Cryogenic Transmission Electron Microscopy Imaging of Vesicles Formed by a Polystyrene−Polyisoprene Diblock Copolymer

Kesselman, Ellina; Talmon, Yeshayahu; Bang, Joona; Abbas, Sayeed; Li, Zhibo; Lodge, Timothy P.

doi:10.1021/ma0510587

Cited by 42 publications

(53 citation statements)

References 16 publications

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“…Hence, C 6 F 14 is a more selective solvent (for PFPO), thus contributing to the formation of larger micelles. This argument has been bolstered by recent measurements of polystyrene–polyisoprene micelles in dialkylphthalates, where morphology changes from spheres to cylinders, and from cylinders to vesicles, were found upon increasing the interfacial tension by varying solvent composition 48–50. When the interfacial tension becomes extremely high, it is possible to enter the superstrong segregation regime, and in this case disk‐like micelles are preferred over cylinders.…”

Section: Resultsmentioning

confidence: 92%

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Zhu

Edmonds

Hillmyer

et al. 2005

J Polym Sci B Polym Phys

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A versatile coupling reaction for the preparation of polybutadiene–poly‐(hexafluoropropylene oxide) (BF) diblock copolymers is described. Six diblock copolymers with different block lengths were characterized by nuclear magnetic resonance spectroscopy and size exclusion chromatography; all six had total molecular weights below 15,000. Microphase separation of the block copolymers in the bulk state was established by small‐angle X‐ray scattering (SAXS) and differential scanning calorimetry. SAXS data suggest that the diblocks are characterized by an unusually large Flory‐Huggins interaction parameter, χ, on the order of 10. However, extraction of χ from the order–disorder transition gave large (order 1) but significantly different values, thereby suggesting that these copolymers are too small and too strongly interacting to be described by block copolymer mean‐field theory. Dynamic light scattering was used to analyze dilute solutions of the title block copolymers in four selective organic solvents; the sizes of the micelles formed were solvent dependent. The micellar aggregates were large and nonspherical, and this is also attributed to the high degree of incompatibility between the two immiscible blocks. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3685–3694, 2005

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Section: Resultsmentioning

confidence: 92%

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Zhu

Edmonds

Hillmyer

et al. 2005

J Polym Sci B Polym Phys

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“…Similar contrast reversal has also been observed in cryo-TEM images of polystyrenepolyisoprene (PS-PI) copolymer aggregates in dialkyl phthalate solvents. [11,31,32] Figure 6 shows a representative progression of the electron beam damage that occurs in the PS-PMMA/BMIM PF 6 samples. The arrows in Figure 6(a) and 6(c) point to two micelles that are distinguishable both before and after the beam damage.…”

Section: Electron Beam Damagementioning

confidence: 99%

Micellization of PS‐PMMA Diblock Copolymers in an Ionic Liquid

Simone

Lodge

2007

Macro Chemistry & Physics

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Three polystyrene‐block‐poly(methyl methacrylate) (PS‐PMMA) block copolymers with varying molecular content have been shown to form micelles when dissolved in the ionic liquid 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIM PF6). The micellar structure was studied via cryogenic transmission electron microscopy and dynamic light scattering, and a morphological transition from spherical to cylindrical micelles was observed upon reduction of the PMMA volume fraction. The possibility of frozen micellar morphology was considered, due to the solution preparation method and high glass transition temperature (Tg) of the PS blocks that form the micellar cores. By comparison of the behavior of a 100 kDa PMMA homopolymer dissolved in both BMIM PF6 and a known good solvent, acetone, it was determined that BMIM PF6 behaves as a good solvent for PMMA. It was also observed that extended exposure to the electron beam during cryogenic transmission electron microscopy could damage the copolymer micelles and result in a reversal of contrast.

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“…Cryo‐TEM is now widely used to study synthetic, biological and medical systems. Originally developed for aqueous systems, it has been also applied successfully in the study of nonaqueous systems (Kesselman et al ., ; Bang et al ., ; Dudkiewicz et al ., ). However, this methodology cannot be used to study highly viscous systems, or those containing objects larger than several hundreds of nanometres (Talmon, ).…”

Section: Introductionmentioning

confidence: 99%

Cryogenic‐temperature electron microscopy direct imaging of carbon nanotubes and graphene solutions in superacids

Kleinerman

Parra-Vasquez

Green

et al. 2015

Journal of Microscopy

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Cryogenic electron microscopy (cryo-EM) is a powerful tool for imaging liquid and semiliquid systems. While cryogenic transmission electron microscopy (cryo-TEM) is a standard technique in many fields, cryogenic scanning electron microscopy (cryo-SEM) is still not that widely used and is far less developed. The vast majority of systems under investigation by cryo-EM involve either water or organic components. In this paper, we introduce the use of novel cryo-TEM and cryo-SEM specimen preparation and imaging methodologies, suitable for highly acidic and very reactive systems. Both preserve the native nanostructure in the system, while not harming the expensive equipment or the user. We present examples of direct imaging of single-walled, multiwalled carbon nanotubes and graphene, dissolved in chlorosulfonic acid and oleum. Moreover, we demonstrate the ability of these new cryo-TEM and cryo-SEM methodologies to follow phase transitions in carbon nanotube (CNT)/superacid systems, starting from dilute solutions up to the concentrated nematic liquid-crystalline CNT phases, used as the 'dope' for all-carbon-fibre spinning. Originally developed for direct imaging of CNTs and graphene dissolution and self-assembly in superacids, these methodologies can be implemented for a variety of highly acidic systems, paving a way for a new field of nonaqueous cryogenic electron microscopy.

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Cryogenic Transmission Electron Microscopy Imaging of Vesicles Formed by a Polystyrene−Polyisoprene Diblock Copolymer

Cited by 42 publications

References 16 publications

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Synthesis and self‐assembly of highly incompatible polybutadiene–poly(hexafluoropropylene oxide) diblock copolymers

Micellization of PS‐PMMA Diblock Copolymers in an Ionic Liquid

Cryogenic‐temperature electron microscopy direct imaging of carbon nanotubes and graphene solutions in superacids

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