https://doi.org/10.1140/epje/i2012-12129-3
Regular Article
Competition between substrate-mediated π-π stacking and surface-mediated Tg depression in ultrathin conjugated polymer films
1
Department of Physics and Astronomy, University of Sheffield, S3 7RH, Sheffield, UK
2
Department of Chemical and Biological Engineering, University of Sheffield, S1 3JD, Sheffield, UK
3
Diamond Light Source Ltd, Diamond House, Harwell Science and Innovation Campus, OX11 0DE, Oxfordshire, UK
4
Department of Chemistry, University of Sheffield, S3 7HF, Sheffield, UK
* e-mail: t.wang@hotmail.com
Received:
4
July
2012
Revised:
5
October
2012
Accepted:
22
November
2012
Published online:
14
December
2012
We report surface and interface effects in dynamics and chain conformation in the thin film of conjugated polymer PCDTBT. To probe dynamic anomalies, we measure the glass transition temperature (Tg) of PCDTBT films as a function of thickness, and find that there is a significant depression in Tg for films less than 100nm thick; a result qualitatively similar to that observed in many other polymer film systems. However, for films less than 40nm, the Tg converges to a constant value of 20K below its bulk value. Grazing incidence X-ray diffraction shows depth-dependent molecular organization that is associated with the unusual thickness-dependent dynamics.
Key words: Soft Matter: Polymers and Polyelectrolytes
© EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg, 2012