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  • 1
    Electronic Resource
    Electronic Resource
    Crystal and molecular structures of tert-butyltetrakis(dimethylamido)tantalum(V), bromo(p-tolyl)tris(dimethylamido)tantalum(V), and [(trimethylsilyl)methyl]tetrakis(N,N-dimethylcarbamato)tantalum(V). Evidence for stabilization of .sigma.-alkyl ligands by strongly .pi.-donating ligands in early transition metal chemistry (1982)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 104 (1982), S. 4879-4884 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00382a022
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  • 2
    Electronic Resource
    Electronic Resource
    Chloro(dimethylamido) compounds of tantalum(V): Preparations, properties, and structures of [Ta(NMe2)3Cl2]2, TaCl3(NMe2)2(HNMe2), Ta(NMe2)3Cl2(HNMe2), and [TaCl2(NMe2)2(HNMe2)]2O (1981)
    s.l. : American Chemical Society
    Inorganic chemistry 20 (1981), S. 1859-1866 
    Details
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ic50220a049
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  • 3
    Electronic Resource
    Electronic Resource
    Benzocyclobutene in polymer synthesis. I. Homopolymerization of bisbenzocyclobutene aromatic imides to form high-temperature resistant thermosetting resins (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 1819-1834 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new bisbenzocyclobutene-terminated aromatic imide monomers has been synthesized from the condensation reaction of 4-aminobenzocyclobutene and the perspective dianhydride in refluxing acetic acid/toluene. The differential scanning calorimetric studies of the foregoing monomers indicated that polymerization exotherms began at 229-250°C and reached their maxima at 258-263°C. The cured samples (250-254°C; N2; 8 h) were surprisingly stable toward thermo-oxidative degradation; only 7-10% weight loss was observed after 200 h (in air) at 314°C (600°F). At higher temperatures (650 and 700°F), the most rigid structure was the most thermo-oxidatively stable. An approach to enhance both the final glass-transition temperature (Tg cure) and the thermo-oxidative stability of the bisbenzocyclobutene system was to dilute the cure-site density since the cure-site structure is the weakest part of the polymeric structure. Therefore, a series of bisbenzocyclobutene-terminated aromatic imide oligomers were prepared, using various aromatic amines as the chain-extending agents. Meta-phenylenediamine was apparently the most effective in the advancement of both the Tg (cure) and thermo-oxidative stability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260712
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  • 4
    Electronic Resource
    Electronic Resource
    Benzocyclobutene in polymer synthesis. III. Heat-resistant thermosets based on Diels-Alder polymerization of a bisbenzocyclobutene and a bismaleimideFor Parts I and II, see Refs. 1 and 2. (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 3103-3117 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several compatible mixtures of 2,2-bis[4-(N-4-benzocyclobutenyl) phthalimid-4-phenyl]hexafluoropropane (BCB) and 1,1′-(methylene di-4,1-phenylene)bismaleimide (BMI) were prepared according to the molar ratios (BCB : BMI): 1 : 1; 1 : 1.5; 1 : 3; 1.5 : 1. Complete compatibility of the mixtures was evidenced by a single initial Tg. All mixtures showed relatively low initial Tg's (61-70°C) and characteristic polymerization exotherms of benzocyclobutene-based systems (onset: 221-225°C; maximum: 257-259°C), providing an excellent processing window (ca. 155°C). The cured sample of the mixtures, pure BCB and BMI (250°C; N2; 8 h) were subjected to comparative isothermal gravimetric analysis (ITGA). After 200 h at 650°F (343°C) in circulating air, the cured BMI sample retained only 3% of its original weight, whereas the mixtures of BCB and BMI exhibited thermo-oxidative stabilities similar to BCB (13-15% weight loss). A model compound was synthesized from the intimate mixture of N-phenylmaleimide and N-benzocyclobutenyl phthalimide in 63% yield. The ITGA results and isolation of the model Diels-Alder adduct render strong support to the conviction that Diels-Alder polymerization is indeed the predominant curing process in the BCB/BMI system.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080261118
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  • 5
    Electronic Resource
    Electronic Resource
