Phase Behavior of Pure Diblocks and Binary Diblock Blends of Poly(ethylene)−Poly(ethylethylene)

Zhao, Jin; Majumdar, B.; Schulz, Mark F.; Bates, Frank S.; Almdal, Kristoffer; Mortensen, K.; Hajduk, Damian A.; Grüner, Sol M.

doi:10.1021/ma9507251

Cited by 207 publications

(286 citation statements)

References 34 publications

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“…In contrast to the work of Zhao et al (1996) and Buzza et al (2000) we did not observe the slope in the order of 1/2 for the diblock copolymer with the lamellar morphology. A possible explanation is the missing long-range order of the lamellar morphology for the block copolymers of this study.…”

Section: Master Curvescontrasting

confidence: 99%

Morphology and elasticity of polystyrene-block-polyisoprene diblock copolymers in the melt

Haenelt

Georgopanos

Abetz

et al. 2014

Korea-Aust. Rheol. J.

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The influence of morphology on the viscoelastic properties of melts of microphase-separated polystyrene-block-polyisoprene (PS-b-PI) diblock copolymers was investigated in oscillatory and creep recovery experiments. By means of anionic polymerization, three PS-b-PI diblock copolymers with a narrow molecular weight distribution and different types of morphology (spherical, cylindrical and lamellar microstructure) were prepared. Linear viscoelastic shear oscillations and creep recovery experiments in shear were performed in order to determine the elastic and viscous properties of the diblock copolymers in the melt at small and large time scales. Our analysis reveals that melts of diblock copolymers are characterized by a pronounced elastic behavior leading to a relatively large recoverable deformation in creep recovery experiments. The elasticity of the diblock copolymers is also revealed by the appearance of the creep-ringing effect. Morphological investigations were carried out to establish relations between microstructure and melt elasticity. Since ordering phenomena take place in melts of diblock copolymers until an equilibrium morphology is achieved, the storage modulus G' of diblock copolymer melts increases with time up to a steady-state value.

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Section: Master Curvescontrasting

confidence: 99%

Morphology and elasticity of polystyrene-block-polyisoprene diblock copolymers in the melt

Haenelt

Georgopanos

Abetz

et al. 2014

Korea-Aust. Rheol. J.

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“…In addition, two-component block copolymer blends were employed in order to examine samples with weight fractions between those of the neat polymers, a technique that has been described elsewhere. 46 Blend samples were prepared by codissolving the two components in cyclohexane at approximately 80°C, followed by precipitation in methanol and drying in vacuum at 200°C. In order to observe the higher-order SAXS peaks necessary for identification of the equilibrium mesophase structure (see below), many of the samples required extended annealing, which was performed for 2-35 days in evacuated and sealed ampules at 160 -200°C.…”

Section: Methodsmentioning

confidence: 99%

Crystallization of tethered polyethylene in confined geometries

Weimann

Hajduk

Chu

et al. 1999

J. Polym. Sci. B Polym. Phys.

104

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“…Park et al reported that hexagonally perforated layers 29 are converted to {121} DG in thin films 22,30 in the OOT from hexagonally perforated lamellar (HPL) to DG structures, whereas this kind of orderly transition is not observed in shear-oriented bulk. 17 3D observations by TEM and 3D-TEM were carried out using a JEM-2200FS system (JEOL Co., Ltd., Japan) operating at 200 kV, details of which can be found elsewhere. 26 Adapted with permission from ref 13.…”

Section: D Structural Analysis Of Ootsmentioning

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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Phase Behavior of Pure Diblocks and Binary Diblock Blends of Poly(ethylene)−Poly(ethylethylene)

Cited by 207 publications

References 34 publications

Morphology and elasticity of polystyrene-block-polyisoprene diblock copolymers in the melt

Morphology and elasticity of polystyrene-block-polyisoprene diblock copolymers in the melt

Crystallization of tethered polyethylene in confined geometries

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

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