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Aromatic Poly (aromatic + poly)
Selected AbstractsPolyimide Orientation Layers Prepared from Lyotropic Aromatic Poly(Amic Ethyl Ester)s,ADVANCED FUNCTIONAL MATERIALS, Issue 5 2003C. Neuber Abstract The synthesis and characterization of liquid-crystalline precursor polymer solutions[1] for polyimides permit for the first time the preparation of bulk- and surface-oriented polyimide thin films from the nematic lyotropic state by shear. A special shearing technique was developed and optimized to orient viscous solutions into thin films with thicknesses below 100 nm. The films produced were thermally imidized and characterized by polarized light microscopy, as well as polarized FTIR and UV-vis spectroscopy before and after imidization. The dichroic ratios (DRs) before imidization were determined as 5 by FTIR, and 4.5 by UV-vis spectroscopies. After imidization the DRs increased to 14 and 7, respectively. The shear-oriented layers possess a surface profile in the form of striations, which was characterized by mechanical surface scanning and atomic force microscopy (AFM). The profile height was determined in the nanometer range in contrast to the profile distance in the micrometer range, thus the latter is a magnitude larger than the film thickness. To quantify and compare the orientation potential of the obtained orientation layers, cells with a liquid-crystalline host and a dichroic azo dye as guest were prepared. Interesting for this class of rod-like polyimides is that layers, which were cast from low concentration isotropic solutions and rubbed, exhibited an almost doubled DR of 15 compared to analogously prepared alignment layers based on commercial flexible polyimide systems (DR,=,8). [source] Synthesis and properties of novel organosoluble aromatic poly(ether ketone)s containing pendant methyl groups and sulfone linkagesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Shou-Ri Sheng Abstract Several novel aromatic poly(ether ketone)s containing pendant methyl groups and sulfone linkages with inherent viscosities of 0.62,0.65 dL/g were prepared from 2-methyldiphenylether and 3-methyldiphenylether with 4,4,-bis(4-chloroformylphenoxy)diphenylsulfone and 4,4,-bis (3-chloroformylphenoxy)diphenylsulfone by electrophilic Friedel,Crafts acylation in the presence of N,N -dimethylformamide with anhydrous AlCl3 as a catalyst in 1,2-dichloroethane. These polymers, having weight-average molecular weights in the range of 57,000,71,000, were all amorphous and showed high glass-transition temperatures ranging from 160.5 to 167°C, excellent thermal stability at temperatures over 450°C in air or nitrogen, high char yields of 52,57% in nitrogen, and good solubility in CHCl3 and polar solvents such as N,N -dimethylformamide, dimethyl sulfoxide, and N -methyl-2-pyrrolidone at room temperature. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 84.6,90.4 MPa, Young's moduli of 2.33,2.71 GPa, and elongations at break of 26.1,27.4%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Hydroxyl-terminated hyperbranched aromatic poly(ether-ester)s: Synthesis, characterization, end-group modification, and optical propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2008Thiyagarajan Shanmugam Abstract Novel AB2 -type monomers such as 3,5-bis(4-methylolphenoxy)benzoic acid (monomer 1), methyl 3,5-bis(4-methylolphenoxy) benzoate (monomer 2), and 3,5-bis(4-methylolphenoxy)benzoyl chloride (monomer 3) were synthesized. Solution polymerization and melt self-polycondensation of these monomers yielded hydroxyl-terminated hyperbranched aromatic poly(ether-ester)s. The structure of these polymers was established using FTIR and 1H NMR spectroscopy. The molecular weights (Mw) of the polymers were found to vary from 2.0 × 103 to 1.49 × 104 depending on the polymerization techniques and the experimental conditions used. Suitable model compounds that mimic exactly the dendritic, linear, and terminal units present in the hyperbranched polymer were synthesized for the calculation of degree of branching (DB) and the values ranged from 52 to 93%. The thermal stability of the polymers was evaluated by thermogravimetric analysis, which showed no virtual weight loss up to 200 °C. The inherent viscosities of the polymers in DMF ranged from 0.010 to 0.120 dL/g. End-group modification of the hyperbranched polymer was carried out with phenyl isocyanate, 4-(decyloxy)benzoic acid and methyl red dye. The end-capping groups were found to change the thermal properties of the polymers such as Tg. The optical properties of hyperbranched polymer and the dye-capped hyperbranched polymer were investigated using ultraviolet-absorption and fluorescence spectroscopy. