Near-UV and blue-light-emitting polymers were synthesized with luminescent functional groups in the side chains or in the polymer main chain. The unsubstituted fluorophores, 2,5-diphenylfuran, 2-phenylbenzoxazole, and triphenylamine, do not form excimers in solution; however, in the case of polymers, excimer emission was negligible only with 2-phenylbenzoxazole derivatives. The monomers as well as the polymers, poly(2-(4-vinylphenyl)-benzoxazole), poly{N-(4-benzoxazol-2-yl-phenyl)-NЈ-[2-(methacryloyloxy)ethyl]urea}, and the polyurea of 2-(4-aminophenyl)-5-aminobenzoxazole with 1,5-diisocyanato-2-methylpentane, were strong blue emitters; photoluminescence shifted to longer wavelengths than that of 2-phenylbenzoxazole. Lightemitting polymers containing 2,5-diphenylfuran derivatives, including poly

Poly(diethyl trimethylene-1,1-dicarboxylate) oligomers with an average degree of polymerization (DP) of 20 and a polydispersity of 1.13 have been isothermally crystallized at 30 °C from benzene and also crystallized from the melt (T m ) 176 °C). The crystals were investigated using electron microscopy (imaging and diffraction), X-ray diffraction, and computational modeling. The diffraction signals index on an orthorhombic unit cell with parameters a ) 1.554 ( 0.002 nm, b ) 1.136 ( 0.002 nm, and c (chain axis) ) 0.585 ( 0.002 nm. A space group of P212121 is assigned on the basis of systematic absences of h00, 0k0, and 00l for odd h, k, and l respectively; thus, two antiparallel chain segments pass through the basal ab plane of the unit cell. The calculated density of 1.20 g‚cm -3 is commensurate with the measured value of 1.17 ( 0.03 g‚cm -3 . The repetitive -CH2-CH2-CX2-backbone conformation, where the side groups X are ethyl esters (-COOC2H5), has the torsional angle sequence GTG h GTG h with the trans bonds at the dimethylene C-CH2-CH2-C sites. This conformation generates a 2-fold helix with a pitch that matches the measured crystallographic c-value of 0.585 nm. Ellipsoidal-shaped, lamellar-like crystals, with lateral dimensions on the micron scale but only 7.23 nm thick, are obtained by isothermal crystallization from benzene at 30 °C. Electron and X-ray diffraction data show that the molecular axes are orthogonal to the lamellar surface and that the crystal thickness matches a DP of 20. Thus, a degree of selective crystallization of molecular length occurs in these solution-grown crystals at fixed temperature. Under appropriate conditions, the crystals also stack to generate a one-dimensional lattice. This feature does not occur in the melt-crystallized fibers; in this case, the lamellar-like character is suppressed as the polydisperse molecules interpenetrate to form a crystal with a greater coherence length in the c-direction but, of course, with chain-end defects.

Abstract:Amorphous polyarylene ether homo-and copolymers were synthesized which were based upon bisphenol A and either 4,4'-dichlorodiphenylsulfone, 4,4'-difluorobenzophenone or 4,4'-difluorodiphenyl phenylphosphine oxide. Solution blends were prepared from these homo-and copolymers with linear bisphenol A based polyhydroxyether, which was used as a model for the epoxy or vinyl ester thermosetting matrix resins for composite materials. It was observed that transparent, single Tg blends could be prepared from the phosphine oxide containing homopolymer and a 50/50 phosphine oxide/dichlorodiphenylsulfone copolymer. The other homopolymers produced materials with two Tg's, implying that they were definitely phase separated systems. Thermogravimetric analysis was also conducted and the phosphine oxide blends produced high char yields suggesting utilization in fire-resistant applications. The miscibility of the phosphine oxide material has been attributed to specific hydrogen bonding interactions observed between the phosphine oxide bond and the secondary hydroxyl group in the polyhydroxy ether. This hydroxyl functionality is also present in the epoxy and vinylester precursors and it is suggested that these materials could be utilized as interface sizings for carbon fibers, which would produce a graded microstructure between the fiber and the polymer matrix systems.

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