Solvent annealing of striped ellipsoidal block copolymer particles: Reversible control over lamellae asymmetry, aspect ratio and particle surface

LUCILA NAVARRO; ANDREAS THUNEMANN ; DANIEL KLINGER

ACS Macro Letters

American Chemical Society

Lugar: Washington; Año: 2022

2161-1653

Solvent annealing is a versatile tool toadjust shape and morphology of block copolymer (BCP) particles. During thisprocess, polar solvents are often used for block-selective swelling. However, suchwater-miscible solvents can induce (partial) solubilization of one block in thesurrounding aqueous medium, thus causing complex structural variations and evenparticle disassembly. To reduce complexity in morphology control, we focused ontoluene as non-polar polystyrene-selective solvent for the annealing of stripedpolystyrene-b-poly(2-vinyl pyridine) (PS-b-P2VP) ellipsoids. The selectivestretching of PS chains produces unique asymmetric lamellae structures, which translateto an increase of particle aspect ratio after toluene evaporation. Completereversibility is achieved by changing to chloroform as a non-selective solvent.Moreover, surfactants can be used to tune block-selective wetting of theparticle surface during the annealing, e.g., a PS shell can protect theinternal lamellae structure from disassembly. Overall, this versatilepost-assembly process enables to tailor the structural features of striped colloidalellipsoids by only using commercial BCPs and solvents.