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Glass Transition Te...
Glass Transition Temperature of Conjugated Polymers by Oscillatory Shear Rheometry
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- Xie, R. (author)
- Pennsylvania State University
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- Lee, Y. (author)
- Pennsylvania State University
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- Aplan, M.P. (author)
- Pennsylvania State University
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- Caggiano, N.J. (author)
- Pennsylvania State University
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- Müller, Christian, 1980 (author)
- Chalmers tekniska högskola,Chalmers University of Technology
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- Colby, R.H. (author)
- Pennsylvania State University
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- Gomez, E.D. (author)
- Pennsylvania State University
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(creator_code:org_t)
- 2017-06-27
- 2017
- English.
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In: Macromolecules. - : American Chemical Society (ACS). - 1520-5835 .- 0024-9297. ; 50:13, s. 5146-5154
- Related links:
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http://dx.doi.org/10...
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https://doi.org/10.1...
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Abstract
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- The stiff backbones of conjugated polymers can lead to a rich phase behavior that includes both crystalline and liquid crystalline phases, making measurements of the glass transition challenging. In this work, the glass transitions of regioregular poly(3-hexylthiophene-2,5-diyl) (RR P3HT), regiorandom (RRa) P3HT, and poly((9,9-bis(2-octyl)-fluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5′,5″-diyl) (PFTBT) are probed by linear viscoelastic measurements as a function of molecular weight. We find two glass transition temperatures (T g 's) for both RR and RRa P3HT and one for PFTBT. The higher T g , T α , is associated with the backbone segmental motion and depends on the molecular weight, such that the Flory-Fox model yields T α = 22 and 6 °C in the long chain limit for RR and RRa P3HT, respectively. For RR P3HT, a different molecular weight dependence of T α is seen below M n = 14 kg/mol, suggesting this is the typical molecular weight of intercrystal tie chains. The lower T g (T αPE ≈ -100 °C) is associated with the side chains and is independent of molecular weight. RRa P3HT exhibits a lower T α and higher T αPE than RR P3HT, possibly due to a different degree of nanophase separation between the side chains and the backbones. In contrast, PFTBT only exhibits one T g above -120 °C, at 144 °C in the long chain limit.
Subject headings
- NATURVETENSKAP -- Kemi -- Polymerkemi (hsv//swe)
- NATURAL SCIENCES -- Chemical Sciences -- Polymer Chemistry (hsv//eng)
Publication and Content Type
- art (subject category)
- ref (subject category)
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