TEM, cryogenic

Morphology of select star blocks was investigated by transmission electron microscopy (TEM). Films were cast from toluene and annealed for 2 days at 120 °C. Ultra thin sections (-50 nm) of unstained samples were cut by cryogenic microtome techniques. Samples were viewed by a JOEL (JEM-1200EXII) TEM. 

Won Y-Y, Brannan AK, Davis HT et al (2002) Cryogenic transmission electron microscopy (cryo-TEM) of micelles and vesicles formed in water by poly(ethylene oxide)-based block copolymers. J Phys Chem B 106 3354-3364... 

Figure 7.10. Sectioning of a TEM sample using an ultramicrotome instrument. Shown is an ultramicrotome instrument with a built-in nitrogen cryogenic system, used to section samples with a thickness of 25 nm-5 mm.h7l Also shown is a TEM image of polymer capsules that have been sectioned using an ultramicrotome instrument. Image reproduced with permission from Dai, Z. Mohwald, H. Langmuir 2002,18, 9533. Copyright 2002 American Chemical Society.

Summary PDMS-6-PEO short-chain diblock copolymers were prepared via anionic ring-opening polymerization of cyclosiloxanes. Applying this method, various well-defined block copolymers with different compositions were synthesized and their phase behavior was investigated. The polymers predominantly showed lamellar phases in aqueous solutions. At small surfactant concentrations, vesicles were formed, as observed via cryogenic TEM. The aggregates of the diblock copolymers were used for the formation of lamellar thin films, applying the evaporation-induced self-assembly approach. 

The aggregation behavior of selected dibiock copolymers with various compositions was investigated applying several techniques, such as polarized optical microscopy (POM), tensiometry measurements, fluorescence studies, deuterium NMR spectroscopy, SAXS measurements, and cryogenic TEM [4, 5]. In systematic studies we particularly focused on the effect of an increase in the dimethylsiloxane chain length on the aggregation behavior of the investigated surfactants. 

Prolonged exposure of the sample to the electron beam may cause radiation damage particularly in the case of akaganeite (Galbraith et al. 1979). A technique for imaging particles in aqueous suspensions in a supercooled, vitrous state is Cryogenic TEM. It has been applied to Fe oxides by Bailey et al. (1993). 

It is possible to observe the morphologies of the cationic PMETAI stars in solution by cryogenic transmission electron microscopy (cryo-TEM). Figure 1 clearly shows the distinct and well-separated structures in the vitrified solution. In some cases it is even possible to see the silsesquioxane core [28],... 

A technique called cryogenic temperature transmission electron microscopy (cryo-TEM) has been used by biologists for some years but is now also being used by chemists to examine a wide range of samples. CryoTEM involves the fast cooling of a thin film of liquid sample and transferring the sample into the TEM where it is maintained at... 

Cryogenic TEM See Freeze-Fracture Method, Electron Microscopy. 

Storable liquid propellants now receive greater attention than cryogenics. Stoiability refers to a liquid which can be kept for a long time at ambient tem-poratnre in standard containers without any significant loss of material. 

Cryogenic transmission electron microscopy (Cryo-TEM) or cryogenic high resolution transmission electron microscopy (Cryo-HRTEM) involves the observation of samples of vitrified macromolecules. 

The data presented in Figs. 5, 6, 7, and 8 should be considered typical of the lovv-tem-perature mechanical properties of commercial 0.005- and O.OlO-in.-diameter Nb-25 %Zr superconductor wires. In view of the difficulties involved in testing extremely small-diameter wires at cryogenic temperatures, as well as the limited number of samples tested, it would be erroneous to consider the data design minima. As design guide information, however, the data are significant. 

The technique of transmission electron microcopy at cryogenic temperature (cryo-TEM) allowed for the direct visualization of micelles and vesicles of all shapes described... 

---