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5414,5430, 2008 [source] Long-range effects of chirality in aromatic poly(isocyanide)sJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2006David B. Amabilino Abstract The preparation of optically active atropoisomeric polymers which present chiral backbones, thanks to induction during their synthesis from stereogenic centers, located far away from the skeleton is possible, thanks principally to semirigid conformations of the promesogenic spacers between them. The result is that chiral "information" can be passed as far as 21 Å from the asymmetric center to the carbon atom that forms the polymeric chain in poly(isocyanide)s. The sense of chiral induction in these conformationally rigid polymers parallels the helical sense of the cholesteric phases, as well as to the helical senses of chiral smectic C phases, induced by the monomers in nematic and smectic C phases, respectively. All these phenomena obey the odd,even rules proposed for chiral sense changes in these liquid crystalline phases. Noncovalent interactions play an important part in the induction process, in which steric arguments can be used to justify the inductions observed. The methodology can be used to prepare macromolecules, which display switching behavior upon thermal or electrochemical stimulus. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3161,3174, 2006 [source] Novel thermally stable poly(amine hydrazide)s and poly(amine-1,3,4-oxadiazole)s for luminescent and electrochromic materialsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2005Guey-Sheng Liou Abstract We describe the preparation, characterization, and luminescence of four novel electrochromic aromatic poly(amine hydrazide)s containing main-chain triphenylamine units with or without a para-substituted N,N -diphenylamino group on the pendent phenyl ring. These polymers were prepared from either 4,4,-dicarboxy-4,- N,N -diphenylaminotriphenylamine or 4,4,-dicarboxytriphenylamine and the respective aromatic dihydrazide monomers via a direct phosphorylation polycondensation reaction. All the poly(amine hydrazide)s were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent and flexible films with good mechanical properties. These poly(amine hydrazide)s exhibited strong ultraviolet,visible absorption bands at 346,348 nm in N -methyl-2-pyrrolidone (NMP) solutions. Their photoluminescence spectra in NMP solutions or as cast films showed maximum bands around 508,544 and 448,487 nm in the green and blue region for the two series of polymers. The hole-transporting and electrochromic properties were examined by electrochemical and spectroelectrochemical methods. All obtained poly(amine hydrazide)s and poly(amine-1,3,4-oxadiazole)s exhibited two reversible oxidation redox couples at 0.8 and 1.24 V vs. Ag/AgCl in acetonitrile solution and revealed excellent stability of electrochromic characteristics, changing color from original pale yellow to green and then to blue at electrode potentials of 0.87 and 1.24 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3245,3256, 2005 [source] Novel family of triphenylamine-containing, hole-transporting, amorphous, aromatic polyamides with stable electrochromic propertiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 10 2005Tzy-Hsiang Su Abstract We report the preparation and characterization of a series of novel electrochromic, aromatic poly(amine amide)s with pendent triphenylamine units. The synthesis proceeded via direct phosphorylation polycondensation between a novel diamine, N,N -bis(4-aminophenyl)- N,,N,-diphenyl-1,4-phenylenediamine, and various aromatic dicarboxylic acids. All the poly(amine amide)s were amorphous and readily soluble in many common organic solvents and could be solution-cast into transparent, tough, and flexible films with good mechanical properties. They exhibited good thermal stability and 10% weight-loss temperatures above 540 °C. Their glass-transition temperatures were 263,290 °C. These polymers in N -methyl-2-pyrrolidinone solutions exhibited strong ultraviolet,visible absorption peaks at 307,358 nm and photoluminescence peaks around 532,590 nm in the green region. The hole-transporting and electrochromic properties were studied with electrochemical and spectroelectrochemical methods. Cyclic voltammograms of poly(amine amide) films prepared by the casting of polymer solutions onto an indium tin oxide coated glass substrate exhibited two reversible oxidation redox couples at 0.65 and 1.03 V versus Ag/AgCl in an acetonitrile solution. All the poly(amine amide)s showed excellent stability with respect to their electrochromic characteristics; the color of the films changed from pale yellow to green and then blue at 0.85 and 1.25 V, respectively. