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Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS: Different Behavior of Parallel and Perpendicular Lamellae.

Zhang J, Posselt D, Smilgies DM, Perlich J, Kyriakos K, Jaksch S, Papadakis CM - Macromolecules (2014)

Bottom Line: During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly.The first two regimes of swelling are associated with a significant structural rearrangement of the lamellae; i.e., the lamellae first become thicker, and then perpendicular and randomly oriented lamellae vanish, which results in a purely parallel orientation at the end of the swelling process.During drying, the deswelling is nonaffine which may be a consequence of the increase of nonfavorable segmental interactions as the solvent is removed.

View Article: PubMed Central - PubMed

Affiliation: Physik-Department, Fachgebiet Physik weicher Materie, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.

ABSTRACT
The reorientation of lamellae and the dependence of the lamellar spacing, D lam, on polymer volume fraction, ϕP, D lam ∝ ϕP (-β), in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scattering (GISAXS). A thin film of lamellae-forming poly(styrene-b-butadiene) prepared by spin-coating features lamellae of different orientations with the lamellar spacing depending on orientation. During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly. Quantitatively, the swelling process is composed of three regimes and the drying process of two regimes. The first two regimes of swelling are associated with a significant structural rearrangement of the lamellae; i.e., the lamellae first become thicker, and then perpendicular and randomly oriented lamellae vanish, which results in a purely parallel orientation at the end of the swelling process. The rearrangement is attributed to the increase of mobility of the polymer chains imparted by the solvent and to a decrease of total free energy of the thin film. In the third regime of swelling, the scaling exponent is found to be β = -0.32. During drying, the deswelling is nonaffine which may be a consequence of the increase of nonfavorable segmental interactions as the solvent is removed.

No MeSH data available.


Related in: MedlinePlus

(a) Reduced film thickness (black line) andreduced lamellar spacings(parallel lamellae: black open circles; perpendicular lamellae: redsolid circles) during solvent vapor annealing. The horizontal dashedline indicates the value of one. (b) FWHMs of the DBSs along qz (parallel lamellae, blackopen circles) and the DBSs along qy (perpendicular lamellae, red solid circles). The verticaldashed line marks the beginning of the drying process.
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fig4: (a) Reduced film thickness (black line) andreduced lamellar spacings(parallel lamellae: black open circles; perpendicular lamellae: redsolid circles) during solvent vapor annealing. The horizontal dashedline indicates the value of one. (b) FWHMs of the DBSs along qz (parallel lamellae, blackopen circles) and the DBSs along qy (perpendicular lamellae, red solid circles). The verticaldashed line marks the beginning of the drying process.

Mentions: To quantitatively analyze the data, qz profiles and qy profiles were created following the previously described procedure,from the experimental 2D GISAXS images. The lamellar spacings wereobtained using the model described in the ExperimentalSection for the parallel lamellae and Bragg’s law forthe perpendicular lamellae, respectively. Figure 4a shows the reduced lamellar spacings (normalized to the bulkvalue of Dlambulk = 220 Å) and the reduced film thickness(normalized to the value of the as-prepared film, 3260 Å) asa function of time during SVA. For the as-prepared thin film, it isclearly seen that the perpendicular lamellae (red solid circles inFigure 4a) have the same spacing as the bulksample, namely Dlamperp = 1.02Dlambulk, whereas the spacing ofthe parallel lamellae (black open circles in Figure 4a), is only Dlampar = 0.65Dlambulk, i.e., muchlower than Dlambulk.


Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS: Different Behavior of Parallel and Perpendicular Lamellae.

Zhang J, Posselt D, Smilgies DM, Perlich J, Kyriakos K, Jaksch S, Papadakis CM - Macromolecules (2014)

(a) Reduced film thickness (black line) andreduced lamellar spacings(parallel lamellae: black open circles; perpendicular lamellae: redsolid circles) during solvent vapor annealing. The horizontal dashedline indicates the value of one. (b) FWHMs of the DBSs along qz (parallel lamellae, blackopen circles) and the DBSs along qy (perpendicular lamellae, red solid circles). The verticaldashed line marks the beginning of the drying process.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4150605&req=5

fig4: (a) Reduced film thickness (black line) andreduced lamellar spacings(parallel lamellae: black open circles; perpendicular lamellae: redsolid circles) during solvent vapor annealing. The horizontal dashedline indicates the value of one. (b) FWHMs of the DBSs along qz (parallel lamellae, blackopen circles) and the DBSs along qy (perpendicular lamellae, red solid circles). The verticaldashed line marks the beginning of the drying process.
Mentions: To quantitatively analyze the data, qz profiles and qy profiles were created following the previously described procedure,from the experimental 2D GISAXS images. The lamellar spacings wereobtained using the model described in the ExperimentalSection for the parallel lamellae and Bragg’s law forthe perpendicular lamellae, respectively. Figure 4a shows the reduced lamellar spacings (normalized to the bulkvalue of Dlambulk = 220 Å) and the reduced film thickness(normalized to the value of the as-prepared film, 3260 Å) asa function of time during SVA. For the as-prepared thin film, it isclearly seen that the perpendicular lamellae (red solid circles inFigure 4a) have the same spacing as the bulksample, namely Dlamperp = 1.02Dlambulk, whereas the spacing ofthe parallel lamellae (black open circles in Figure 4a), is only Dlampar = 0.65Dlambulk, i.e., muchlower than Dlambulk.

Bottom Line: During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly.The first two regimes of swelling are associated with a significant structural rearrangement of the lamellae; i.e., the lamellae first become thicker, and then perpendicular and randomly oriented lamellae vanish, which results in a purely parallel orientation at the end of the swelling process.During drying, the deswelling is nonaffine which may be a consequence of the increase of nonfavorable segmental interactions as the solvent is removed.

View Article: PubMed Central - PubMed

Affiliation: Physik-Department, Fachgebiet Physik weicher Materie, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.

ABSTRACT
The reorientation of lamellae and the dependence of the lamellar spacing, D lam, on polymer volume fraction, ϕP, D lam ∝ ϕP (-β), in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scattering (GISAXS). A thin film of lamellae-forming poly(styrene-b-butadiene) prepared by spin-coating features lamellae of different orientations with the lamellar spacing depending on orientation. During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly. Quantitatively, the swelling process is composed of three regimes and the drying process of two regimes. The first two regimes of swelling are associated with a significant structural rearrangement of the lamellae; i.e., the lamellae first become thicker, and then perpendicular and randomly oriented lamellae vanish, which results in a purely parallel orientation at the end of the swelling process. The rearrangement is attributed to the increase of mobility of the polymer chains imparted by the solvent and to a decrease of total free energy of the thin film. In the third regime of swelling, the scaling exponent is found to be β = -0.32. During drying, the deswelling is nonaffine which may be a consequence of the increase of nonfavorable segmental interactions as the solvent is removed.

No MeSH data available.


Related in: MedlinePlus