Comparison of the Vibrational Spectra and Assignments for <i>α</i>-Syndiotactic, <i>β</i>-Syndiotactic, Isotactic, and Atactic Polystyrene and Toluene

Nyquist, Richard A.; Putzig, C. L.; Leugers, M. A.; McLachlan, R.D.; Thill, Bruce P.

doi:10.1366/0003702924124321

Cited by 54 publications

(59 citation statements)

References 8 publications

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“…[37] www.interscience.wiley.com/journal/jrs [29 -32] and C-C-C [29,32] 543 Under Si In-plane ring-to-vinyl bending/rocking @ 575 (6%)…”

Section: Dft Calculationsmentioning

confidence: 99%

“…In-plane ring-to-chain bending/rocking [31] [26] 1196 13 @ 1242 (4%) 13 A 1 α xx α yy α zz [15,30,31] 1249 Degradation product [26] 1326 14 @ 1367 (3%) 14 B 2 α yz [30,32] 1368 Graphite [15,28] [30 -32] and maybe δCH 2 [15,30,32] 1583 1567 13 8b @ 1618 (2%) Ordinary Raman: 8b B 2 α yz [15,30,31] SERS: 8b and graphite [15,28] 1600 1594 7.8 8a @ 1644 (3%) Ordinary Raman: 8a A 1 α xx α yy α zz [15,30,31] SERS: 8a and graphite [15,28] Ordinary Raman and SERS spectra, obtained experimentally for polystyrene, are compared in columns 1-3. Vibrational modes and their ordinary Raman band positions, calculated for the styrene monomer using DFT, are listed in column 4.…”

Section: Dft Calculationsmentioning

confidence: 99%

“…Band assignments, with symmetry information, are given in column 5. References [28][29][30][31][32][33] give ordinary Raman data only. References [15,26] give both ordinary Raman and SERS data.…”

Section: Dft Calculationsmentioning

confidence: 99%

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Surface‐enhanced Raman scattering from polystyrene on gold clusters

Anema

Brolo

Felten

et al. 2010

J Raman Spectroscopy

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Surface-enhanced Raman scattering (SERS) constitutes a spectroscopic method of rapidly growing importance, and polystyrene is a widely used compound of great industrial importance. In this work, SERS data were obtained from polystyrene samples prepared by vapor deposition of gold and plasma-induced polymerization of styrene gas. A thorough examination of this data is presented. The relationships between sample preparation parameters, gold-cluster morphology, and SERS intensity were elucidated. Using Wilson's notation, vibrations were assigned to all bands between 250 and 1750 cm −1 in the ordinary Raman and SERS spectra of polystyrene. The correct assignment of these bands would be a significant achievement because they have been controversial in the literature for ∼30 years. Our assignments were made by reviewing the literature and comparing the assignments found there to spectral data acquired during this study; they were confirmed using density functional theory (DFT) calculations performed on the styrene monomer. The orientation of polystyrene's phenyl ring, relative to the gold surface, was determined. It has been suggested that reactions involving silver catalyze polystyrene degradation during SERS, but we found that silver is not necessary for the degradation to occur.

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“…[37] www.interscience.wiley.com/journal/jrs [29 -32] and C-C-C [29,32] 543 Under Si In-plane ring-to-vinyl bending/rocking @ 575 (6%)…”

Section: Dft Calculationsmentioning

confidence: 99%

Section: Dft Calculationsmentioning

confidence: 99%

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Surface‐enhanced Raman scattering from polystyrene on gold clusters

Anema

Brolo

Felten

et al. 2010

J Raman Spectroscopy

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“…The absorbance signals of pxylene (485 cm -1 ) and m-xylene (432 cm -1 ) were normalized to the absorbance of an internal standard signal of sPS at 1180 cm -1 in order to correct for the thickness of the membrane. [12] The quantitative estimation of complexed solvent in sPS was obtained by thermogravimetric analysis using a Seiko TG/DTA220 in the range 30-300 8C at a heating rate of 5 8C N min -1 under the purge of N 2 gas.…”

Section: Introductionmentioning

confidence: 99%

Study on δ-Form Complex in a Syndiotactic Polystyrene/Organic Molecules System, 1. Preferential Complexing Behavior of Xylene Isomers

Sivakumar¹,

Yamamoto²,

Amutharani³

et al. 2002

Macromol. Rapid Commun.

