Symmetric Diblock Copolymers in Cylindrical Confinement: A Way to Chiral Morphologies?

SCHNEIDER, LUDWIG; VEGA, DANIEL; GEORG LICHTENBERG; MÜLLER, MARCUS

Chicago

Encuentro; March Meeting of the American Physical Society; 2022

American Physical Society

Structure formation is induced by quenching the incompatibility, xN, from a disordered morphology. If the surfaces of the cylindrical confinementdo not prefer one component over the other, we observe that stacked lamellae, with their normals along the cylinder axis, are the preferredmorphology. Kinetically, this morphology initially forms close to the cylinder surface, whereas the spontaneous, spinodal microphase-separation inthe cylinder's interior gives rise to a microemulsion-like morphology, riddled with defects and no directional order. Subsequently, the orderedmorphology at the cylinder surface progresses inward, pervading the entire volume.In case that the cylindrical pore is only partially filled, the additional confinement along the cylinder axis generally gives rise to incommensurabilitybetween the equilibrium spacing of stacked lamellae and the cylinder height. To accommodate this mismatch, the lamella normals will tilt awayfrom the cylinder axis and generate helices of lamellae at the surface of the cylinder. Again, this order progresses from the cylinder surface inward,generating a chiral morphology.Since the spacing between the internal AB interfaces decreases upon approaching the helix center, the concomitant stress results in a decrease inthe number of lamellae, and the formation of unique dislocation defects. This type of chiral defect morphology is reproducibly formed by thekinetics of structure formation in partly filled cylindrical pores with nonpreferential surfaces and may find applications in photonic applications