Phase Transition and Phase Transformation in Block Copolymer Nanoparticles

Higuchi, Takeshi; Motoyoshi, Kiwamu; Sugimori, Hidekazu; Jinnai, Hiroshi; Yabu, Hiroshi; Shimomura, Masatsugu

doi:10.1002/marc.201000299

Cited by 90 publications

(120 citation statements)

References 32 publications

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“…32 The unidirectionally stacked lamellae and onion-like structures are types of 'isomers' based on the lamellar structure of the nanoparticles. As we reported previously, [20][21][22][23][24][25]33 these two structures can be controlled by changing the solution concentration and by thermal annealing. Moreover, the periodicity of the phase separation can be controlled by changing the molecular weights of block copolymers within particles.…”

Section: Hierarchical Assembly Of Cds Nanoparticles H Yabu Et Almentioning

confidence: 85%

Hierarchical assembly of CdS nanoparticles in polymer particles with phase separation structures

Yabu

Endo

Koike

et al. 2011

Polym J

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The preparation of size-controlled CdS nanoparticles in block copolymer micelles and formation of composite particles of CdS nanoparticles and polymers are described in this paper. Uniformly sized CdS nanoparticles with different emission wavelengths were successfully synthesized. In addition, composite Janus particles, unidirectionally stacked lamellae particles and onion particles were formed by combining CdS nanoparticles and polymer blend or block copolymer systems. This approach provides a simple route for the preparation of functional organic/inorganic composite particles.

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Section: Hierarchical Assembly Of Cds Nanoparticles H Yabu Et Almentioning

confidence: 85%

Hierarchical assembly of CdS nanoparticles in polymer particles with phase separation structures

Yabu

Endo

Koike

et al. 2011

Polym J

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“…55 The morphological transformation between an axially stacked lamellar and onionlike structure was observed under spherical 3D confinement. 54 Figure 6 shows the morphological transformation of lamellaforming SI BCP in nanoparticles dispersed in water (i.e., a poor solvent for SI) by applying thermal annealing. In the annular dark field (ADF)-STEM images, the dark and bright regions are unstained PS and PI phases stained with OsO 4 , respectively.…”

Section: Accounts Of Chemical Researchmentioning

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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“…Specifically, microstructures with multiple spherical layers, that is, spherically concentric lamellae or onion-like structures, have been predicted in lamella-forming diblock copolymer nanoparticles by Monte Carlo (MC) simulations 21,22 and by dynamic density functional theory simulations, 23 and have been observed in the experiments with various methods. [24][25][26][27][28][29] These studies demonstrate that the spherical boundaries of nanoparticles, especially those with preferential surfaces, can strongly influence the microstructures of diblock nanoparticles by distorting the flat lamellae into spherical ones. Moreover, the perpendicular lamellae, that is, the stacked lamellae, have been observed for diblock copolymer nanoparticles in experiments 25,26,29,30 and simulations, 22 in which the lamellae maintain the same flat characteristics as the bulk structures (perpendicular to one of symmetric axe).…”

Section: Introductionmentioning

confidence: 84%

“…[24][25][26][27][28][29] These studies demonstrate that the spherical boundaries of nanoparticles, especially those with preferential surfaces, can strongly influence the microstructures of diblock nanoparticles by distorting the flat lamellae into spherical ones. Moreover, the perpendicular lamellae, that is, the stacked lamellae, have been observed for diblock copolymer nanoparticles in experiments 25,26,29,30 and simulations, 22 in which the lamellae maintain the same flat characteristics as the bulk structures (perpendicular to one of symmetric axe). In addition to spherical and perpendicular lamellae, a series of non-lamellar microstructures, including the embedded structure and Janus-type, tennis ball-, mushroom-and screw-like structures, have also been observed in symmetric diblock copolymer nanoparticles.…”

Section: Introductionmentioning

confidence: 84%

“…Generally speaking, the microstructures of diblock copolymer nanoparticles are strongly dependent on the polymer parameters, that is, the block ratios and the degrees of incompatibility. 23,29 We are aware that the polymer parameters near the phase-diagram boundaries are of special interest because they are able to deform into a series of microstructures for the diblock copolymers under confinement. 13 Hence, an extensive study that examines the surface-field effects of the microstructures of cylinder-forming diblock copolymer nanoparticles, especially those with special polymer parameters, is desirable.…”

Section: Introductionmentioning

confidence: 99%

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Surface-field-induced microstructures of asymmetric diblock copolymer nanoparticles

Liu

et al. 2011

Polym J

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The microstructures of asymmetric diblock copolymer nanoparticles were investigated using real-space self-consistent field theory. The nanoparticle boundary provides a spherical confinement in which the highly deformable copolymers are forced into a closed and crowded space. The surface-field-induced effects on the microstructures were examined systematically, and a rich variety of novel structures, such as mixtures of distorted cylinders and spherical lamellae, was observed in the copolymer nanoparticles. Investigations of the free energies indicate that the surface-field-induced structural transitions are of the first order. The formation mechanism of the confinement-induced structures was reasonably elucidated, based on the interactions between the polymer chains and confinement boundaries, and on the spherical symmetry from confinements. Our theoretical results are in good agreement with available simulation and experimental observations.

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Phase Transition and Phase Transformation in Block Copolymer Nanoparticles

Cited by 90 publications

References 32 publications

Hierarchical assembly of CdS nanoparticles in polymer particles with phase separation structures

Hierarchical assembly of CdS nanoparticles in polymer particles with phase separation structures

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

Surface-field-induced microstructures of asymmetric diblock copolymer nanoparticles

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