Issue 3, 2015

Bimodal crystallization at polymer–fullerene interfaces


The growth-kinetics of [6,6]-phenyl C61-butyric acid methyl ester (PCBM) crystals, on two different length-scales, is shown to be controlled by the thickness of the polymer layer within a PCBM–polymer bilayer. Using a model amorphous polymer we present evidence, from in situ optical microscopy and grazing-incidence X-ray diffraction (GIXD), that an increased growth-rate of nanoscale crystals impedes the growth of micron-sized, needle-like PCBM crystals. A combination of neutron reflectivity and GIXD measurements, also allows us to observe the establishment of a liquid–liquid equilibrium composition-profile between the PCBM layer and a polymer-rich layer, before crystallization occurs. While the interfacial composition-profile is independent of polymer-film-thickness, the growth-rate of nanoscale PCBM crystals is significantly larger for thinner polymer films. A similar thickness-dependent behavior is observed for different molecular weights of entangled polymer. We suggest that the behavior may be related to enhanced local-polymer-chain-mobility in nanocomposite thin-films.

Graphical abstract: Bimodal crystallization at polymer–fullerene interfaces

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Article information

Article type
22 Sep 2014
26 Nov 2014
First published
26 Nov 2014
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2015,17, 2216-2227

Author version available

Bimodal crystallization at polymer–fullerene interfaces

D. Môn, A. M. Higgins, D. James, M. Hampton, J. E. Macdonald, M. B. Ward, P. Gutfreund, S. Lilliu and J. Rawle, Phys. Chem. Chem. Phys., 2015, 17, 2216 DOI: 10.1039/C4CP04253K

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