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Philippe Michaud - One of the best experts on this subject based on the ideXlab platform.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic anhydride and benzoic acid in n methyl 2 pyrrolidone 3 absolute number average molecular weights and glass transition temperatures
Macromolecular Chemistry and Physics, 1997Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Jacque Dubois, Philippe MichaudAbstract:In depth study of low molecular weight poly(imide-amide)s (PIA) obtained by copolycondensation of 4,4'-methylenedi(Phenyl Isocyanate), trimellitic anhydride and benzoic acid by 1 H and 13 C NMR spectroscopy and size-exclusion chromatography allows the determination of their absolute number-average molecular weights M n,abs . Viscosimetric measurements reveal that, dissolved in N-methyl-2-pyrrolidone, these low molecular weight PIAs should be semi-rigid because of the presence of very short crystalline chains. By using the semi-empirical Fox-Flory relation, the extrapolated glass transition temperature equals 300 °C for high molecular weight.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic anhydride and benzoic acid in n methyl 2 pyrrolidone 2 structural defects observed by 1h and 13c nmr
Macromolecular Chemistry and Physics, 1996Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Philippe MichaudAbstract:The in depth examination (by 1 H and 13 C NMR, DSC, SEC and TGA) of the low-molecular-weight poly(imide-amide)s synthesized with the mixture [4,4'-methylenedi(Phenyl Isocyanate) (M) + trimellitic acid anhydride (T) + benzoic acid (B)] in N-methyl-2-pyrrolidone (NMP) at temperatures lower than 180°C allowed the identification and quantitative determinations of all the unexpected and relatively stable structures. While amide functions are readily synthesized, the formation of imide from anhydride and Isocyanate functions passes through 4-amido-1,2-benzenedicarboxylic acid (T i ), 1,4-di-amido-2-benzenecarboxylic acid (T) and disubstituted urea (u). At 180 °C T i completely disappears but traces of T and u remain ; thus, the formation of imide can never reach its theoretical quantity. Traces of moisture in NMP may play the role of catalyst in the formation of imide, and reaction mechanisms are proposed.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic acid anhydride and benzoic acid in n methyl 2 pyrrolidone 1 the microstructure studied by 1h and 13c nmr
Macromolecular Chemistry and Physics, 1993Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Philippe MichaudAbstract:Low-molecular-weight poly(imide-amide)s (PIA) obtained by polycondensation at 180°C of 4,4'-methylenedi(Phenyl Isocyanate), trimellitic acid anhydride and benzoic acid were studied by 1 H and 13 C NMR. Complementary 1 H and 13 C information was used to determine the distribution of II, IA, AA sequences and to show that the repartition of imide (I) and amide (A) groups along the chains is random. According to the composition of the monomer mixture, a slight deficiency of I is reproducibly observed. Non-reacted benzoic acid is found, and unexpected traces of urea and amic acid groups are present in the PIA chains
Nathalie Sinteszydowicz - One of the best experts on this subject based on the ideXlab platform.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic anhydride and benzoic acid in n methyl 2 pyrrolidone 3 absolute number average molecular weights and glass transition temperatures
Macromolecular Chemistry and Physics, 1997Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Jacque Dubois, Philippe MichaudAbstract:In depth study of low molecular weight poly(imide-amide)s (PIA) obtained by copolycondensation of 4,4'-methylenedi(Phenyl Isocyanate), trimellitic anhydride and benzoic acid by 1 H and 13 C NMR spectroscopy and size-exclusion chromatography allows the determination of their absolute number-average molecular weights M n,abs . Viscosimetric measurements reveal that, dissolved in N-methyl-2-pyrrolidone, these low molecular weight PIAs should be semi-rigid because of the presence of very short crystalline chains. By using the semi-empirical Fox-Flory relation, the extrapolated glass transition temperature equals 300 °C for high molecular weight.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic anhydride and benzoic acid in n methyl 2 pyrrolidone 2 structural defects observed by 1h and 13c nmr
