Cationic surfactants, silicate treatment

Post-synthesis hydrothermal treatment in salt solution[202] could be a convenient method for pore expansion and silica-wall thickening for improvement of its stability. The pore size and wall thickness vary with the type of anion in the salt and its concentration. The salt effect follows the well known binding strength of the Hofmeister series of anions for the cationic surfactant, N03 > Br > Cl- > SO 2 FT The anion binds with cationic surfactant molecules in solution to shift the equilibrium of surfactant/silicate binding, leading to less surfactant and water in the pore, and hence less pore expansion. 

Other studies have shown that a related mesoporous silicate can be formed via hydrothermal treatment of a layered silicate such as kanemite and the same alkyltrimethylammonium cationic surfactants [31, 32]. Variation of the synthesis conditions results in a fairly ordered porous material denoted as FSM-16 that has physical properties and diffraction data similar to that of MCM-41 [32]. 

The surface functionalization of nanoparticles is an important requirement to control the compatibility between fillers and polymer matrix and as a result the dispersion state of nanofillers. For example, to tune the organophilic character of nanoparticles and promote dispersion within polymers, chemical surface treatments such as cationic exchange, grafting of organosilanes, or the use of copolymers have been extensively practiced (Avalos et al., 2009 Giannelis, 1996 Patel et al., 2007). For example, Ngo et al. (2010) have shown the influence of the chemical nature of the surfactant used for the modification of the layered silicates on polystyrene foam morphologies. Smaller... 

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