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Jaczewska, J., Budkowski, A., Bernasik, A., Moons, E., Rysz, J.,Polymer vs. Solvent Diagram of Film Structures Formed in Spin-Cast Poly(3-alkylthiophene) Blends, Macromolecules 41, 13 (2008), p. 48 ...

Two blends (1:1 and 5:3 w:w) of poly(2-vinylpyridine) (PVP) and partly brominated polystyrene were spin-cast (with constant inherent domain scale 2R = 4.2 ± 0.5 μm) onto a gold substrate which had been microcontact printed with stripes of hexadecanethiol SAM. Two chemical patterns on the substrate were used, one with symmetrical stripes (4 μm Au/4 μm hexadecane SAM) and the other with narrow gold stripes and wider SAM stripes (3 μm/5 μm). The resulting film morphologies were mapped with atomic force microscopy. Secondary ion mass spectrometry shows that raised regions on the film surface correspond to PVP-rich domains, and the surface polymer composition extends all the way down to the substrate. Fourier analysis reveals structural modes (λ/n) smaller than the pattern periodicity λ = 8 μm. PVP preferentially adsorbs to the gold regions of the pattern. For the asymmetric pattern, which has a relatively small Au area interacting with the PVP, the fundamental mode (n = 1) is extinguished and higher-order sub...

Blends of poly(2-vinylpyridine), polystyrene, and poly(methyl methacrylate) of four different compositions (2:3:0, 3:2:0, 1:1:0, and 2:2:1 w:w:w) were spin-cast onto periodically (λ = 4 μm) patterned substrate (with two alternating stripes: Au attracting PVP and neutral self-assembled monolayer), and resulting film morphologies (with inherent domain scale 0.2 λ ≤ R < 1.8 λ) were recorded with scanning force microscopy and examined with Fourier transform analysis and the integral geometry approach. The morphologies depend on not only spatial (R/λ) but also compositional commensuration between blends and symmetric pattern: λ/2-substructures are present, in addition to λ-structures, for isolated (2:3:0) but not for continuous (3:2:0) PVP domains. This explains also the data for 1:1:0 blends which present a transition from isolated to continuous PVP domains (for larger R values). In turn, interfacial compatibilizer (PMMA in 2:2:1) results in the well-ordered λ/2-substructures for both morphology types.

Sectional views of thin films of symmetric polystyrene/polyisoprene (PS/PI) blends spin- cast from toluene (C6H5CH3) onto CH3- and COOH-terminated self-assembled monolayers (CH3-SAM and COOH-SAM) show concave- (sharp-edged) and convex-shaped (round) protrusions, respectively, while other morphology features are identical. A 3-dimensional phase domain arrangement was determined with spectroscopic techniques (profiling and mapping mode of dynamic secondary ion mass spectrometry, dSIMS, and X-ray photoelectron spectroscopy). Surface topography was examined with atomic force microscopy and monitored, during the dSIMS analysis, with secondary electrons. In addition, solvent evaporation from PS, PI, and PS/PI layers cast on CH3-SAM and COOH-SAM was determined. The collected data were used to put forward a model of morphology formation and to elucidate the role of evaporation speed dependent on substrate chemistry in this process, demonstrated here for the first time.

Topography and composition images of model thin films of deuterated polystyrene (dPS) and polyisoprene with different blend compositions were analyzed with an extension of integral-geometry approach. Surface patterns, formed in the course of spin-casting from toluene onto self-assembled monolayers (SAM), were recorded with scanning force microscopy. Their relation with lateral phase domain structures was demonstrated by dynamic secondary ion mass spectrometry, yielding maps of dPS distribution. Morphological measures, which cannot be provided by Fourier transform analysis (FTA), characterize individual images, compositional series of the surface patterns and individual features of the patterns. Different morphologies (nucleation- and spinodal-type and hole- and island-dominated ones) are consistently characterized by the Minkowski measures and related parameters. For instance, the latter can measure circular character of the individual features and estimate dominant lateral length (determined rigorously w...