Origin of High Segmental Mobility at Chain Ends of Polystyrene
Autor: | Shigetaka Shimada, Osamu Urakawa, Yohei Miwa, Shogo Nobukawa |
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Rok vydání: | 2010 |
Předmět: |
Polymers and Plastics
Organic Chemistry Analytical chemistry Concentration effect Site-directed spin labeling Toluene law.invention Inorganic Chemistry chemistry.chemical_compound End-group chemistry Chain (algebraic topology) law Polymer chemistry Materials Chemistry Polystyrene Solvent effects Electron paramagnetic resonance |
Zdroj: | Macromolecules. 43:7192-7199 |
ISSN: | 1520-5835 0024-9297 |
DOI: | 10.1021/ma1013644 |
Popis: | Effects of solvents on segmental dynamics of polystyrene (PS) at the chain end have been studied by the site-specific spin-label method of electron spin resonance (ESR). PS’s having similar number-average molecular weight (ca. 25 kDa) but labeled with a nitroxde at the chain end (E-PS) or midchain segments (M-PS) individually were used for the measurements. Toluene and dioctyl phthalate (DOP) which are good and theta solvents, respectively, for PS were selected as solvents. The temperature variation of ESR spectra was simulated based on the “macroscopic order with microscopic disorder” model to determine the segmental mobility of the labeled segment. The E-PS showed obviously and slightly higher mobility compared to the M-PS in the bulk PS and in the concentrated PS/DOP (50/50) solution, respectively. On the other hand, the E-PS showed the same mobility with the M-PS within experimental uncertainties in the dilute PS/toluene (1/99), concentrated PS/toluene (60/40), and dilute PS/DOP (3/97) solutions. Name... |
Databáze: | OpenAIRE |
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