Effect of pressure in assembly and disassembly of surfactant aggregates

YANIS RICARDO ESPINOSA SILVA, RAUL GRIGERA

Carlos Paz

Workshop; Sociedad Argentina de Biofísica; 2013

UNC

Hydrophobic interaction manifests itself in numerous phenomena, including the processes of selfassembling, formation of micelles and protein folding [1]. We studied the effects of high pressure, temperature and solvent on hydrophobic interactions, responsible for micellization of amphiphilic surfactants, using Molecular Dynamic simulations in a system of sodium dodecyl sulphate (SDS) in water, heavy water and a pure non polar solute (Lennard-Jones) Preliminary results indicate that (i) At pressures around 1-1,5 kbar causes disassembly of the formed micelles. (ii) In the range of the pressure higher than 1,5 kbar, the pressure effects is completely reversed, the number aggregation increases causing a redistribution of surfactant molecules changing the geometry of the aggregates, in agreement with experimental observation. (iii) In Lennard-Jones solvent reverse micelles are formed, due to the lack of hydrophobic interaction. (iv) Thermal analysis indicated than at low temperature the SDS molecules are aligned in parallel, similar to lamellar phase diminishing the solvent accessible surface area; when temperature is increased; the structural transition change producing predominantly micellar configurations with a high aggregation number and high solvent accessible surface area.