Morphology spherical

Morphology Spherical Spherical Spherical Spherical Spherical Spherical... 

Fig. 2 Self-assembled block-copolymers aggregates of different morphologies spherical (i = 3), cylindrical (i = 2), lamellar (i = 1). Hydrophobic blocks B and polyelectrolyte blocks A form the core and the corona of the micelle, respectively...

Pedersen and coworkers [74, 80, 81, 86] have modified Eq. 78 based on Monte Carlo simulation results from chains exhibiting excluded volume effects. Written in terms of a micelle constituted of a A-B block copolymer, this can be written independently of morphology (spherical, ellipsoidal, or cylindrical) ... 

Therefore, we can synthesize aluminum nitride powders in a wide range of sizes - from nanosized to micron powders with various morphologies (spherical, laminar, thread- and needle-like) by changing aluminum combustion temperature, nitrogen pressure, and the initial mixture composition. Each size can be considered as optimum for specific appUcations. 

In both theories, the concentration of surfactant influences the morphology. In fact, a particular morphology (spherical micelles, cylinders, or lamellas) occurs at a certain concentration range. Ruokolainen et al. estimated that the lamellar morphology is highly preferable for polymer/surfactant systems in the wide concentration range [38]. 

Figure 9 Self-assembled block copolymer aggregates of different morphologies spherical (/=3), cylindrical ( =2), lamellar ( =1). Insoluble B blocks and soluble A blocks are forming the core and the corona, respectively.

CUSO4 Glucose Yes Glucose itself (optimization of its cone, proved to show an effect on the Cu NP morphology) Spherical (-5 or 20nm), rod-like (diameter 50nm, aspect ratio -2.5) [110] (2006)... 

When monomers of drastically different solubiUty (39) or hydrophobicity are used or when staged polymerizations (40,41) are carried out, core—shell morphologies are possible. A wide variety of core—shell latices have found appHcation ia paints, impact modifiers, and as carriers for biomolecules. In staged polymerizations, spherical core—shell particles are made when polymer made from the first monomer is more hydrophobic than polymer made from the second monomer (42). When the first polymer made is less hydrophobic then the second, complex morphologies are possible including voids and half-moons (43), although spherical particles stiU occur (44). 

A weU-known feature of olefin polymerisation with Ziegler-Natta catalysts is the repHcation phenomenon ia which the growing polymer particle mimics the shape of the catalyst (101). This phenomenon allows morphological control of the polymer particle, particularly sise, shape, sise distribution, and compactness, which greatiy influences the polymerisation processes (102). In one example, the polymer particle has the same spherical shape as the catalyst particle, but with a diameter approximately 40 times larger (96). 

Thermoplastic Elastomers. These represent a whole class of synthetic elastomers, developed siace the 1960s, that ate permanently and reversibly thermoplastic, but behave as cross-linked networks at ambient temperature. One of the first was the triblock copolymer of the polystyrene—polybutadiene—polystyrene type (SheU s Kraton) prepared by anionic polymerization with organoHthium initiator. The stmcture and morphology is shown schematically in Figure 3. The incompatibiHty of the polystyrene and polybutadiene blocks leads to a dispersion of the spherical polystyrene domains (ca 20—30 nm) in the mbbery matrix of polybutadiene. Since each polybutadiene chain is anchored at both ends to a polystyrene domain, a network results. However, at elevated temperatures where the polystyrene softens, the elastomer can be molded like any thermoplastic, yet behaves much like a vulcanized mbber on cooling (see Elastomers, synthetic-thermoplastic elastomers). 

Information on the morphology of the nanohybrid sorbents also was revealed with SEM analysis. Dispersed spherical polymer-silica particles with a diameter of 0.3-5 pm were observed. Every particle, in one s turn, is a porous material with size of pores to 200 nm and spherical particles from 100 nm to 500 nm. Therefore, the obtained samples were demonstrated to form a nanometer - scale porous structure. 

The outstanding morphological feature of these rubbers arises from the natural tendency of two polymer species to separate one from another, even when they have similar solubility parameters. In this case, however, this is restrained because the blocks are covalently linked to each other. In a typical commercial triblock the styrene content is about 30% of the total, giving relative block sizes of 14 72 14. At this level the styrene end blocks tend to congregate into spherical or rod-like glassy domains embedded in an amorphous rubbery matrix. These domains have diameters of about 30 nm. 

The various studies of shock-modified powders provide clear indications of the principal characteristics of shock modification. The picture is one in which the powders have been extensively plastically deformed and defect levels are extraordinarily large. The extreme nature of the plastic deformation in these brittle materials is clearly evident in the optical microscopy of spherical alumina [85B01]. In these defect states their solid state reactivities would be expected to achieve values as large as possible in their particular morphologies greatly enhanced solid state reactivity is to be expected. 

The strong influence of morphology and mixing is well illustrated with the composite particle investigation. These particles were composed of a nickel shell coated on spherical aluminum particles by hydrogen reduction in aqueous metal salt solution. The overall ratio of material in a particle was about 80 wt% Ni and 20 wt% aluminum. With these particles, the ratio of reactants was approximately the same as in the mixed powders, but the morphology of the reactants is radically different. 

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