THIN DIBLOCK COPOLYMER FILMS ON CHEMICALLY HETEROGENEOUS SURFACES

We have used scanning force microscopy and transmission electron micro scopy to study the microphase separation of P(S-b-2VP) block copolymer s on chemically structured substrates. Gold was patterned by microcont act printing to form regions of self-assembled alkyl monolayers termin ated by -CH3 Or -OH. The differences in surface and interfacial energi es between the coexisting phases and the boundary surfaces strongly in fluence the resulting domain structure. We find that excess material a ccumulates only on layers formed above the H3C-terminated SAM. For thi s to happen, single block copolymer molecules diffuse over distances o f several micrometers. TEM investigations reveal that the block copoly mer is well ordered into lamellae parallel to the substrate over the H O-terminated SAM but that the block copolymer layers on the H3C-termin ated SAM are frequently oriented perpendicular to the substrate. This perpendicular orientation could decrease the edge free energy of the i slands that form on this layer.