Clays laponite

Bis(oxazoline)-copper complexes supported on clays were investigated as heterogeneous catalysts in the cyclopropanation reaction (37, 38). Optimal results were obtained from chloride-derived complexes in nitroethane as reaction medium. Laponite clay was found to provide higher selectivities than montmorillonite or bentonite. In every case, the heterogeneous reaction afforded increased amounts of the cis cyclopropane relative to the homogeneous reaction. 

A. Knaebel, M. Bellour, J.-P. Munch, V. Viasnoff, F. Lequeux, and J. L. Harden, Aging behavior of Laponite clay particle suspensions, Europhys. Lett. 52, 73 (2000). 

A stereoselective insertion of phenyldiazoacetate-derived carbene into the a-C-H bond of tetrahydrofuran, catalyzed by a laponite clay-immobilized chiral bis(oxazoline) copper complex, depicted below, was also described <07OL731>. 

Bon, Keddy, and coworkers [109] demonstrated that soft armored polymer latex made via Pickering miniemulsion polymerization [i.e., poly(lauryl acrylate) armored with Laponite clay discs] could be used as a nanocomposite additive in standard poly(butyl acrylate-co-acrylic acid) waterborne pressure-sensitive adhesives (PSAs), leading to marked mechanical property enhancements (see Fig. 13). 

Fig. 13 (a) Comparison of the probe-tack stress-strain curves for the model PBA adhesive in the presence of 2.7 wt% clay-armored soft-hard hybrid particles with the equivalent amount of non-armored PLA (2.45 wt%), Laponite clay discs (0.25 wt%), and a blend of non-armored PLA (2.45 wt%) and Laponite clay (0.25 wt%). (b) Synergistic effect of PLA-nanoclay hybrid particles on the tack energy of the model PSA. 

Bon SAF, Colver PJ (2007) Pickering miniemulsion polymerization using Laponite clay as a stabilizer. Langmuir 23(16) 8316-8322... 

As an extension of the previous study, the CATl complex was also anchored through metal axial coordination onto two APTES modified supports, the mesoporous siliea MCM-41 and the Laponite clay, in order to evaluate the effect of the type of support (nature, chemical stability and textural... 

He, F.-A. and Zhang, L.-M. 2006. Using inorganic POSS-modified laponite clay to support a nickel a-diimine catalyst for in situ formation of high performance polyethylene composites. 

A wide variety of snrfactants including anionic and nonionic are widely used as shown in Table 10.45. Bnilder salts, snch as phosphates, EDTA-Na4, soda ash, and citrates, are also used. Certain special ingredients snch as ammonia or pine oil are product specific and are widely nsed. Alkaline sonrces are added to the formnlations, and they are available from caustic alkali, alkanolamines, silicates, and phosphates. Many hard surface cleaners contain some solvents typically they are alcohol, glycol ethers, or abrasive materials are preferable. Calcium carbonate, laponite clay, silica (Si02), alnmina (Al Oj), and titania (Ti02) are widely used as abrasive agents. 

N. Negrete-Herrera, J.-M. Letoffe, J.-L. Putaux, L. David, E. Bourgeat-Lami, Aqueous dispersions of silane-functionalized laponite clay platelets. A first step toward the elaboration of water-based polymer/clay nanocomposites, Langmuir 2004, 20,1564-1571. 

Drying is also a critical parameter in the preparation of PILCs. Slow drying (or air-drying) allows the clay layers to settle down in an ordered, parallel way (face-to-face stacking). This favors the microporosity and crystallinity of the final PILC. Fast techniques, like freeze-drying, fix the random orientation of pillared clay plates or aggregates to form a card-house structure. This structure also exists for the laponite clay. PILCs dried in this way exhibit a larger meso-porosity, but are less crystalline. 

Fan Q, Shan D, Xue H, He Y, Cosnier S (2007) Amperometric phenol biosensor based on laponite clay-chitosan nanocomposite matrix. Biosens Bioelectron 22(6) 816-821... 

Metal particles are most conveniently grown on the clay mineral surface by displacing the exchangeable cation by precursor transition-metal cations and by subsequent reduction. Au and Ag clusters were obtained in laponite clay mineral of synthetic origin by Aihara et al. [9] using this method with sodium borohydride as a reducing agent. Silver nanoparticles are widely used as photosensitive components [10], as catalysts [11], in photocatalysis [12], and in surface-enhanced Raman... 

Konn C, Morel F, Beyou E, Chaumont P, Bourgeat-Lami E (2007) Nitroxide-mediated polymerization of styrene initiated from the surface of laponite clay platelets. Macromolecules 40(21) 7464—7472... 

For some examples of filled polymer melts that exhibit yield stresses with carbon nanotnbe, talc, and laponite clay fillers, respectively, see... 

The adsorption of gemini cationic surfactants [A], 12-5-12, 2Br on solid surfaces has been investigated. The surfactant 12-2-12, 2Br was less adsorbed than its corresponding monomer, DTAB, on silica [84] and titanium dioxide [85], when the adsorption was expressed in moles of adsorbed dodecyl chain per gram of solid. A similar conclusion was reached for the adsorption of DTAB and 12-2-12, 2Br" on laponite clay [86]. No explanation was provided for these results. The maximum amount of 12-5-12, 2Br gemini surfactant adsorbed on silica was shown to decrease very much as the spacer carbon number was increased from 2 to 10 [87]. 

Esumi et al. showed that in the adsorbed state on silica [84], titanium dioxide [85], and laponite clay [86], the gemini surfactant 12-2-12, 2Br has a lower solubilizing power per mole of dodecyl chain than its corresponding monomer, DTAB, for 2-naphthol. 

---