Origin of High Segmental Mobility at Chain Ends of Polystyrene

Autor: Shigetaka Shimada, Osamu Urakawa, Yohei Miwa, Shogo Nobukawa
Rok vydání: 2010
Předmět:
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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