Sphere-forming diblock copolymers confined in a square well

By means of the mean-field dynamic density functional theory (DDFT), the self-assembly behavior of the sphere-forming diblock copolymers confined in the square well has been studied systematically. Various novel structures are predicted, such as a string of spheres, stacked square bricks, a row of elongated potato-like micelles rotated with respect to each other, a single helix, two staggered helices, well-ordered square array of cylinders, highly ordered body-center-cubic (BCC) spheres, highly ordered face-center-cubic (FCC) spheres and concentric layers. Those morphologies provide the theoretical evidence for the experimental observations. Moreover, some interesting phenomena are found, such as the decrease of the number of layers with the increase of the surface field and the formation of the soft spheres, which can be observed in the experiments. Furthermore, a new order parameter is defined to characterize the degree of micro-phase separation for each kind of microscopic structure, and the key factor in affecting micro-phase separation is discussed.