Dislocation-controlled perforated layer phase in a PEO-b-PS diblock copolymer

Small angle x-ray analyses show that the shear-induced hexagonal perforated layer phase in a poly(ethylene oxide)-b-polystyrene diblock copolymer cons ists of trigonal (R3(overbar)m) twins and a hexagonal (P6(3)/mmc) structure , with trigonal twins being majority components. Transmission electron micr oscopy reveals that the hexagonal structure is generated through sequential intrinsic stacking faults on the second layer from a previous edge disloca tion line, while the trigonal twins are formed by successive intrinsic stac king faults on neighboring layers due to the plastic deformation under mech anical shear.