Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/925461

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Title
Evolution of laterally phase-separated polyfluorene blend morphology studied by X-ray spectromicroscopy
Author/Creator
McNeill, Christopher R.;  Watts, Benjamin;  Thomsen, Lars;  Belcher, Warwick J.;  Greenham, Neil C.;  Dastoor, Paul C.;  Ade, Harald
Institution
The University of Newcastle. Faculty of Science & Information Technology, School of Mathematical and Physical Sciences
Description
The morphological evolution of laterally phase-separated polyfluorene blends composed of poly(9,9′-dioctylfluorene-co-bis-N,N′-(4-butylphenyl)-bis-N,N′-phenyl-1,4-phenylenediamine) (PFB) and poly(9,9′-dioctylfluoreneco-benzothiadiazole) (F8BT) has been studied with scanning transmission X-ray microscopy (STXM). The degree of phase separation in the films was regulated by controlling the time spent in a solvent-saturated atmosphere during solution processing, typically between 1 and 6 min. For films with a 5:1 weight ratio of PFB:F8BT, we observe a systematic increase in domain size and domain purity, with the enclosed F8BT-rich domains growing both through coalescence and flow of material across the domain boundary. For 1:1 and 1:5 blends a more complicated evolution of morphology is observed with evidence of additional vertical stratification. For 1:1 blends, primary and secondary phase separation is observed, with the evolution of the PFB-rich phase evolving similar to the 5:1 blend. Interestingly,the PFB-rich spots within the F8BT domain are observed to disappear after around 3 min of morphology evolution. Similar behavior is also seen in 1:5 blends, where a dramatic partial phase inversion is observed. The origin of this transition is attributed to subsequent vertical phase separation, with PFB wetting the substrate/film interface or film/vapor interface or both. In addition to the mechanisms of phase separation, the implications of the observed morphology changes for device performance are also discussed.
Relation
Macromolecules Vol. 42, Issue 9, p. 3347-3352
Publisher Link
http://dx.doi.org/10.1021/ma801816r
Date
2009
Publisher
American Chemical Society
Keyword(s)
phase separation;  X-ray spectromicroscopy;  polymer blends;  morphology;  X-ray microscopy
Resource Type
journal article
Identifier
http://hdl.handle.net/1959.13/925461
Identifier
ISSN:0024-9297
Reviewed
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Subject
"Macromolecules"
 
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