  The stability of alkane-in-water nanoemulsions during the sub-stationary
regime is studied by means of Emulsion Stability Simulations (ESS). The effects
of Ostwald ripening, flocculation, coalescence, gravity, and hydration forc- es
are considered. According to these calculations flocculation and coalescence
are predominant during the first few seconds after the preparation of the
emulsion. This favors the generation of a right-skewed Drop Size Distribu- tion
(DSD). As the system evolves, the drops grow larger and more repulsive causing
a slow down of the flocculation process. In the case of dodecane (C12) and
hexadecane (C16) the referred phenomena, reinforce the ripening trend to
subvert the initial DSD variation, producing a meta-stable distribution which
is preserved during several minutes. After this time, Ostwald ripening
dominates: the skirt of the distribution changes progressively from
right-skewed to left-skewed. Consistent with these changes, the cube average
radius of the emulsion increases rapidly at first, but progressively diminishes
generating a concave-downward curve that stabilizes asymptotically. In the case
of dodecane and hexadecane the complete dissolution of the drops promoted by
ripening is prevented at all times due to coalescence. In the case of octane
(C8) a substantial amount of drops is lost by dissolution, forbidding the
attain- ment of a stable DSD. In all cases the molecular exchange only favors a
decrease of the average radius as a function of time. It is the elimination of
drops either by dissolution or coalescence which causes an increase of the
average radius of the emulsion.