Macromolecular Chemistry and Physics, 1996Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Philippe MichaudAbstract:The in depth examination (by 1 H and 13 C NMR, DSC, SEC and TGA) of the low-molecular-weight poly(imide-amide)s synthesized with the mixture [4,4'-methylenedi(Phenyl Isocyanate) (M) + trimellitic acid anhydride (T) + benzoic acid (B)] in N-methyl-2-pyrrolidone (NMP) at temperatures lower than 180°C allowed the identification and quantitative determinations of all the unexpected and relatively stable structures. While amide functions are readily synthesized, the formation of imide from anhydride and Isocyanate functions passes through 4-amido-1,2-benzenedicarboxylic acid (T i ), 1,4-di-amido-2-benzenecarboxylic acid (T) and disubstituted urea (u). At 180 °C T i completely disappears but traces of T and u remain ; thus, the formation of imide can never reach its theoretical quantity. Traces of moisture in NMP may play the role of catalyst in the formation of imide, and reaction mechanisms are proposed.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic acid anhydride and benzoic acid in n methyl 2 pyrrolidone 1 the microstructure studied by 1h and 13c nmr
Macromolecular Chemistry and Physics, 1993Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Philippe MichaudAbstract:Low-molecular-weight poly(imide-amide)s (PIA) obtained by polycondensation at 180°C of 4,4'-methylenedi(Phenyl Isocyanate), trimellitic acid anhydride and benzoic acid were studied by 1 H and 13 C NMR. Complementary 1 H and 13 C information was used to determine the distribution of II, IA, AA sequences and to show that the repartition of imide (I) and amide (A) groups along the chains is random. According to the composition of the monomer mixture, a slight deficiency of I is reproducibly observed. Non-reacted benzoic acid is found, and unexpected traces of urea and amic acid groups are present in the PIA chains
Stacey F. Bent - One of the best experts on this subject based on the ideXlab platform.
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formation of stable nitrene surface species by the reaction of adsorbed Phenyl Isocyanate at the ge 100 2 1 surface
Langmuir, 2013Co-Authors: Keith T. Wong, Jukka T Tanskanen, Stacey F. BentAbstract:The reaction of Phenyl Isocyanate (PIC) following adsorption at the Ge(100)-2 × 1 surface has been investigated both experimentally and theoretically by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, quantum chemical calculations, and molecular dynamics simulations. PIC initially adsorbs by [2 + 2] cycloaddition across the C═N bond of the Isocyanate, as previously reported, but this initial product converts to a second product on the time scale of minutes at room temperature. The experimental and theoretical results show that the second product formed is Phenylnitrene (C6H5N) covalently bonded to the germanium surface via a single Ge–N bond. This conclusion is further supported by FTIR spectroscopy experiments and density functional theory calculations using Phenyl Isocyanate-15N and Phenyl-d5 Isocyanate.
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reaction of Phenyl Isocyanate and Phenyl isothiocyanate with the ge 100 2 1 surface
Journal of Physical Chemistry C, 2010Co-Authors: Paul W Loscutoff, Keith T. Wong, Stacey F. BentAbstract:The adsorption of Phenyl Isocyanate and Phenyl isothiocyanate at the Ge(100)-2 × 1 surface was probed using multiple internal reflection Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT), and X-ray photoelectron spectroscopy (XPS). Results for Phenyl Isocyanate indicate that the saturation product is a [2 + 2] cycloaddition reaction product across the C═N bond, forming a surface-bound carbonyl. DFT reveals that this is the most stable of the expected products, and its calculated vibrational spectrum agrees closely with experimental spectra. FTIR spectroscopy studies of Phenyl isothiocyanate reveal multiple surface adducts, with the product of the [2 + 2] cycloaddition reaction across the C═S bond as the major species and the product of the [2 + 2] cycloaddition reaction across the C═N bond as a minor product. In addition to these products, an excess of sulfur measured by XPS indicates the presence of a dissociative desorption product. The DFT calculated pathways and vibration...
