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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

SAXS intensity profile of the bulk sample.The arrows mark thepositions of the first-, second-, and third-order Bragg reflections.
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fig1: SAXS intensity profile of the bulk sample.The arrows mark thepositions of the first-, second-, and third-order Bragg reflections.

Mentions: Knowledge of the structure ofthe P(S-b-B) diblockcopolymer in the bulk equilibrium state is mandatory to properly evaluatethe thin film results. Thus, the bulk structure of the P(S-b-B) diblock copolymer was determined at room temperatureby means of SAXS. Figure 1 shows the intensityprofile which features three diffraction peaks. The intensity of thesecond-order peak is quite weak, compared to the third-order peak,indicating that the lamellae are almost symmetric which is in accordancewith the fact that the copolymer is compositionally symmetric. Theratio of the q positions of the three Bragg peaksof 1:1.98:3.01 indicates the presence of a lamellar structure. UsingBragg’s law and the peak position of the first-order Braggreflection, the lamellar spacing is found at Dlambulk = 220 ±4 Å.


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)

SAXS intensity profile of the bulk sample.The arrows mark thepositions of the first-, second-, and third-order Bragg reflections.
© Copyright Policy
Related In: Results  -  Collection

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

fig1: SAXS intensity profile of the bulk sample.The arrows mark thepositions of the first-, second-, and third-order Bragg reflections.
Mentions: Knowledge of the structure ofthe P(S-b-B) diblockcopolymer in the bulk equilibrium state is mandatory to properly evaluatethe thin film results. Thus, the bulk structure of the P(S-b-B) diblock copolymer was determined at room temperatureby means of SAXS. Figure 1 shows the intensityprofile which features three diffraction peaks. The intensity of thesecond-order peak is quite weak, compared to the third-order peak,indicating that the lamellae are almost symmetric which is in accordancewith the fact that the copolymer is compositionally symmetric. Theratio of the q positions of the three Bragg peaksof 1:1.98:3.01 indicates the presence of a lamellar structure. UsingBragg’s law and the peak position of the first-order Braggreflection, the lamellar spacing is found at Dlambulk = 220 ±4 Å.

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