Physicochemical properties of resorcinol-type calix[4]arenes phosphoric esters having four alkyl side chains in aqueous solution

The physicochemical properties of phosphate esters of resorcinol-type of ca lix[4]arenes([4]Ar5P-R-n; side chain length n = 6, 8, and 12) in aqueous so lutions have been characterized by several techniques including surface ten sion and NMR. It is found that the critical micelle concentrations (cmcs) o f [4]Ar5P-R-n are insensitive against the alkyl side chain length, whereas the polarity of aggregates remarkably depends on the alkyl side chain lengt h. From static light scattering and NMR measurements it is suggested that t he shapes of aggregates of [4]Ar5P-R-n are not globular and the alkyl side chains of [4]Ar5P-R-n gather loosely in the aggregates. The mixed propertie s of [4]Ar5P-R-12 and hexaethyleneglycol dodecylether have also been invest igated. The mixed cmcs are considerably greater than those of the respectiv e surfactant cmcs and the interaction parameter calculated using a modified regular solution theory is + 2.7. These results indicate that the repulsiv e interactions occur in the mixed micelles. (C) 2001 Elsevier Science B.V. All rights reserved.