Saponite modeling

Fig. 5. Schematic illustration of the conformation of coumarine molecules intercalated into saponite the dl-type (a) and the

Although the possible catalytic applications of PILCs is the subject more extensively studied, large efforts have also been devoted to the characterisation of the microporous structure of these materials. To this end, the application of both classical and novel models based on gas adsorption has been reported in the literature. The adsorption data depend on the internal physical and chemical structure of the solid and on the nature of the adsorbate molecule. Thus, the adsorption results contain information about structural and energetic properties of the materials surface [8]. In the following, the methods considered in this work to investigate the microporous properties of several alumina-pillared saponites are briefly presented. 

In this work, a comparative study of the textural properties developed by the intercalation and pillaring of a saponite with various aluminium oligomers is presented. The adsorption models above summarized have been applied to the nitrogen adsorption at 77 K results in order to evaluate the effect of the oligomer nature and the calcination temperature on the MPSD of the prepared solids. 

Figure 15.11. Tensile modulus of composites made from nylon and different fillers (montmorillonite, saponite, hectorite and mica) vs. N-NMR chemical shifts of model compounds of fillers. [Adapted, by permission, from Usuki A, Koiwai A, Kojima Y, Kawasumi M, Okada A, Kurauchi T, Kamigaito O, J. Appl. Polym. Sci., SS, No.l, 1995, 119-23.]...

By analyzing the ELD spectra of 2- and 4-[4-(dimethylamino)styryl]-l-ethylpyridinium cations on saponite suspended in DMF (Fig. 20), the tilt and roll angles of the dye were found to be controlled by the amount of the intercalated dye as well as the molecular structure (the position of cationic site within the dye) (103). The adsorption models of 4-[4-(dimethylamino)styryl]-l-ethylpyridinium cations on solid saponite are shown in Figure 21. Depending on the coverage, the orientation of 4-[4-(dimethylamino)styryl]-l-ethylpyridinium varied, as shown in Figure 21. The important role of the orientation of the stilbazolium cations will be discussed in a subsequent section. 

Figure 3. Talc, reference model of trioctahedral smectites. A— hexagonal cavities H and S— eventual localization of the negative charges created by isomorphous replacements H—octahedral charges (hectorite) S— tetrahedral charges (saponite).

The very good orientation of the basal planes permits us to obtain much important information by the diffraction method known as oblique diagrams (Zvyagin [1967]).. It is by this method that the beidellite and saponite lattices were determined. It is also this method that showed the difference between the structures of turbostratic smectites and their ideali2 d models—structural distortion (Mering and Oberlin [1967]). 

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