Hydrophobic interactions, colloid

Yamaguchi K, Ito M, Taniguchi T, Kawaguchi S, Nagai K (2004) Preparation of core-shell composite polymer particles by a novel heterocoagulation based on hydrophobic interaction. Colloid Polym Sci 282(4) 366-372... 

Adhesion of bacteria to surfaces is believed to be mediated by long-ranging colloidal interactions, which hold bacteria in the close proximity of surfaces, thereby facilitating short-ranging hydrophobic interactions and adsorption of cell surface polymers to the surface. The extent of these interactions, and particularly the hydrophobic ones, depends strongly on the properties of... 

In an aqueous medium these wtermolecular attractive interactions make a strong contribution to biopolymer self-association and inclusion complex formation, as well as to the flocculation of biopolymer-coated colloidal particles. // //Y/molecular hydrophobic interactions commonly influence the level of folding/unfolding of macromolecules as well as their detailed conformations. 

Charged colloids and water-in-oil microemulsions provide organized environments that control photosensitized electron transfer reactions. Effective charge separation of the primary encounter cage complex, and subsequent stabilization of the photoproducts against back electron transfer reactions is achieved by means of electrostatic and hydrophobic interactions of the photoproducts and the organized media. 

It is known that interactions between ionic surfactants and polyions with the opposite charge lead to the formation of soluble colloidal complexes. The polyelectrolyte chain binds to surfactant molecules through Coulombic attractions, and the hydrophobic moieties of the surfactant molecules stabilize the complexes due to hydrophobic interactions in the aqueous solution (Morris and Jennings, 1976 Satake and Yang, 1976 Osica etal., 1977 Fendler, 1982 Hayakawa et al., 1983 Jonsson et al, 1998). 

Fig. 20. Photosensitized H2-evolution from an organized assembly composed of a Pt-colloid stabilized by a positively charged polymer matrice. Charge separation is effected by means of complementary electrostatic and hydrophobic interactions...

Since these interfaces are usually constructed of charged detergents a diffuse electrical double layer is produced and the interfacial boundary can be characterized by a surface potential. Consequently, electrostatic as well as hydrophilic and hydrophobic interactions of the interfacial system can be designed. In this report we will review our achievements in organizing photosensitized electron transfer reactions in different microenvironments such as bilayer membranes and water-in-oil microemulsions.In addition, a novel solid-liquid interface, provided by colloidal Si02 particles in an aqueous medium will be discussed as a means of controlling photosensitized electron transfer reactions. 

It has been established experimentally that whereas mutual coagulation takes place in certain quantitative relationships when various oppositely charged colloidal systems—hydrophile and hydrophobe—interact, quite a different process can take place in the case of other interrelationships the addition of a small amount of a hydrophile colloid to a hydrophobe system... 

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