Studies On Properties Of CTAB-SDS And Synthesis Of CaCO₃ In Mixed Reverse Micelles Of SDS-nonionic Surfactants

Catanionic systems show strong synergism in their solutions and display physicochemical properties which differ distinctly from those of individual surfactants, due to their electrostatic interaction between oppositely charged head groups. However their equimolar mixtures invariably result in precipitates in water even at low concentration. To the best of our knowledge, the relationship of surface acitivity of catanionic surfactant with temperature has not been revealed, and the catanionic surfactant has not been employed in organic reaction also.In this work, surface tensions of equimolar cetyl trimethylammonium bromide-sodium dodecyl sulfate (CTAB-SDS) at different temperatures were determined and compared with those of corresponding individual surfactants. With temperature increasing, the increase of surface activity of CTAB and SDS is very small, however the surface activity of CTAB-SDS mixture increases a lot, which is slightly higher than that of CTAB or SDS at high temperature 90°C. It can be attributed to the changed weak electrostatic interaction. A reasonable explanation supported by solubility experiments was proposed. Based on these results, equimolar CTAB-SDS was used in oxidations of toluene derivatives by potassium permanganate. Its favorable role to oxidative yields of toluene derivatives was investigated by retrieving the products through mimicking the reaction conditions, and by emulsifying the toluene derivatives at 90°C. The contact of toluene derivatives with water can be improved by CTAB-SDS. This gives the reasonable explanation of better oxidative yields of toluene derivatives catalyzed by CTAB-SDS than by CTAB and SDS.Besides, syntheses of CaCO₃ by surfactants have aroused our interesting. To the best of our knowledge, mixed reverse micelles of SDS-nonionic surfactants haven't been used as template in synthesis of CaCO₃. So syntheses of CaCO₃ crystals in reverse micelle solutions containing 1-(1,1,3,3-tetramethylbutyl)-4-hydroxypolyethoxybenzene or poly-oxyethylenated alcohols (Tx-100 or AEO₉), SDS and their equimolar mixture were carried out at room temperature respectively. The crystalline of CaCO₃ is changed from calcite at low concentrations to vaterite at high concentrations of SDS and Tx-100, which opposite to that observed in Tx-100-SDS and AEO₉-SDS. Different morphologies of CaCO₃ were...