Micellar morphological transformations for a series of linear diblock model surfactants

The concentration induced shape transitions of linear model surfactants, H(x)T(y), on a lattice have been studied using Monte Carlo simulation. It has been found that a sphere to cylinder shape transition is generally found on shortening the hydrophilic part of the surfactant and anticipates an eventual phase transition. Asymmetric surfactants with longer heads than tails (x > y) prefer to form only spherical micelles independent of total surfactant concentration while asymmetric surfactants with longer tails than heads (x < y) form spherical micelles at lower concentration and undergo a shape transition to cylindrical micelles on increasing the total concentration. Finally, in the case of symmetric surfactants with x = y, only the shortest surfactants H1T1 and H2T2 undergo a sphere to cylinder shape transition on increasing surfactant concentration. Longer symmetric surfactants are always found to prefer to form spherical micelles.