How the Type of Cosurfactant Impacts Strongly on the Size and Interfacial Composition in Gemini 12-2-12 RMs Explored by DLS, SLS and FTIR Techniques.

CUENCA E; FALCONE R.D.; SILBER J.J.; CORREA N M

JOURNAL OF PHYSICAL CHEMISTRY B - (Print)

AMER CHEMICAL SOC

Lugar: Washington; Año: 2016 vol. 120 p. 467 - 476

1520-6106

The limited amount of information aboutreverse micelles (RMs) made with gemini surfactants, theeffect of the n-alcohols in their interface, and the waterentrappedstructure in the polar core motivated us to performthis work. Thus, in the present contribution, we use dynamiclight scattering (DLS), static light scattering (SLS), and FT-IRtechniques to obtain information on RMs structure created,w i t h t h e g e m i n i d i m e t h y l e n e - 1 , 2 - b i s -(dodecyldimethylammonium) bromide (G12-2-12) surfactantand compare the results with its monomer: dodecyltrimethylammoniumbromide (DTAB). In this way, the size of theaggregates formed in different nonpolar organic solvents, theeffect of the chain length of n-alcohols used as cosurfactants,and the water-entrapped structure were explored. The data show that the structure of the cosurfactant needed to stabilize theRMs plays a fundamental role, affecting the size and behavior of the aggregates. In contrast to what happens with the RMsformed with the monomer DTAB, water entrapped inside G12-2-12 RMs displays different interaction with the interfacedepending on the hydrocarbon chain length of the n-alcohol used as cosurfactant. Thus, n-pentanol and n-octanol molecules arelocated in different regions in the RMs interfaces formed with the gemini surfactant. n-Octanol locates at the RMs interfaceamong the surfactant hydrocarbon tails increasing the water−surfactant polar headgroup interaction. On the other hand, npentanollocates at the RMs interface near the polar core, limiting the interaction of water with the micellar inner interface andfavoring the water−water interaction in the polar core.