engleski

Structure and Dynamics of Vesicles from Symmetrical Double Chain Alkylbenzenesulphonates

Symetrical double-chain sodium 1’-(7)- tridecylbenzensulphonate (7STBS) was prepared by conventional methods from reagent-grade starting materials. Appro-priate symmetrical ketone reacts with phenylmagnesium bromide in Grignard reaction, giving tertiary alcohol A. Hydrogenation of A over palladium in cold acetic acid gives alkyl-substituted benzene, which, upon sulphonation by Doe's procedure, and neutralzation of resulting sulphonic acid, yields sodium salt. The samples were observed at room temperature using a polarized light microscope operated with differential interference contrast optics. In the dilute regime the formation of either lamellar bilayers and multilayers or vesicles were found. It was shown that the particles belong to a multilamellar vesicle phase. The texture observed in the polarization microscope without using the I plate showed the sparcling particles. Particles diameters of freshly prepared systems were found to be 75 - 220 nm relating to the surfactant 0.5 - 7 %, and 150 - 310 nm by aged systems with the surfactants 0.5 - 1.5 %, respectively. The time dependent shift in the vesicle/lamellar phase transition of the macroscopically equilibrated systems could be supposed to be a low energy transition. In addition, dynamic light scattering determination showed that some structural changes occured by aging the samples. The transition between the vesicles and lamellae was governed also by the concentration and temperature change.

liquid crystals ; surfactants ; vesicles

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