The Process-Directed Self-Assembly of Block Copolymer Particles.

We explore the kinetic paths of structural evolution and formation of block copolymer (BCP) particles using dynamic self-consistent field theory (DSCFT). We show 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, χ AB ) and the selectivity of solvent towards 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, we identify 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. Our findings lead to an effective way of tailoring nanostructure of BCP particles for various industrial applications. This article is protected by copyright. All rights reserved.