Cauliflower structure/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... 

The film formed on the surface usually has an irregular structure of growing spheres of different sizes and is therefore sometimes called a cauliflower structure, e.g.. Figure 11.8. 

The surface morphology of Ni-B and Ni-B-Zn alloy coatings in their as deposited states is presented in Fig. 2. The comparison of SEM images indicates that Ni-B coatings consist of uniform, fine grained and dense deposits (Fig. 2 (a)). A typical cauliflower structure is obtained which is very useful for wear application. The SEM images of Ni-B-Zn alloy coatings reveal the formation of uniform, well crystallized, uniform and dense structure. 

A special case is the formation of the balls of the size from about 200 pm containing deep cavities with the fem-like dendrites formed on the bottom of cavities and more or less dense cauliflower structure on the surface of these balls. Fig. 2.27d. The cross section of such agglomerate is shown in Fig. 2.28b. For some reasons this agglomerate started to grow as a ball, again starting from disperse (in the middle) and finishing with compact deposit at the surface for a reason... 

Fig. 11.2. Rock-inhabiting fungi often demonstrate a specific yeast-like growth pattern. Image shows a fungal colony, isolated from a marble surface in Crimea (Ukraine). The whole structure resembles a cauliflower and is intensively pigmented by melanin. The colony is very compact and mechanically hard and thus capable of producing intense pressure on the surrounding material.

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 number, size, and distribution of holes in 3D foam or the honeycomb-like structures can be easily controlled by the choice of appropriate electrolysis parameters [20, 24, 25]. Also, the size of grains constructing dendrites or cauliflower-like agglomerates formed around holes, as well as the size of channels between small metal grains agglomerates, is controlled by conditions of electrolysis. The cauliflower-like agglomerates and dendrites among holes define the wall width in this structure type. The specific surface area of the 3D foam or the honeycomb-like... 

Scanning electron microscopy was performed on polypyrrole to determine what the surface structure looked like on a magnified view. The surface is rough and has a cauliflower-like appearance. However, the structure is fairly uniform. 

FIGURE 2.29 Schematic presentation of the swelling of a platinum layer (E = -2.5 V versus SCE) of platinized platinum in 0.1 mol.L" TMAI. (a) Initial surface, (b) During the charge process. Thickness of platinum deposit 0.2 pm. In (c) the quantity of charge corresponds to about half of the maximum charge, and in (d) the full charge process was achieved, which permits then to get the cauliflower -like structure. Oxidation by air (Simonet, J., Unpublished results). 

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