Quang Tho Pham - One of the best experts on this subject based on the ideXlab platform.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic anhydride and benzoic acid in n methyl 2 pyrrolidone 3 absolute number average molecular weights and glass transition temperatures
Macromolecular Chemistry and Physics, 1997Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Jacque Dubois, Philippe MichaudAbstract:In depth study of low molecular weight poly(imide-amide)s (PIA) obtained by copolycondensation of 4,4'-methylenedi(Phenyl Isocyanate), trimellitic anhydride and benzoic acid by 1 H and 13 C NMR spectroscopy and size-exclusion chromatography allows the determination of their absolute number-average molecular weights M n,abs . Viscosimetric measurements reveal that, dissolved in N-methyl-2-pyrrolidone, these low molecular weight PIAs should be semi-rigid because of the presence of very short crystalline chains. By using the semi-empirical Fox-Flory relation, the extrapolated glass transition temperature equals 300 °C for high molecular weight.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic anhydride and benzoic acid in n methyl 2 pyrrolidone 2 structural defects observed by 1h and 13c nmr
Macromolecular Chemistry and Physics, 1996Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Philippe MichaudAbstract:The in depth examination (by 1 H and 13 C NMR, DSC, SEC and TGA) of the low-molecular-weight poly(imide-amide)s synthesized with the mixture [4,4'-methylenedi(Phenyl Isocyanate) (M) + trimellitic acid anhydride (T) + benzoic acid (B)] in N-methyl-2-pyrrolidone (NMP) at temperatures lower than 180°C allowed the identification and quantitative determinations of all the unexpected and relatively stable structures. While amide functions are readily synthesized, the formation of imide from anhydride and Isocyanate functions passes through 4-amido-1,2-benzenedicarboxylic acid (T i ), 1,4-di-amido-2-benzenecarboxylic acid (T) and disubstituted urea (u). At 180 °C T i completely disappears but traces of T and u remain ; thus, the formation of imide can never reach its theoretical quantity. Traces of moisture in NMP may play the role of catalyst in the formation of imide, and reaction mechanisms are proposed.
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low molecular weight poly imide amide s obtained by copolycondensation of 4 4 methylenedi Phenyl Isocyanate trimellitic acid anhydride and benzoic acid in n methyl 2 pyrrolidone 1 the microstructure studied by 1h and 13c nmr
Macromolecular Chemistry and Physics, 1993Co-Authors: Nathalie Sinteszydowicz, Quang Tho Pham, Philippe MichaudAbstract:Low-molecular-weight poly(imide-amide)s (PIA) obtained by polycondensation at 180°C of 4,4'-methylenedi(Phenyl Isocyanate), trimellitic acid anhydride and benzoic acid were studied by 1 H and 13 C NMR. Complementary 1 H and 13 C information was used to determine the distribution of II, IA, AA sequences and to show that the repartition of imide (I) and amide (A) groups along the chains is random. According to the composition of the monomer mixture, a slight deficiency of I is reproducibly observed. Non-reacted benzoic acid is found, and unexpected traces of urea and amic acid groups are present in the PIA chains
Keith T. Wong - One of the best experts on this subject based on the ideXlab platform.
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formation of stable nitrene surface species by the reaction of adsorbed Phenyl Isocyanate at the ge 100 2 1 surface
Langmuir, 2013Co-Authors: Keith T. Wong, Jukka T Tanskanen, Stacey F. BentAbstract:The reaction of Phenyl Isocyanate (PIC) following adsorption at the Ge(100)-2 × 1 surface has been investigated both experimentally and theoretically by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed desorption, quantum chemical calculations, and molecular dynamics simulations. PIC initially adsorbs by [2 + 2] cycloaddition across the C═N bond of the Isocyanate, as previously reported, but this initial product converts to a second product on the time scale of minutes at room temperature. The experimental and theoretical results show that the second product formed is Phenylnitrene (C6H5N) covalently bonded to the germanium surface via a single Ge–N bond. This conclusion is further supported by FTIR spectroscopy experiments and density functional theory calculations using Phenyl Isocyanate-15N and Phenyl-d5 Isocyanate.
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reaction of Phenyl Isocyanate and Phenyl isothiocyanate with the ge 100 2 1 surface
Journal of Physical Chemistry C, 2010Co-Authors: Paul W Loscutoff, Keith T. Wong, Stacey F. BentAbstract:The adsorption of Phenyl Isocyanate and Phenyl isothiocyanate at the Ge(100)-2 × 1 surface was probed using multiple internal reflection Fourier transform infrared (FTIR) spectroscopy, density functional theory (DFT), and X-ray photoelectron spectroscopy (XPS). Results for Phenyl Isocyanate indicate that the saturation product is a [2 + 2] cycloaddition reaction product across the C═N bond, forming a surface-bound carbonyl. DFT reveals that this is the most stable of the expected products, and its calculated vibrational spectrum agrees closely with experimental spectra. FTIR spectroscopy studies of Phenyl isothiocyanate reveal multiple surface adducts, with the product of the [2 + 2] cycloaddition reaction across the C═S bond as the major species and the product of the [2 + 2] cycloaddition reaction across the C═N bond as a minor product. In addition to these products, an excess of sulfur measured by XPS indicates the presence of a dissociative desorption product. The DFT calculated pathways and vibration...