Fluoro-hectorite

FIG. 4 Experimental (vertical bars) and simulated (symbols) values of the d-spacings for aUcy-lammonium-exchanged clay at three different cation exchange capacities (CECs) (a) SWy2 mont-morillonite, CEC = 0.8 meq/g (b) AMS montmorillonite (Nanocor), CEC = 1.0 meq/g (c) fluoro-hectorite (Dow-Corning), CEC = 1.5 meq/g. (Erom Ref. 30.)... 

The enhancement in catalytic activity of cations such as Zn(II) which has been achieved both through ion exchange as well as deposition of Zn(II) salts onto clay surfaces led to studies of the acidity and catalytic activity of such ions when incorporated directly into the lattice sites of synthetic clay minerals. Luca et al. showed that Lewis acid sites are generated on Zn2+-substituted fluoro-hectorite.27 The Zn2+-substituted fluorohectorite was synthesised by a sol-gel route. The sol was allowed to crystallise in a Parr autoclave at 250 °C for 24 hours. The Lewis acid sites were identified as Zn2+ at the edges of the fluorohectorite crystallites and were active towards the Friedel-Crafts alkylation of benzene with benzyl chloride. 

Xu et al. heterocoagulated cationic PMMA latex particles of an estimated 150-200 nm in diameter with various clays, Montmorillonite (GelWhite GP and Cloisite Na+) and (fluoro)hectorites (Laponite RD, RDS, B, S, JS), having plate dimensions between 25 and 600 nm. No details on the stable colloidal armored structures were reported. Mass coagulation was induced in order to obtain a nanocomposite bulk material, which was further analyzed [23]. Chen et al. [24] added Ti02 and SiOi/TiOi nanoparticles with a positive surface charge at a very low pH of 0-2 to both anionic and cationic latexes based on PMMA. A bulk nanocomposite blend was analyzed. 

Wang and Martinez acted as pioneers by reporting the first clay-modified CPE. Afterwards, many other works were based on the use of montmorillonites and sepiolite, " but also bentonites, vermiculites, ° kaolinites, kaolin, (fluoro)hectorites, muscovite, and some other natural smectite clays. - ... 

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