Formation and self-association of host-guest complexes between βCD and nonionic surfactants Brij

Hierarchical assembly of pH-responsive surfactant–cyclodextrin complexes

“…The evaluation of the systems' behaviour as a function of the degree of ionization confirmed the role of the electrostatic repulsion in directing the assembly of the inclusion complexes. In this context, the present pH responsiveness of the system provided by the alkyl ethylene oxide carboxylic acids differs from the previously investigated cyclodextrin-surfactant inclusion complexes, in which only ionic or nonionic surfactants were applied mainly with β -cyclodextrin 18,30,42 . To employ a weakly acidic alkyl ether carboxylic acid, which combines the characteristics of both ionic and nonionic surfactants, allowed us the possibility to systematically change the degree of charge of the surfactant without changing the chemical nature of the guest molecule.…”

“…However, the encapsulation of both hydrophobic and hydrophilic moieties was observed for the former, while for the latter, only the encapsulation of the hydrophobic moiety was reported. 30,31…”

“…Inclusion complexes of β CD with Brij surfactants, also above the cmc, and Triton-100, in concentrations below the cmc, presented similar thermodynamic behaviour. However, the encapsulation of both hydrophobic and hydrophilic moieties was observed for the former, while for the latter, only the encapsulation of the hydrophobic moiety was reported 30,31 .…”

“…However, the encapsulation of both hydrophobic and hydrophilic moieties was observed for the former, while for the latter, only the encapsulation of the hydrophobic moiety was reported. 30,31 3.1.2 Volumetry. The inclusion complexation mechanism of a guest into the CD cavity is related to the spatial/geometric and energetic aspects via non-covalent interactions, such as electrostatic, van der Waals, hydrophobic, charge-transfer interactions and hydrogen bonding.…”