Controllability of the shape, size, and internal structure of block copolymer (BCP) particles as well as their uniformity is crucial to determine their utility and functionality in the practical applications. Here, we demonstrate the particle restructuring by solvent engineering (PRSE) strategy that combines membrane emulsification and solvent annealing processes, to produce monodisperse particles using functional BCPs with controlled size, shape, and inner structure. Importantly, the advantage of our PRSE approach 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 (from hundreds of nanometers to tens of several microns) using membrane emulsification, followed by successful transformation to shape-anisotropic BCP particles by solvent annealing under neutral wetting condition. Monodispersity of particle size was maintained during the PRSE, and the shape transformations to both prolate and oblate shaped ellipsoids were successfully achieved. Our approach was effective in controlling the aspect ratio (AR) of particles over wide ranges, from 1.0 - 2.5 and 1.0 - 5.0 for prolate and oblate ellipsoids, respectively. Also, observed AR of the particles was well-supported by theoretical calculation based on the model describing the particle elongation. Further investigation on the shape transformation kinetics during the PRSE revealed that the morphology transformation was driven by reorientation of BCP microdomains, whose kinetics was strongly associated with the overall molecular weight of BCP and the annealing time.
5:00 PM–7:00 PM Apr 23, 2019 (US - Arizona)
PCC North, 300 Level, Exhibit Hall C-E