Front Cover: Macromol. Rapid Commun. 17/2006

Jinnai, Hiroshi; Hasegawa, Hirokazu; Nishikawa, Yukihiro; Sevink, G. J. A.; Braunfeld, Michael B.; Agard, David A.; Spontak, Richard J.

doi:10.1002/marc.200690032

Cited by 6 publications

(6 citation statements)

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“…At φ H ∼ 60%, both PS and PMMA domains were still partially continuous, indicative of the BµE phase. 19,75 At φ H ∼ 68%, all of the PS domains were separated and formed droplets in a matrix of PMMA. As seen in the corresponding FFT analysis (Figure 2B), spectra of both morphologies (BµE and DµE) that formed in the range of 56% < φ H < 80% had only one broad peak in the low q region, indicating that both morphologies were microemulsions.…”

Section: Resultsmentioning

confidence: 99%

Phase Behavior and Dimensional Scaling of Symmetric Block Copolymer−Homopolymer Ternary Blends in Thin Films

et al. 2009

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The phase behavior and dimensional scaling of symmetric ternary blends composed of poly(styrene-block-methyl methacrylate) block copolymers and the corresponding polystyrene and poly(methyl methacrylate) homopolymers in thin films were investigated as a function of χN (the product of the Flory−Huggins interaction parameter and the overall degree of polymerization of the block copolymer), α (the ratio of the degree of polymerization of the homopolymers to that of the block copolymer), and ϕH (the volume fraction of homopolymers in the blends). The phase transitions were characterized by three methods: disappearance of high-order peaks in the fast Fourier transform (FFT) spectra from scanning electron microscopy (SEM) images, application of the amphiphilicity factor determined from the FFTs, and, in the case of thicker films, the appearance of either microphase- or macrophase-separated domains in SEM images. Above the order−disorder transition (ODT) in the χN−ϕH phase diagram, the symmetric ternary blends transitioned from lamellae to a microemulsion and then to macrophase-separated domains as ϕH increased. The phase transitions depended weakly on χN and α in the range of 12.7 ≤ χN ≤ 36.7 and 0.20 ≤ α ≤ 0.99. The periods of swollen lamellae and microemulsions (L B) were determined as a function of ϕH and α and were well described empirically with L B = L 0/(1 − ϕH)β, where L 0 is the natural period of pure block copolymer and β is a parameter that depends linearly on α with values ranging from ∼0.5 to 1.5.

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Section: Resultsmentioning

confidence: 99%

Phase Behavior and Dimensional Scaling of Symmetric Block Copolymer−Homopolymer Ternary Blends in Thin Films

et al. 2009

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“…This technique has been mainly used for structural investigations due to its 3D visualization capability. 18,77,78,[82][83][84][85][86][87][88][89][90] Figure 9a shows one of the representative reconstructed 3D images of the microphase-separated structure showing the gyroid (G) morphology. It is formed in poly(styreneblock-isoprene-block-styrene) (SIS) triblock copolymer.…”

Section: Some Examples and Perspective Of Polymer Nanostructure Studimentioning

confidence: 99%

Transmission Electron Microtomography and Polymer Nanostructures

2010

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This Perspective summarizes the recent advances and perspective in three-dimensional (3D) imaging techniques and their applications to polymer nanostructures, e.g., microphase-separated structures of block copolymers. We place particular emphasis on the method of transmission electron microtomography (TEMT). As a result of some recent developments in TEMT, it is now possible to obtain truly quantitative 3D images of polymer nanostructures with subnanometer resolution. The introduction of scanning optics in TEMT has made it possible to obtain large volumes of 3D data from a micrometer thick polymer specimens using conventional electron microscopes at relatively low acceleration voltage, 200 kV. Thus, TEMT covers structures over a wide range of thicknesses from a few nanometers to several hundred nanometers, which corresponds to quite an important spatial range for hierarchical polymer nanostructures. TEMT provides clear 3D images and a wide range of new structural information, which cannot be obtained using other methods, e.g., conventional microscopy or scattering methods, can be directly evaluated from the 3D volume data. In addition, when combined with other characterization methods, e.g., scattering and computer simulations, TEMT can yield even better results. The single chain conformation of block copolymers inside microdomains may be virtually visualized by TEMT. TEMT is a versatile technique that is not only restricted to polymer applications but can also be used as a powerful characterization tool in energy applications, e.g., fuel cells, etc.

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“…The applications, such as photonic crystals, 4 separation membranes, 5 membrane reactors, [6][7][8][9][10] and solar cells, 11 have all been well demonstrated. Order-order phase transitions from hexagonally perforated layer (HPL) phase, 12,13 sponge phase, 14 C phase, [15][16][17][18] or L phase 12,13,19,20 to G phase have been found; the transition mechanism was demonstrated to be a nucleation and growth process. [21][22][23] The phase transition may take action upon thermal annealing and temperature variation.…”

Section: Introductionmentioning

confidence: 99%

Single Helix to Double Gyroid in Chiral Block Copolymers

et al. 2010

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An order−order phase transition of chiral block copolymers (BCPs*) from single helix to double gyroid (H* → G) through a nucleation and growth process was demonstrated. The H* and G phases can be obtained by solution casting from fast and slow solvent evaporation, respectively, suggesting that the H* phase is a metastable phase. Consequently, the coexistence of H* and G phases can be found in the solution-cast samples from intermediate solvent evaporation. To truly examine the transition mechanism of the H* → G, electron tomography was carried out to directly visualize the morphological evolution in real space, in particular, the transition zone at interface. Unlike the mechanisms for the transitions of block copolymers (BCPs) by considering the interdomain spacing matching, a significant mismatch in the lattices for the H* → G was found. Consequently, the transition may require an adjustment on the geometric dimensions to justify corresponding lattice mismatch. As a result, the morphological observations from electron tomography offer new insights into BCP phase transitions.

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Front Cover: Macromol. Rapid Commun. 17/2006

Abstract: Front Cover: A block copolymer/homopolymer (AB/hA) blend exhibits coexisting bicontinuous morphologies, one ordered and the other disordered. Transmission electron microtomography is used to analyze the 3D features of both morphologies (right images), and complementary

Cited by 6 publications

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Phase Behavior and Dimensional Scaling of Symmetric Block Copolymer−Homopolymer Ternary Blends in Thin Films

Phase Behavior and Dimensional Scaling of Symmetric Block Copolymer−Homopolymer Ternary Blends in Thin Films

Transmission Electron Microtomography and Polymer Nanostructures

Single Helix to Double Gyroid in Chiral Block Copolymers

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