Glass Transition Temperature of Conjugated Polymers by Oscillatory Shear Rheometry
Artikel i vetenskaplig tidskrift, 2017

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.

Författare

[Person 8c380a58-0508-4cd0-8f22-598e36d6075f not found]

Pennsylvania State University

[Person bc1a7f24-2006-4e5e-962d-04c492742757 not found]

Pennsylvania State University

[Person 5f5eb31b-4197-4cdd-83f1-5acddc7533ad not found]

Pennsylvania State University

[Person afd422f7-86b1-4e59-ba9e-c94c746cb797 not found]

Pennsylvania State University

[Person aab67efa-f956-419c-ada1-45bcb6f2b9ad not found]

Chalmers, Kemi och kemiteknik, Tillämpad kemi, Polymerteknologi

[Person 996508a6-aef9-4b8a-854c-c1b98d3f9192 not found]

Pennsylvania State University

[Person a684362e-3a07-454c-abdb-229bd0e651c5 not found]

Pennsylvania State University

Macromolecules

00249297 (ISSN) 15205835 (eISSN)

Vol. 50 13 5146-5154

Ämneskategorier

Polymerkemi

DOI

10.1021/acs.macromol.7b00712

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Senast uppdaterat

2018-04-06