Phase and rheological behavior of a gemini cationic surfactant aqueous system

Abstract

The phase behavior of aqueous system of a gemini-type cationic surfactant, N,N′-dodecyl-2-hydroxyl-N,N,N′,N′-tetramethyl diammonium dichloride (simply written as 12-3(OH)-12(2Cl)), has been investigated by various complementary methods. A micellar solution region, a hexagonal liquid crystal phase region and two transition regions in the phase diagram are confirmed by SAXS and polarizing microscopy. Over the concentration range, 10–40 (wt%) of 12-3(OH)-12(2Cl), the viscoelastic properties of 12-3(OH)-12(2Cl) solutions at different temperatures have been determined using steady state and frequency sweep rheological measurements. The results from the FF-TEM study are in good agreement with the predictions from steady shear and dynamic rheology in which the large difference in the rheological behavior between 12-3(OH)-12(2Cl) and 12-3(OH)-12(2Br) at the same conditions might be mainly attributed to the role of the intermolecular hydrogen bonding which occurred between the hydroxyl substituted spacers and chloride counter ion and crystallization water molecule.