Self using cosolvents

It was proved that hierarchically porous materials with extremely high surface area could be obtained via a self-formation process using cosolvents. 

Since the start of investigations into asymmetric reactions with enolates it has been known that the reactivity and selectivity observed in enolate chemistry is influenced not only by the base employed, but also by the use of cosolvents such as HMPA, and the addition of metal salts or Lewis acids. [2-4, 11] Lithium enolates, in particular, tend to form aggregates by self-assembly. [3, 4] Decisive contributions to the explanation of this phenomenon and its consequences have been made by Seebach et al. by crystal structure analyses of crystalline lithium enolates [12] up to suggestions regarding the structure of the complexes in solution (Scheme 5). [3, 4, 13]... 

Chem. Descrip. Aliphatic waterborne PU disp., NMP cosolv. (10%) Uses Urethane for wood coatings Features Air oxidative self-crosslinking... 

Polysiloxane-containing copolymers were synthesised and characterised by NMR and elemental analysis and were neutralised by triethylamine. It was shown that the copolymers could be self-emulsified to form emulsions in water, with and without cosolvent PCS (propylene glycol monomethyl ether), which exhibited good defoaming abilities. These copolymers were also used as emulsifiers to emulsify silicone oil in water to form stable oil-in-water emulsions. This emulsion also exhibited defoaming properties, more efficiently than the self-emulsified emulsion of siliconised acrylic copolymer. 18 refs. TAIWAN... 

An interesting application of ionic liquids (ILs) concerns their use in combination with classical surfactants [1,2]. Indeed, they can suitably replace each of the microemulsion components (aqueous phase, apolar phase, and surfactants) conferring peculiar features to self-assembled systems. Indeed, ILs are salts and as such have affinity for water, but they also typically possess a lipophilic moiety, and this means affinity for oils. Depending on their chemical structure, ILs can act as cosolvent either for water or for oil. In addition, when their hydrophilic and hydrophobic nature are both strong enough, a fraction of ILs will reside preferentially at the interface formed by the surfactant, and this can impact dramatically the interfacial physics, drastically changing the microemulsion structure and dynamics. 

Block copolymer self-assembled nanoparticles [13-15] form in selective solvents, that is, solvents for only some of the blocks and precipitant for the others. In the simplest case of a diblock copolymer, core/shell nanoparticles such as micelles or vesicles are formed, the core of which consists of collapsed or weakly swollen solvophobic blocks and the shell (also referred to as the corona) of strongly swollen solvophilic blocks. In the case of amphiphilic micelles in aqueous solutions, water is too strong a precipitant for core blocks, and such polymers are not directly soluble in water (unless the hydrophobic block is very short), and the aqueous solutions have to be prepared indirectly using a cosolvent (a solvent for the core block miscible with water) which can be removed from the solution by dialysis or distillation after the dissolution of the copolymer [16]. 

As exemplified above, the use of water as the solvent for organometallic catalysis is hampered by the low general solubility of both substrates and catalysts in this medium. Possible approaches to solving this are based on i) the use of polar cosolvents that often decrease the green character of the catalytic system or ii) the employment of surfactants that form micelles in water as apolar nano-environments where substrates and catalyst get together and react, often with enhanced activity and selectivity. Micelles are self-assembled devices arising from neutral, anionic... 

The curves of the polarity and donicity indices as functions of the cosolvent mole fractions are generally nonlinear. The deviations AT in terms of Equation 3.42, where Y represents the Dimroth-Reichardt E/30) and the Kamlet-Taft %, a, and p (see Section 3.3.2), then express the properties of the solvent mixture that depend on the self- and mutual-interactions of its molecules. Expressions similar to (3.43) may then be used to fit the experimental AT values. The coefficients of this expression for j.(30) and x are shown in Table 3.17 and those for p and a are shown in Table 3.18, the values being adapted from data in compilations by Marcus [56, 87],... 

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