Phase Behavior in Thin Films of Cylinder-Forming Block Copolymers

Knoll, Armin; Horvat, A.; Lyakhova, K. S.; Krausch, Georg; Sevink, G. J. A.; Zvelindovsky, Andrei; Magerle, R.

doi:10.1103/physrevlett.89.035501

Cited by 500 publications

(700 citation statements)

References 35 publications

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“…36 Dimensionality is another crucial factor for categorizing the confinement systems for microphase-separated structures. Onedimensional (1D) confinement is a thin film in which the substrate surface can be chemically modified to induce wetting of one of the phase-separated domains inside the film, 37,38 which is known as chemical asymmetry. The film thickness can also act as the confinement.…”

Section: Morphologies Of Bcp Under Confinementmentioning

confidence: 99%

Three-Dimensional Visualization and Characterization of Polymeric Self-Assemblies by Transmission Electron Microtomography

et al. 2017

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* S Supporting Information CONSPECTUS: Self-assembling structures and their dynamical processes in polymeric systems have been investigated using three-dimensional transmission electron microscopy (3D-TEM). Block copolymers (BCPs) self-assemble into nanoscale periodic structures called microphase-separated structures, a deep understanding of which is important for creating nanomaterials with superior physical properties, such as high-performance membranes with well-defined pore size and high-density data storage media. Because microphase-separated structures have become increasingly complicated with advances in precision polymerization, characterizing these complex morphologies is becoming increasingly difficult. Thus, microscopes capable of obtaining 3D images are required. In this article, we demonstrate that 3D-TEM is an essential tool for studying BCP nanostructures, especially those self-assembled during dynamical processes and under confined conditions. The first example is a dynamical process called order−order transitions (OOTs). Upon changing temperature or pressure or applying an external field, such as a shear flow or electric field, BCP nanostructures transform from one type of structure to another. The OOTs are examined by freezing the specimens in the middle of the OOT and then observing the boundary structures between the preexisting and newly formed nanostructures in three-dimensions. In an OOT between the bicontinuous double gyroid and hexagonally packed cylindrical structures, two different types of epitaxial phase transition paths are found. Interestingly, the paths depend on the direction of the OOT. The second example is BCP self-assemblies under confinement that have been examined by 3D-TEM. A variety of intriguing and very complicated 3D morphologies can be formed even from the BCPs that self-assemble into simple nanostructures, such as lamellar and cylindrical structures in the bulk (in free space). Although 3D-TEM is becoming more frequently used for detailed morphological investigations, it is generally used to study static nanostructures. Although OOTs are dynamical processes, the actual experiment is done in the static state, through a detailed morphological study of a snapshot taken during the OOT. Developing time-dependent nanoscale 3D imaging has become a hot topic. Here, the two main problems preventing the development of in situ electron tomography for polymer materials are addressed. First, the staining protocol often used to enhance contrast for electrons is replaced by a new contrast enhancement based on chemical differences between polymers. In this case, no staining is necessary. Second, a new 3D reconstruction algorithm allows us to obtain a high-contrast, quantitative 3D image from fewer projections than is required for the conventional algorithm to achieve similar contrast, reducing the number of projections and thus the electron beam dose. Combining these two new developments is expected to open new doors to 3D in situ real-time structural observation of polymer materials.

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Section: Morphologies Of Bcp Under Confinementmentioning

confidence: 99%

Three-Dimensional Visualization and Characterization of Polymeric Self-Assemblies by Transmission Electron Microtomography

et al. 2017

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“…[1][2][3] On the other hand, in thin film, as additional parameters such as the film thickness and interfacial tension can play a significant role, it becomes more complicated to understand its morphology. [4][5][6] In † To whom correspondence should be addressed. E-mail: dlee@dankook.ac.kr Polymer(Korea), Vol.…”

Section: Introductionmentioning

confidence: 99%

“…36, No. 4,2012 particular, such BCP nanostructures can provide many possible applications such as nanolithography, 6-8 ultra high-density data storage media, 9-11 nanostructured templates, 12,13 and photonic crystals 14 when they are prepared in thin films. In general, to take BCP morphology in thermodynamic equilibrium for the feasible applications mentioned above, the thin film is thermally annealed above the glass transition temperature (T g ) of both blocks, so that its ordering quality is improved and defect levels become reduced.…”

