or trimethylene-4,4 -bipiperidine have been reported [254]. 4,4 -Bipiperidine, l,2-bis(4-piperidinyl)ethane, and l,3-bis(4-piperidinyl)pro-pane were condensed with the dichloroformates of p-phenylene, 2-methyl-l,4-phenylene, or 2,5-biphenylylene. Furthermore, two copolyurethanes were prepared either by mixing 4,4 -bipiperidine and l,2-bis(4-piperidinyl)ethane or by mixing the dichloroformates of p-phenylene and 2,5-biphenylene. The polyurethanes derived from hydroquinone or methylhydroquinone were semicrystalline polymers with a short-term thermostability up to 310 °C. The polyurethanes derived from phenyl-hydroquinone were amorphous with a thermostability up to 360 °C. The homo-and co-polyurethanes containing 4,4 -biphenylylene units formed a smectic layer structure in the solid state and a nematic melt above the melting point [254]. 

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