Hierarchical Self-Assembly and Digital Memory Characteristics of Crystalline-Amorphous Brush Diblock Copolymers Bearing Electroactive Moieties

Two series of crystalline amorphous brush diblock copolymers bearing electroactive moieties were newly synthesized by sequential anionic ring-opening copolymerizations of glycidyl derivatives and subsequent selective postfunctionalizations; their homopolymers and analogues were additionally synthesized. Self-assembly structural details and electrical memory behaviors of these polymers in nanoscale thin films were investigated. The diblock copolymers revealed complex hierarchical self-assembly structures depending on the compositions. The self-assembly structure and orientation of the crystalline block chains were severely affected by the geometrical confinement (i.e., size and shape) stemming from microphase separation. Such film morphologies were found to significantly influence the electrical properties; they exhibited electrical properties from p-type permanent memory behavior to dielectric-like behavior. The memory behaviors were governed by the trap-limited space charge limited conduction mechanism combined with ohmic conduction and the hopping paths composed of the electroactive moieties distributed locally.