Section: Introductionmentioning

confidence: 99%

Morphological Transitions of Symmetric Polystyrene-block-Poly(1,4-butadiene) Copolymers in Thin Films upon Solvent-Annealing

이동은¹,

김응건²,

이동현³

2012

Polymer Korea

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Morphological characteristics and formation of symmetric polystyrene-block-poly(1,4-butadiene) copolymer (PS-b-PBD) in thin films upon solvent-annealing were investigated by using atomic force microscopy (AFM). The thin films solvent-annealed in cyclohexane revealed the perforated lamellae of poly(1,4-butadiene) in the matrix of polystyrene while those solvent-annealed in n-hexane exhibited highly disordered patterns. Interestingly, when the thin films of PS-b-PBD were solvent-annealed with binary mixtures of cyclohexane and n-hexane, the morphological transition from the perforated lameallae to the perpendicularly-oriented lamellae of poly(1,4-butadiene) could be induced by changing the mixing ratio of both solvents. We also demonstrated that after microdomians of poly(1,4-butadiene) were successfully degraded by UV-O 3 , linear poly(dimethyl siloxane) chains were back-filled into the etched regions of the thin film and then converted to silica nano-objects by oxygen plasma treatments.

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“…5,18,19 Some studies have also shown that the orientation of microphase-separated structures can be controlled by exposing block copolymer films to solvent vapor and drying at a controlled evaporation rate. 13,18,[20][21][22][23][24][25][26][27] We have reported the experimental visualization of a threedimensional (3D) helical morphology for a polystyrene-block-polybutadiene-block-poly(methyl methacrylate) triblock terpolymer (SBM) using transmission electron microtomography (TEMT). 28 The TEMT observations revealed that the double-helical structure was composed of polybutadiene (PB) helical microdomains around hexagonal-packed polystyrene (PS) cylinder cores in a poly(methyl methacrylate) (PMMA) matrix, even though the block copolymer was not chiral.…”

Section: Introductionmentioning

confidence: 99%

“…Many techniques have been used to orient the cylindrical structures perpendicular to the substrate in the copolymer film, including surface affinity, 3-6 the application of shear force, 7 electric fields, [8][9][10][11] and magnetic fields. [12][13][14][15][16] In addition, surface roughness is critical for a vertical orientation. 17 However, few of these techniques can maintain the perpendicular orientation in the copolymer thick film over several micrometers.…”

Section: Introductionmentioning

confidence: 99%

Highly oriented and ordered double-helical morphology in ABC triblock terpolymer films up to micrometer thickness by solvent evaporation

Hong

Higuchi

Sugimori

et al. 2012

Polym J

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A triblock terpolymer, polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM), formed a double-helical nanoscale structure, composed of polybutadiene (PB) helical microdomains around hexagonally packed polystyrene (PS) cores in a poly(methyl methacrylate) matrix. The orientation of double-helical morphologies at various film thicknesses were studied using transmission electron microtomography, following solvent annealing and drying at a controlled solvent evaporation rate. The evaporation rate of the solvent and the film thickness were important factors in whether the double-helical microdomains were oriented parallel or perpendicular with respect to the substrate. In some cases, the perpendicularly aligned double-helical morphology extended several micrometers from the substrate to the air surface. A similar experiment using polystyrene-blockpoly(methyl methacrylate) diblock copolymer proved that the presence of helical PB microdomains around PS cylinders is the key factor in achieving a uniform orientation over several micrometers throughout the film thickness.

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Phase Behavior in Thin Films of Cylinder-Forming Block Copolymers

Cited by 500 publications

References 35 publications

Three-Dimensional Visualization and Characterization of Polymeric Self-Assemblies by Transmission Electron Microtomography

Three-Dimensional Visualization and Characterization of Polymeric Self-Assemblies by Transmission Electron Microtomography

Morphological Transitions of Symmetric Polystyrene-block-Poly(1,4-butadiene) Copolymers in Thin Films upon Solvent-Annealing

Highly oriented and ordered double-helical morphology in ABC triblock terpolymer films up to micrometer thickness by solvent evaporation

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