Pdi. Fletcher et Dn. Petsev, A MODEL FOR THE TEMPERATURE-DEPENDENT INTERACTIONS IN UNCHARGED DROPLET MICROEMULSIONS, Journal of the Chemical Society. Faraday transactions, 93(7), 1997, pp. 1383-1388
Citations number
31
Categorie Soggetti
Chemistry Physical","Physics, Atomic, Molecular & Chemical
Microemulsions consisting of uncharged droplets generally behave as ha
rd spheres at the solubilisation phase boundary (SPB) where the actual
droplet size is close to the preferred droplet size. As the temperatu
re is changed to move inside the one-phase microemulsion region, exper
imental data suggest that the droplets may either grow or cluster toge
ther due to increasing interdroplet attraction. We present a model in
which it is assumed that droplet growth is absent and that the tempera
ture dependence of the interdroplet interactions arises primarily from
the energy associated with bending the stabilising surfactant monolay
er. At temperatures close to the SPB, the actual curvature of the mono
layer coating the droplets is close to its preferred value and the ene
rgy required to deform the interface is high, with the result that the
droplets behave as hard spheres. Away from the SPB, where the actual
monolayer curvature becomes higher than the preferred value, the energ
y required for deformation decreases and the droplets behave as 'soft'
spheres. This results in an apparent increase in attractive interacti
ons between the droplets. The model shows reasonable agreement with ex
perimental turbidity data for uncharged microemulsions.