Development of Shape-Tuned, Monodisperse Block Copolymer Particles through Solvent-Mediated Particle Restructuring

Controllability of the shape, size, and internal structure of block copolymer (BCP) particles as well as their uniformity is crucial to determine their functionality in the practical applications. Here, we demonstrate the particle restructuring by solvent engineering (PRSE) strategy to produce monodisperse particles using functional BCPs with well-defined structure. Importantly, the advantage of PRSE is the general applicability to various types of functional BCPs including polystyrene-block-poly(1,4-butadiene) (PS-b-PB), polystyrene-block-polydimethylsiloxane (PS-b-PDMS), and polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP). PRSE starts with producing monodisperse BCP spheres in a wide range of particle size using membrane emulsification, followed by transformation to shape-anisotropic BCP particles by solvent annealing. Monodispersity of particle size was maintained during the PRSE, and the shape transformations to prolate and oblate ellipsoids were successfully achieved. PRSE was also effective in controlling the aspect ratio (AR) of the particles, which was supported by theoretical calculation for describing the particle elongation. Further investigation on the kinetics during the PRSE revealed that the morphology transformation was driven by reorientation of BCP domains.