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Block copolymers transmission electron

Figure 2 The transmission electron micrographs of samples cast from solution containing 1 wt% of polymer, (a) the block copolymer BCl, and (b) the microsphere, MCI [24]. Figure 2 The transmission electron micrographs of samples cast from solution containing 1 wt% of polymer, (a) the block copolymer BCl, and (b) the microsphere, MCI [24].
Figure 7 The transmission electron micrograph of the block copolymer B1 for blend [36]. Figure 7 The transmission electron micrograph of the block copolymer B1 for blend [36].
Interestingly, this behavior of the reaction mixture can be prevented by employing another principle of particle stabilization steric protection. Inclusion of pegylated comonomer (PEG-AEPD) into the reaction mixture did enable the formation of nonaggregating DNA particles. It also caused the particles to form worm -like structures (as judged by transmission electron microscopy) that have previously been observed with DNA complexes formed from block copolymers of PEL and PEG [98]. [Pg.446]

The use of lightly crosslinked polymers did result in hydrophilic surfaces (contact angle 50°, c-PI, 0.2 M PhTD). However, the surfaces displayed severe cracking after 5 days. Although qualitatively they appeared to remain hydrophilic, reliable contact angle measurements on these surfaces were impossible. Also, the use of a styrene-butadiene-styrene triblock copolymer thermoplastic elastomer did not show improved permanence of the hydrophilicity over other polydienes treated with PhTD. The block copolymer film was cast from toluene, and transmission electron microscopy showed that the continuous phase was the polybutadiene portion of the copolymer. Both polystyrene and polybutadiene domains are present at the surface. This would probably limit the maximum hydrophilicity obtainable since the RTD reagents are not expected to modify the polystyrene domains. [Pg.227]

Recently, Kroeze et al. prepared polymeric iniferter 34 including poly(BD) segments in the main chain [152]. They successfully synthesized poly(BD)-block-poly(SAN), which was characterized by gel permeation chromatography, elemental analysis, thermogravimetric analysis, NMR, dynamic mechanical thermal analysis, and transmission electron microscopy. By varying the polymerization time and iniferter concentration, the composition and the sequence length were controlled. The analysis confirmed the chain microphase separation in the multiblock copolymers. [Pg.94]

Figure 9.3. Characterization of mesoporous Ti02 films templated by Pluronics block copolymers using diverse characterization techniques XRD pattern (a), transmission electron microscope (TEM) image (b), dark-field TEM image (c), and isotherms of Kr adsorption (d).The Pluronic-templated Ti02 films were calcined at 400°C (solid points) and 600°C (open points). The films were prepared according to Alberius et al. (Ref. 14). Figure 9.3. Characterization of mesoporous Ti02 films templated by Pluronics block copolymers using diverse characterization techniques XRD pattern (a), transmission electron microscope (TEM) image (b), dark-field TEM image (c), and isotherms of Kr adsorption (d).The Pluronic-templated Ti02 films were calcined at 400°C (solid points) and 600°C (open points). The films were prepared according to Alberius et al. (Ref. 14).
The phase morphology of block copolymers can also be visualized by transmission electron microscopy. Figure 10.8 shows the lamellar structure of Fluoro-PSB-IX. From diblock copolymers it is well known that the resulting microphase morphology depends on the volume fraction (< >) of the two phases. By simple adjustment of the relative block lengths we are able to synthesize block copolymers with specific structures.1718... [Pg.161]

A controversy has arisen as to whether the observations by POM and those by transmission electron microscopy reflect the same morphological features or not. In fact, Kim et al. [125] demonstrated that the same block copolymer can exhibit different morphologies depending on sample thickness, this being a possible reason for the sometimes contradictory results found in several works. Nevertheless, before this aspect can be properly treated in this section, we present a review of the morphological investigations carried out in semicrystalline ABC triblock copolymers at a nanoscopic scale. [Pg.54]

Goldraich M, Talmon Y (2000) Direct-imaging cryo-transmission electron microscopy in the study of colloids and polymer solutions. In Alexandridis P, Lindman B (eds) Amphiphilic block copolymers self assembly and applications. Elsevier, Amsterdam... [Pg.141]

Some typical transmission electron micrographs of these polystyrene lattices are shown (Sample 2 and Sample 3) in Figure 10.6. The effects ofthe amount of stabilizer S is the relative amount of stabilizer) on the particle size is strong the more stabilizer applied, the smaller the particles are. It must be emphasized that this effective stabilization of nanopowders by our fluorinated block copolymers is not restricted to polymerization processes, but can be generalized to the fabrication of all organic nanopowders in media with low cohesion energy density, e.g., to the dispersion of dyes, explosives, or drugs. [Pg.159]

Transmission electron micrography has, remarkably, been successfully used to image micelles formed by block copolymers in dilute solutions. Price and coworkers used two preparation methods. In the first method (Price and Woods 1973), f reeze etching, a drop of solution was rapidly frozen by quenching in liquid nitrogen. Solvent was then allowed to evaporate from a freshly microtomed surface of the droplet. Finally, a replica was made of collapsed micelles raised proud from the frozen surface. In the second method (Booth et al. 1978), a drop of micellar solution was allowed to spread and evaporate on a carbon substrate, and 0s04 was used to selectively stain one of the blocks. [Pg.16]

Transmission electron microscopy (TEM) has been used to provide a direct image of block copolymer micelles that complements the indirect information obtained from scattering experiments. Because of the technical difficulties of obtaining electron micrographs from solutions it is not employed routinely. Price and co-workers (Booth et al. 1978 Price and Woods 1973) obtained specimens for TEM investigation by two methods. In the first (Price and Woods 1973),... [Pg.136]

The physics of the glass transition in block copolymers are essentially the same as those of homopolymers, and little experimental attention has been devoted to this aspect. Ordered phases in block copolymer melts can be vitrified by cooling below the glass transition temperature of a glassy block, and indeed this is often the method for preparing samples for transmission electron... [Pg.326]


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Transmission electron copolymers

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