Organic ammonium cation exchange, clay

Exchange of organic ammonium cations. Exchange selectivity of monovalent alkyl ammonium cations in montmorillonites (40-41) and octahedrally substituted synthetic clay minerals (laponite) increases with their chain length (42) and along the series... 

Different types of fillers are utilized, the most common is a nanoclay material called montmorillonite—a layered smectite clay. Clays, in a natural state, are hydrophilic while polymers are hydrophobic. To make the two compatible, the clay s polarity must be modified to be more "organic" to interact successfully with polymers (Hay Shaw, 2000 Ryan, 2003). One way to modify clay is by exchanging organic ammonium cations for... 

Use of organic templates In the current preparation of a new series of microporous crystals, organic templates are often used. Organic chemicals are also used in the preparation of pillared clays to control the pore sizes and the porosity as follows The interlayer cations of silicate layer are exchanged with positively charged sol particles, and then a part of the sols are exchanged with organic template cations such as octadecyl trimethyl ammonium (OTMA). 

The oxidation of various sulfides 424 with iodosylbenzene in the presence of catalytic amounts of quaternary ammonium bromides affords the respective sulfoxides 425 in high yields (Scheme 3.171) [521]. The best catalytic effect in this reaction is observed when oxidation is carried out in a nonpolar solvent (toluene, hexane, dichloromethane) in the presence of trace amounts of water and 10 mol% of cetyltrimethylammonium bromide (CTAB). Iodosylbenzene can also be activated in the solid state by pulverization with natural clays or silica gels [522, 523], The oxidation of various alkyl aryl sulfides with (PhIO) supported on natural (montmorillonite, KSF and bentonite clays) as well as cation-exchanged KlO-montmorillonite clays affords sulfoxides in excellent yields. A mechanism involving depolymerization of (PhIO) by the acidic SiOH sites on the clay is proposed for this reaction [522], Organic sulfides are also selectively oxidized to sulfoxides by the solid reagent system PhI(OAc)2-alumina [524], or by Phl(OAc)2 in water in the presence ofKBr [525],... 

In their search for the development of PBFnano-composite materials, Hsu et al. prepared organically modified Montmorillonite MMT (m-MMT) by a cation-exchange reaction between Na+-Montotrillonite (Na+-Mont) clay and an ammonium salt of dodecyl-amine [46]. This MMT was used as a nanofiller in... 

In the in-situ polymerization technique, the cations in the intergallery space of the clay are exchanged to organic ammonium salts (monomers or initiators), which leads to the expansion of the gap between the clay platelets. The in-situ polymerizations are conducted between the intercalated layers. Various different polymerization technologies were employed for preparing polymer clay... 

---