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 2085,2098, 2005 [source] Synthesis and properties of new aromatic poly(ester-imide)s derived from 4- p -biphenyl-2,6-bis(4-trimellitimidophenyl) pyridine and various dihydroxy compoundsPOLYMER INTERNATIONAL, Issue 1 2007Hossein Behniafar Abstract A novel class of wholly aromatic poly(ester-imide)s, having a biphenylene pendant group, with inherent viscosities of 0.32,0.49 dL g,1 was prepared by the diphenylchlorophosphate-activated direct polyesterification of the preformed imide-ring-containing diacid, 4- p -biphenyl-2,6-bis(4-trimellitimidophenyl)pyridine (1) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A reference diacid, 2,6-bis(trimellitimido)pyridine (2) without a biphenylene pendant group and two phenylene rings in the backbone, was also synthesized for comparison purposes. At first, with due attention to structural similarity and to compare the characterization data, a model compound (3) was synthesized by the reaction of compound 1 with two mole equivalents of phenol. Moreover, the optimum condition of polymerization reactions was obtained via a study of the model compound synthesis. All of the resulting polymers were characterized by Fourier transform infrared and 1H NMR spectroscopy and elemental analysis. The ultraviolet ,max values of the poly(ester-imide)s were also determined. All of the resulting polymers exhibited excellent solubility in common organic solvents, such as pyridine, chloroform, tetrahydrofuran, and m -cresol, as well as in polar organic solvents, such as N -methyl-2-pyrrolidone, N,N -dimethylacetamide, N,N -dimethylformamide, and dimethyl sulfoxide. The crystalline nature of the polymers obtained was evaluated by means of wide-angle X-ray diffraction. The resulting poly(ester-imide)s showed nearly an amorphous nature, except poly(ester-imide) derived from 4,4,-dihydroxy biphenyl. The glass transition temperatures (Tg) of the polymers determined by differential scanning calorimetry thermograms were in the range 298,342 °C. The 10% weight loss temperatures (T10%) from thermogravimetric analysis curves were found to be in the range 433,471 °C in nitrogen. Films of the polymers were also prepared by casting the solutions. Copyright © 2006 Society of Chemical Industry [source] Synthesis and characterization of novel aromatic poly(amide-imide)s derived from 2,2,-bis(4-trimellitimidophenoxy)biphenyl or 2,2,-bis(4-trimellitimidophenoxy)-1,1,-binaphthyl and various aromatic diaminesPOLYMER INTERNATIONAL, Issue 7 2003Ahmad Banihashemi Abstract New aromatic diimide-dicarboxylic acids having kinked and cranked structures, 2,2,-bis(4-trimellitimidophenoxy)biphenyl (2a) and 2,2,-bis(4-trimellitimidophenoxy)-1,1,-binaphthyl (2b), were synthesized by the reaction of trimellitic anhydride with 2,2,-bis(4-aminophenoxy)biphenyl (1a) and 2,2,-bis(4-aminophenoxy)-1,1,-binaphthyl (1b), respectively. Compounds 2a and 2b were characterized by FT-IR and NMR spectroscopy and elemental analyses. Then, a series of novel aromatic poly(amide-imide)s were prepared by the phosphorylation polycondensation of the synthesized monomers with various aromatic diamines. Owing to structural similarity, and a comparison of the characterization data, a model compound was synthesized by the reaction of 2b with aniline. The resulting polymers with inherent viscosities of 0.58,0.97 dl g,1 were obtained in high yield. The polymers were fully characterized by FT-IR and NMR spectroscopy. The ultraviolet ,max values of the poly(amide-imide)s were also determined. The polymers were readily soluble in polar aprotic solvents. They exhibited excellent thermal stabilities and had 10% weight loss at temperatures above 500 °C under a nitrogen atmosphere. Copyright © 2003 Society of Chemical Industry [source] Synthesis and characterization of aromatic/cycloaliphatic poly(amide- imide-imide)s from bis(4-amino- 3,5-dimethylphenyl) cycloalkane derivativesPOLYMER INTERNATIONAL, Issue 8 2007Bhuvana Sowrirajalu Abstract A series of novel aromatic diamines containing cycloaliphatic moieties was synthesized by the reaction of cycloalkanones like cyclohexanone and cycloheptanone with 2,6-dimethylaniline. The tetrimide diacid was synthesized using the prepared diamine with 3,3,,4,4,-benzophenonetetracarboxylic acid dianhydride/pyromellitic dianhydride and p -aminobenzoic acid. The polymers were prepared by treating the tetrimide diacid with different aromatic diamines. The structures of the monomers and polymers were identified using elemental analysis and Fourier transform infrared, 1H NMR and 13C NMR spectroscopy. The polymers show excellent solubility. The polymers are amorphous and have high optical transparency. They also show good thermal stability and their Tg value is found to be in the range 268,305 °C. Copyright © 2007 Society of Chemical Industry [source] | ||||||||||