title: Interfacial free energy driven nanophase separation in poly(3-hexylthiophene)/[6,6]-phenyl-C61-butyric acid methyl ester thin films.
abstract: The nanostructure of thermally annealed thin films of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blends on hydrophobic and hydrophilic substrates was studied to unravel the relationship between the substrate properties and the phase structure of polymer blends in confined geometry. Indeed, the nature of the employed substrates was found to affect the extent of phase separation, the PCBM aggregation state and the texture of the whole system. In particular, annealing below the melting temperature of the polymer yielded the formation of PCBM nanometric crystallites on the hydrophobic substrates, while mostly amorphous microscopic aggregates were formed on the hydrophilic ones. Moreover, while an enhanced in-plane orientation of P3HT lamellae was promoted on hydrophobic substrates, a markedly tilted geometry was produced on the hydrophilic ones. The observed effects were interpreted in terms of a simple model connecting the interface free energy for the blend films to the different polymer chain mobility and diffusion velocity of PCBM molecules on the different substrates.
authors.affiliation: Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemistry, University of Catania and CSGI, Catania, Italy.
authors.forename: Giovanni Li
authors.initials: GL
authors.lastname: Destri
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Keller
authors.forename: Marinella
authors.initials: M
authors.lastname: Catellani
authors.forename: Francesco
authors.initials: F
authors.lastname: Punzo
authors.forename: Klaus D
authors.initials: KD
authors.lastname: Jandt
authors.forename: Giovanni
authors.initials: G
authors.lastname: Marletta
mesh_terms: D020148:Butyric Acid / Q000737:chemistry*; D004952:Esters; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures; D014961:X-Ray Diffraction
chemical_list: D004952:Esters; D020148:Butyric Acid