Cauliflower morphologies

The chemical structure of the counterion may have a profound influence on the morphology and conductivity of the polymer. For instance, polypyrrole made in the presence of dodecyl sulfate is very smooth, dense, stable, and highly conducting, whereas polypyrrole made in the presence of perchlorate ion has a cauliflower morphology and its conductivity is about 100 times lower than with dodecyl sulfate. Apparently long-chain anions have a kind of aligning effect on the polymer chains. Also, anions and other... 

All synthetic M-SHs are obtained as fine white powdo-s. Electron microscopic images (Fig. 10) show the typical cauliflower" morphology of magadiite and... 

SEM investigations show that the morphology of the obtained particles depends on whether uncross-linked PVME and PVME microgels are used. In the case of uncross-linked PVME, small spherical particles in the range of 50-100 nm are formed. If Py is polymerized in water without any stabilizer (without PVME) the particles exhibit a cauliflower-like structure and the dispersion is unstable (Fig. 20a). 

This concept can be also applied for the case of the electrodeposition of copper. As mentioned earlier, the morphology of the copper deposit obtained at cathodic potential of -500 mV/SCE under the parallel field was of cauliflower-like structure (Fig. 12b), while the morphology of the copper deposit obtained without the applied magnetic field had very dendritic structure (Fig. 12a). It is known that dendritic structures are main characteristic of electrodeposition in conditions of full diffusion control, while cauliflower-like structures are a characteristic of a dominant diffusion in mixed control of electrodeposition process.13... 

The morphologies of the copper deposits electrodeposited at an overpotential of 550 mV are cauliflower-like and dendritic ones.68 The size of the cauliflower-like particles did not change with increasing temperature, but the size of sub-particles constituting the cauliflower-like forms which decreased with increasing temperature of electrodeposition. The decrease of the size of sub-particles with increasing temperature can be explained by the well-known dependence of the nucleation rate on temperature,69 which was derived by Volmer and Weber.70... 

The morphologies of the copper deposits electrodeposited at an overpotential of 800 mV are shown in Fig. 40, from which the strong effect of evolved hydrogen on the morphologies of copper deposits is visible. Very porous structures, holes formed due to the attachment of hydrogen bubbles, cauliflower-like forms, and the absence... 

In Chapter 4 by Popov et al., the aspects of the newest developments of the effect of surface morphology of activated electrodes on their electrochemical properties are discussed. These electrodes, consisting of conducting, inert support which is coated with a thin layer of electrocatalyst, have applications in numerous electrochemical processes such as fuel cells, industrial electrolysis, etc. The inert electrodes are activated with electrodeposited metals of different surface morphologies, for example, dendritic, spongy-like, honeycomblike, pyramid-like, cauliflower-like, etc. Importantly, the authors correlate further the quantity of a catalyst and its electrochemical behavior with the size and density of hemispherical active grain. 

The most readily observed structure of PPy samples is the peculiar surface morphology common to all electropolymerized PPy films and coatings. The morphology consists of nodules ranging in size to hundreds of microns and that themselves consist of aggregations of smaller particles. The structure has been referred to as a cauliflower - or fractal -like surface. 

The electrode material has also been found to influence the surface morphology of electrochemically prepared PPy films. In our own work, we used transmission electron microscopy (TEM) to investigate the cross-sectional structure of PPy films prepared on different substrates.165 In all cases, the large surface globules were observed to be the caps of cone-shaped structures that extended to the electrode surface of the PPy him (see Chapter 3). Interestingly, Yoon and coworkers showed that the cauliflower-type surface morphology could be virtually eliminated by carefully polishing the electrode surface.152... 

Several studies have shown that electrochemically prepared films have an inhomogeneous nodular (or cauliflower ) structure.125 A number of studies have reported the morphology of PPy films as a function of various processing variables however, little is known of the mechanism of formation of the nodular structure or the effect of this structure on mechanical properties. 

The B4C surface morphologies of field A and field B were shown in Fig.2. It can be seen that the temperature fields have important effects on the surface morphologies of deposits. Under the role of field A, the surface morphology was crystal-like and coarse. The edges of surface particles were very obvious. However, the surface morphology was cauliflower-like under the role of field B. The cauliflower-like particles consisted of small particles. 

The above results showed that the morphology, composition and microstructure were different under two different temperature fields. Under field A, the deposits were crystal B13C2 with high boron concentration and crystalline-like morphologies. Under field B, the deposits were amorphous boron carbide with low boron concentration and cauliflower-like morphologies. The characteristics of deposits depended on deposition mechanism. It was apparent that there were different deposition mechanisms for boron carbide since the characteristics of deposits were very great different under... 

Under field B, the deposition mechanism can be hypothesized as follows. According to cauliflower-like morphology and amorphous phase, BCI3 and CH4 might be reacted before deposition. Therefore, the following reaction might have occurred during deposition process expect for reaction (1) and (2). 

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