Date(s) - 13/09/2006
3:30 pm - 4:30 pm
Title: Confined Self-Assembly of Block Copolymers
Speaker: Dr. An-Chang Shi
Institute: McMaster University
Location: ABB 102
Spontaneous formation of ordered structures from amphiphilic molecules has attracted tremendous attentions in the last decades. Among the many different amphiphilic systems, block copolymers with their rich phase behavior and ordering transitions have become a paradigm for the study of structural self-assembly. For the simplest case of diblock copolymers, which are linear polymers composed of two different sub-chains (A and B blocks), a variety of ordered bulk phases, including lamellae, hexagonally-packed cylinders, body-centered-cubic spheres and a bicontinuous network structure called gyroid, are observed. In a physically confined environment, structural frustration, confinement-induced entropy loss and surface interactions can strongly influence the molecular organization. In particular, it is possible that confinement can lead to unusual morphologies which are not accessible in the bulk, thus providing opportunities to engineer novel structures. For confined asymmetric diblock copolymers, a rich variety of novel morphologies, ranging from helices to toroids to complex networks, is predicted.
The combination of theoretical studies with experiments demonstrates that confined self-assembly of amphiphilic molecules provides a robust method to produce nanoscopic structures which are not accessible in the bulk phases.