Micro X-ray diffraction mapping of a fluorene copolymer fibre
Journal article, 2013

Using raster-scanning wide-angle X-ray scattering, we investigate oriented fibres of the low bandgap conjugated polymer, poly[2,7-(9,9-dioctylfluorene)-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (F8TBT), that was developed in particular for polymer solar cells. For the first time, structural data are provided for F8TBT. Our results demonstrate that the nano-scale structure of this polymer is closely related to the externally observable features of the fibre, and thus emphasise the importance of having full control over the local molecular conformation. Liquid-crystalline phases are observed at elevated temperatures, and the molecular alignment in the drawn fibres yields scattering patterns that are dominated by broad peaks of equatorial diffuse scattering. The significant degree of preferred orientation facilitates the analysis, leading to estimates of (average) nearest-neighbour packing distances and coherence length of this macromolecule. In particular, we observe a pronounced broad signal assigned to packing of the conjugated backbone with an approximate spacing of 4.00–4.39 Å that is coherent over 5-6 polymer segments.

Conjugated polymer fibre

Liquid-crystalline polymer

Synchrotron X-ray diffraction

Author

Christian Müller

Chalmers, Chemical and Biological Engineering, Polymer Technology

Morteza Esmaeli

Norwegian University of Science and Technology (NTNU)

Christian Riekel

European Synchrotron Radiation Facility (ESRF)

Dag W. Breiby

Norwegian University of Science and Technology (NTNU)

Olle Inganäs

Linköping University

Polymer

0032-3861 (ISSN)

Vol. 54 2 805-811

Subject Categories

Polymer Chemistry

DOI

10.1016/j.polymer.2012.10.059

More information

Latest update

4/20/2018