Interactions Between Micelles in Nematic Lyomesophases

Abstract

Interactions between micelles are analyzed, taking into account Coulombian repulsion, van der Waals attraction and excluded volume, including the water solvation shell bound to the micelles. Curves of interaction energy and force are obtained as a function of the distance between micelles for planar and cylindrical micelles for specific nematic lyomesophases, having the fraction α of ionized polar groups as parameter. It is verified that for both geometries the attractive interaction is always larger than Coulombian repulsion for α ≤ 0.1; the high ionic strength of the medium leads to screening of the micelles since α values are smaller than this limit. Therefore, the systems are in flocculation conditions, with behavior determined by the interplay of the net attractive interaction, the amount of bound water giving the length of the excluded volume interaction and thermal agitation. Possible formation of aggregates of micelles is discussed in view of the results obtained.