    New aromatic benzazole polymers. I. Benzobisthiazole and benzobisoxazole polymers with main-chain triarylamino units (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 1909-1924 
    Details
    ISSN: 0887-624X
    Keywords: poly(benzobisthiazole) ; poly(benzobisoxazole) ; triphenylamine derivatives ; conducting polymers ; iodine doping ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermally stable, nonrigid-rod poly(benzobisthiazoles), (R)TPA-PBZT, where R = H, Me, NMe2, and OH, and poly(benzobisoxazoles), (R)TPA-PBO, where R = Me, NMe2 containing electron-rich triarylamine groups with various para-substituents (Rs) on the pendent phenyl ring, were synthesized from either 2,5-diamino-1,4-benzenedithiol dihydrochloride or 2,4-diamino-1,5-benzenediol dihydrochloride and the respective triarylamine-based dinitrile or diacid monomer in polyphosphoric acid. Whereas (R)TPA-PBZT polymers were obtained in moderate molecular weights, analogous (R)TPA-PBO polymers were only prepared in low molecular weights. No lyotropic behaviors, characteristic of the unmodified rigid-rod benzazole polymers, as evidenced by the absence of either stir opalescence or birefringence under crosspolarizers, were observed for these homopolymers at about 10 wt % polymer concentration. Among these polymers, only (Me)TPA-PBZT and (NMe2)TPA-PBZT formed cast films with good mechanical integrity. In their pristine state, their film conductivity values were in the range of 10-10-10-9 S/cm at room temperature. Upon exposure to iodine vapor, their conductivities were increased to the maximal values of 5.0 × 10-5 S/cm ((Me)TPA-PBZT) and 4.1 × 10-4 S/cm ((NMe2)TPA-PBZT). © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1909-1924, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis and thermal properties of thermosetting bis-benzocyclobutene-terminated arylene ether monomers (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 2637-2651 
    Details
    ISSN: 0887-624X
    Keywords: benzocyclobutene ; cesium fluoride ; 4-hydroxybenzocyclobutene ; 4-trimethylsiloxybenzocyclobutene ; thermosets ; arylene ether monomers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of new bis-benzocyclobutene-endcapped arylene ether monomers was prepared and characterized. Whereas 2,6-bis(4-benzocyclobutenyloxy)benzonitrile (BCB-EBN) could be prepared in good yield using the standard procedure (K2CO3/NMP/toluene/Dean-Stark trap/120°C), other bis(benzocyclobutene) (BCB)-terminated monomers containing ether-benzophenone (BCB-EK), ether-phenylsulfone (BCB-ES), and ether-6F-benzoxazole (BCB-EBO) moieties were invariably contaminated by mono-endcapped products under similar reaction conditions. This can be attributed to a much greater activating effect of the nitrile group on the ortho-fluorides in the aromatic nucleophilic displacement reaction than the carbonyl, sulfonyl, and benzoxazolyl groups. However, the latter monomers could be synthesized (70-80%) from 4-trimethylsiloxybenzocyclobutene and respective aromatic fluorides in the presence of CsF at 140°C. Similar curing behaviors under N2 (DSC: extrapolated onset and peak temperatures at 227-230° and 260-262°C, respectively) characterized all four monomers. BCB-EK, BCB-ES, and BCB-EBN showed melting transitions at 108, 119, and 146°C, in that order. As BCB-EBO contained more rigid benzoxazole segments, it only exhibited a glass transition (Tg) at 85°C prior to curing exotherm, after it had been previously heated to 125°C. The following Tgs were observed for the cured materials: BCB-EK (201°C), BCB-EBN (224°C), BCB-ES (264°C), and BCB-EBO (282°C). The relative thermal stability according to TGA (He) results is: BCB-ES 〈 BCB-EBN 〈 BCB-EK 〈 BCB-EBO. Finally, the results from thermal analysis, infrared spectroscopic, and variable temperature microscopic studies indicated that the nitrile group plays an important role in the cure chemistry, thermal, and microstructural properties of BCB-EBN. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. A Polym. Chem. 36: 2637-2651, 1998
