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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

Selected 2D GISAXS images during drying. The times after the beginningof the SVA are indicated. The exposure time is 30 s for all images.The intensity scale is given at the bottom.
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fig3: Selected 2D GISAXS images during drying. The times after the beginningof the SVA are indicated. The exposure time is 30 s for all images.The intensity scale is given at the bottom.

Mentions: We now turn to the drying process. Figure 3 shows selected 2D GISAXS images during drying. Owing to theintenseDBSs and the intense diffuse scattering in the plane of incidence,a rod-shaped beam stop had to be used to protect the detector. Onlythe first- and third-order DBSs are present, and no DDSRs appear,indicating that only the parallel lamellae persist during and afterdrying and that they are symmetric. Such behavior is to be expectedbecause (i) it costs energy and requires a large-scale mass transportto form tilted lamellae out of parallel lamellae, therefore this ishindered, and (ii) the polymers lose mobility as the solvent evaporatesgradually during drying which additionally hampers reorientation.


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)

Selected 2D GISAXS images during drying. The times after the beginningof the SVA are indicated. The exposure time is 30 s for all images.The intensity scale is given at the bottom.
© Copyright Policy
Related In: Results  -  Collection

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

fig3: Selected 2D GISAXS images during drying. The times after the beginningof the SVA are indicated. The exposure time is 30 s for all images.The intensity scale is given at the bottom.
Mentions: We now turn to the drying process. Figure 3 shows selected 2D GISAXS images during drying. Owing to theintenseDBSs and the intense diffuse scattering in the plane of incidence,a rod-shaped beam stop had to be used to protect the detector. Onlythe first- and third-order DBSs are present, and no DDSRs appear,indicating that only the parallel lamellae persist during and afterdrying and that they are symmetric. Such behavior is to be expectedbecause (i) it costs energy and requires a large-scale mass transportto form tilted lamellae out of parallel lamellae, therefore this ishindered, and (ii) the polymers lose mobility as the solvent evaporatesgradually during drying which additionally hampers reorientation.

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