  The kinetic paths of structural evolution and formation of block copolymer
(BCP) particles are explored using dynamic self-consistent field theory
(DSCFT). It is shown that the process-directed self-assembly of BCP immersed in
a poor solvent leads to the formation of striped ellipsoids, onion-like
particles and double-spiral lamellar particles. The theory predicts a
reversible path of shape transition between onion-like particles and striped
ellipsoidal ones by regulating the temperature (related to the Flory-Huggins
parameter between the two components of BCP, \chi_{AB}) and the selectivity of
solvent toward one of the two BCP components. Furthermore, a kinetic path of
shape transition from onion-like particles to double-spiral lamellar particles,
and then back to onion-like particles is demonstrated. By investigating the
inner-structural evolution of a BCP particle, it is identified that changing
the intermediate bi-continuous structure into a layered one is crucial for the
formation of striped ellipsoidal particles. Another interesting finding is that
the formation of onion-like particles is characterized by a two-stage
microphase separation. The first is induced by the solvent preference, and the
second is controlled by the thermodynamics. The findings lead to an effective
way of tailoring nanostructure of BCP particles for various industrial
applications.