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“…O sistema PrBrCp* 2 THF/ MAO, na ausência de solvente, apresentou conversão comparável a estes dados, porém em período de tempo muito mais curto (1,5 h). , 540 (deformação do anel fora do plano) que são características de poliestireno amorfo 21 . Os espectros de RMN de 13 C dos polímeros indicaram a presença de multipleto na região do C1 (145-146 ppm), característico de poliestireno atático 22 , o que implica na ausência de estereoespecificidade dos sistemas catalíticos empregados.…”

Section: Polimerização De Estirenounclassified

Polimerização de estireno utilizando compostos organolantanídeos ativados por MAO

Maia¹,

Quini²,

Miotti³

et al. 2006

Quím. Nova

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Recebido em 22/6/05; aceito em 30/3/06; publicado na web em 25/7/06 STYRENE POLYMERIZATION USING ORGANOLANTHANIDE COMPOUNDS ACTIVATED BY MAO. In an attempt to improve the performance of organolanthanide catalysts we investigated the use of the industrially important cocatalyst methylaluminoxane (MAO) to activate organolanthanide compounds in olefin polymerization. The catalytic systems LnBrCp 2 (THF) 2 / MAO (Cp=cyclopentadienyl) and LnBrCp* 2 THF/MAO (Cp*= pentamethylcyclopentadienyl), Ln=Pr and Yb, were active in styrene polymerization but inactive in ethylene and propylene polymerization. These systems produced atactic polystyrene with conversions of up to 8.2% (PrBrCp* 2 THF, Al/Ln=200, T=80 o C, t=4 h) in toluene. In the absence of solvent, the conversion is 26.0% (1.5 h) and the molar mass of the atactic polystyrene is almost ten times higher (43 kg/mol).Keywords: organolanthanide compounds; homogeneous catalysis; olefin polymerization. INTRODUÇÃOA singular química dos lantanídeos tem sido muito utilizada na aplicação de seus derivados organometálicos como reagentes e catalisadores em síntese orgânica, principalmente em razão da combinação de carga elevada e raios iônicos grandes. Devido à habilidade que esses compostos possuem em catalisar a formação de ligações C-C, têm sido muito estudados em reações de polimerização de olefinas, entre outras 1 . Compostos organometálicos de lantanídeos têm sido estudados há 25 anos como catalisadores na polimerização de etileno e de α-olefinas. Este interesse se deve à alta atividade apresentada por alguns compostos organolantanídeos frente à polimerização de etileno e à capacidade de conduzir a polimerização de modo vivo, além de polimerizarem monômeros polares, dienos, estireno e derivados Tendo em vista o avanço dos estudos no campo da polimerização de olefinas com organolantanídeos, propôs-se o estudo uso de compostos organolantanídeos LnBrCp 2 (THF) 2 e LnBrCp* 2 THF, Ln = Pr e Yb, Cp = ciclopentadienil, Cp* = pentametilciclopentadienil, associados ao MAO na polimerização de estireno e de outras olefinas (etileno e propilleno). Foram abordados os efeitos dos diferentes tipos de catalisadores, contendo íons lantanídeos do começo e do final da série, do tipo de olefina e de algumas condições de reação, como temperatura e relação molar Al/Ln, na atividade catalítica. PARTE EXPERIMENTALTodas as manipulações foram realizadas sob atmosfera de argônio pré-purificado. THF e tolueno foram refluxados na presença de Na/benzofenona, desoxigenados e imediatamente usados. Os óxidos de praseodímio e itérbio (99,99%), NaCp (2,0 mol/L em THF) e NaCp* (0,5 mol/L em THF) foram adquiridos da Aldrich, etileno e propileno, da Petroquímica União e MAO (10% em Al, em tolueno), da Akzo Nobel. Estireno (Casa Americana) foi tratado com CaCl 2 anidro, seguido de CaH 2 e destilação à pressão reduzida. A %Ln dos catalisadores foi determinada por titulação com EDTA 9 e a %Br, por titulação com AgNO 3 . As curvas termogravimétricas TG/DTG dos compostos organolantanídeos foram registradas na term...

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Comparison of the Vibrational Spectra and Assignments for α-Syndiotactic, β-Syndiotactic, Isotactic, and Atactic Polystyrene and Toluene

Cited by 54 publications

References 8 publications

Surface‐enhanced Raman scattering from polystyrene on gold clusters

Surface‐enhanced Raman scattering from polystyrene on gold clusters

Study on δ-Form Complex in a Syndiotactic Polystyrene/Organic Molecules System, 1. Preferential Complexing Behavior of Xylene Isomers

Polimerização de estireno utilizando compostos organolantanídeos ativados por MAO

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