    Additional Material: 8 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Benzocyclobutene in polymer synthesis. II. Solid state diels-alder polymerization utilizing an in situ generated diene and an alkyne (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 3159-3172 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A novel class of aromatic imide AB-monomers with benzocyclobutene and an alkyne (primarily phenylethynyl group) as the reactive units have been prepared. The monomers have been utilized in thermally induced Diels-Alder polymerizations. The differential scanning calorimetric study of the AB-monomers provided two observations: (i) primary acetylene began its homopolymerization (202°C max.) before the electrocyclic ring opening of benzocyclobutene (270°C max.); (ii) the phenoxy group connecting between phenylacetylenyl group and the aromatic imide fragment suppressed polymerization in Diels-Alder fashion. Furthermore, thermoxidative stability evaluation on the cured samples (250°C for 8 h and then 350°C for another 8 h under N2 atmosphere), carried out at 650°F (air) for 200 h, indicated the more rigid phenylethynyl phthalimide system was the most heat-resistant.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080251118
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  • 8
    Electronic Resource
    Electronic Resource
    Aromatic polyamides containing keto-benzocyclobutene pendants (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 3539-3549 
    Details
    ISSN: 0887-624X
    Keywords: benzocyclobutene ; polyamides ; crosslinking ; rigid-rod molecular composites ; poly(p-phenylenebenzobisthiazole) ; 3,5-diaminophenyl-4-benzocyclobutenyl ketone ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of novel benzocyclobutene (BCB)-pendanted polyamides (inherent viscosities: 0.20-0.69 dL/g) was synthesized from 3,5-diaminophenyl-4-benzocyclobutenyl ketone, and terephthaloyl, isophthaloyl, 4,4′-oxydibenzoyl chlorides, as well as 4,4′-(o-phenylenedioxy)dibenzoyl chloride. The DSC studies demonstrated that the BCB crosslinking exothermic transition occurred at nearly the same temperature (max. ∼ 275°C) for all the four polyamides, and they were thermally stable up to 380°C in helium, where the weight loss started to occur. TGA and DSC studies in air indicated that the polymers, in contrast to the model compound, showed evidence of oxidation just prior to or occurring simultaneously with the BCB crosslinking reaction. This could be attributed to the oxidation of the reactive diene generated from the ring-opening of the BCB competing with the process of two BCB pendant units approaching each other for crosslinking reaction. Preliminary examination of the BCB-pendanted polyamide regenerated from a methanesulfonic acid solution indicates that the BCB ring is quite stable (DSC evidence) in the strong acid medium. © 1996 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New aromatic benzazole polymers II: Synthesis and conductivity of benzobisthiazole-co-polymers incorporated with 4-N,N-dimethylaminotriphenylamine groups (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 36 (1998), S. 713-724 
    Details
    ISSN: 0887-624X
    Keywords: poly(benzobisthiazole) ; copolymers ; 4-N,N-dimethylaminotriphenylamine ; conducting polymers ; iodine doping ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: New aromatic benzobisthiazole copolymers containing 10-70 mol % of 4-N,N-dimethylamino-triphenylamine functionality were prepared from the respective dinitrile or dicarboxylic acid monomers, terephthalic acid, and 2,5-diamino-1,4-benzene-dithiol dihydrochloride in polyphosphoric acid. At the first approximation, the copolymers containing 10 mol % or less of the triarylamino moieties in the polymer chains still preserve the capability to form anisotropic (nematic) solutions at 10 wt % polymer concentration. This is an important requirement for processing the copolymers into fibers and films with good to excellent mechanical properties. Films with good mechanical integrity were cast from the dilute methanesulfonic acid solutions of the copolymers under reduced pressure. They showed electrical conductivity values of the order of 10-11-10-10 S/cm in pristine state, with four to seven orders of magnitude increase upon exposure to mild oxidizing agents such as iodine vapor. On the contrary, the parent polymer, poly(p-phenylene benzobisthiazole) is an insulator with conductivity of less than 10-12 S/cm, and its conductivity does not improve at all with exposure to iodine vapor. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 713-724, 1998
    Additional Material: 6 Ill.
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  • 10
    facet.materialart.
    Unknown
    Highly efficient and two-photon excited stimulated Rayleigh-Bragg scattering in organic solutions (2015)
    American Institute of Physics
    Details
    Publication Date: 2015-07-21
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics
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