Multicompartment microparticles of SBM triblock terpolymers: Morphological transitions through homopolymer blending

Block copolymers (BCPs) have recently been explored in spherical confinement to form internally structured microparticles. While the behavior of AB diblock copolymers in confinement is comparably well studied, knowledge on confined ABC triblock terpolymers is still rather sparse. The latter are especially interesting as the third block allows the formation of a broader variety of multicompartment microparticles (MMs), but their synthesis is often realized through sequential polymerization, which can be work intensive and challenging. Here, we demonstrate that blending linear ABC triblock terpolymers with homopolymers is a versatile and straightforward method to tune the microphase behavior in MMs. We systematically blend polystyrene-block-polybutadiene-block-poly(methyl methacrylate) (SBM or PS-b-PB-b-PM) with homopolymers of hPS, hPB, or hPM, to study the feasibility of this approach to replicate specific morphologies or access new ones. We utilize Shirasu Porous Glass (SPG) membrane emulsification and evaporation-induced confinement assembly (EICA) to produce narrowly size-dispersed MMs with defined inner structure. We analyze the MMs with dynamic light scattering (DLS), as well as transmission and scanning electron microscopy (TEM, SEM). We show that the resulting blend morphologies can be identical to those of the unblended SBM at same composition and that, depending on the location in the ternary microphase diagram, one SBM morphology can be converted into multiple different morphologies.

Graphical Abstract