Alkylammonium surfactants

Cationic alkylammonium surfactants have shown 94% biodegradability [27]. 

Ti-MCM-48 (surface area = 1000-1450 m2/g, pore volume = 0.8-1.1 cm3/g, pore diameter = 2.4-2.7 nm) was synthesized by hydrothermal and postsynthetic grafting techniques from cationic alkylammonium surfactants (22,25,323). 

Controlled evaporation of SUVs and MLVs on substrates has been shown to result in the formation of ultrathin films which retained the regular bilayer structure of vesicles [69, 425-427]. These immobilized bilayers, termed as cast multibilayers , cast multibilayers , or ordered cast (ultrathin) films , have provided an alternative to LB films [425-446]. Alkylammonium surfactants with azobenzene (33) and glutamate (34) functionalities have been used, for example, in the preparation of cast-film-forming SUVs. X-ray diffraction... 

The N2 sorption isotherm measured for MCM-41 is distinctive, being a type IV isotherm, presenting an unusually sharp capillary condensation step (Fig. 9.17). MCM-41 type mesoporous silicas are highly porous, showing BET surface areas exceeding 1000 m g and pore volumes up to 1 cm g The pore sizes usually vary between 2 and 10 nm depending on the alkylammonium surfactant chain length, the presence of... 

Polypropylene (PP) is one of the most widely used plastics in large volume. To overcome the disadvantages of PP, such as low toughness and low service temperature, researchers have tried to improve the properties with the addition of nanoparticles that contains p>olar functional groups. An alkylammonium surfactant has been adequate to modify the clay surfaces and promote the formation of nanocomposite structure. Until now, two major methods, i.e., in-situ polymerization( Ma et al., 2001 Pirmavaia, 2000) and melt intercalation ( Manias et al.,2001) have been the techniques to prepare clay/PP nanocomposites. In the former method, the clay is used as a catalyst carrier, propylene monomer intercalates into the interlayer space of the clay and then polymerizes there. The macromolecule chains exfoliate the silicate layers and make them disperse in the polymer matrix evenly. In melt intercalation, PP and organoclay are compounded in the molten state to form nanocomposites. 

It was shown in the early 1990s that nanoscale porosity of silicas can conveniently be generated in a predictable way using smfactant micelles as templates." This approach can be used to form cylindrical pores (diameter 2-30 nm), " spherical pores (diameter 3-27 nm), and other periodic porous structures. Surfactants that are suitable as mieellar templates include alkylammonium surfactants, oligomeric alkyl-poly(ethylene oxide) surfactants, and block copolymers with poly (ethylene oxide) block(s). " The micelle-templating approach has been extended to some other compositions relevant for the manufacture of on-chip insulations, including polymethylsilsesquioxane (formula unit SiOi 5-./2(CH3)(0H),) and... 

Representative snapshots of montmorillonite of high CEC (143meq/100g) with alkylammonium surfactants H3N+-C H2 +i at equilibrium distance. The formation of partially packed and densely packed alkyl monolayers, bilayers, and pseudo-trilayers can be seen. Head groups are positioned very close to the surface due to hydrogen bonds and, therefore, vertically separated between the two clay layers at equilibrium distance even for short chain length. (Reproduced from Fu, Y.T. and Heinz, H., Phil. Mag., in press.)... 

FIGURE 6.4 Typical silicate modifiers. These alkylammonium surfactants are used to modify layered silicates capable of cation exchange, either in aqueous solution or using a surfactant melt. 

Study [25] concluded that this fire performance is probably due to filler-induced increased char formation, because the reductions in PHRR are roughly comparable for all four composites, despite their morphological variations (ranging from very good nanoscale and mesoscale dispersions for the MMT-based nanocomposites to rather poor dispersions and conventional composite structures for the magadiite-based composites [25]). In addition, when the fire behavior of these PET nanocomposites [25] was compared with that of PS nanocomposites [47] (based on both alkylquinolinium- and alkylammonium-modified MMT), it was suggested that the thermally stable quinolinium surfactants are more effective in fire-resistance improvement than the alkylammonium surfactants [25]. 

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