Micro X-ray diffraction mapping of a fluorene copolymer fibre
Artikel i vetenskaplig tidskrift, 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.

Synchrotron X-ray diffraction

Liquid-crystalline polymer

Conjugated polymer fibre


Christian Müller

Chalmers, Kemi- och bioteknik, Polymerteknologi

Morteza Esmaeli

Norges Teknisk-Naturvitenskapelige Universitet

Christian Riekel

European Synchrotron Radiation Facility

Dag W. Breiby

Norges Teknisk-Naturvitenskapelige Universitet

Olle Inganäs

Linköpings universitet


0032-3861 (ISSN)

Vol. 54 805-811