Complex Spherical Packing Phases in Block Copolymers
报 告 人: 史安昌 教授
所在单位: McMaster University
报告地点: 数学学院三楼会议室
报告时间: 2018-08-20 14:00:00
报告简介:

Spherical packing is an interesting problem in mathematics and physics. In particular, spherical packing is intimately related to the structure of ordered phases. The observation of ordered phases in hard-condensed matter systems such as metallic alloys has a long history in materials physics. In recent years, intricate periodic and aperiodic order has emerged in a host of soft matter systems including supramolecular assemblies, surfactants and block copolymers. The occurrence of complex ordered phases in these diverse systems underscores the universality of emergent order in condensed matter. The richness of the phase behavior is exemplified by block copolymers. Recent experimental and theoretical studies have revealed that non-classical ordered phases, such as quasicrystals and the Frank-Kasper phases, could emerge from block copolymers as equilibrium or metastable morphologies. As such, block copolymers provide an ideal system to study the origins and stability of periodic and aperiodic order in condensed matter physics. We have examined the occurrence of complex spherical packing phases in block copolymer systems using the self-consistent field theory. Our study reveals that one key mechanism of forming complex spherical phases is the conformational asymmetry of the blocks. Furthermore, we have predicted that the segregation of different polymeric species in block copolymer blends provides another mechanism to stabilize spherical packing phases with very different sized-spherical domains. In my presentation, I will summarize recent theoretical and experimental progresses on this fascinating topic and discuss possible future research directions.

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主讲人简介:
An-Chang Shi is a professor of physics at McMaster University. He received his B.Sc. in physics from Fudan University in 1982 and his Ph.D. in physics from University of Illinois at Urbana-Champaign in 1988. From 1988 to 1992 he was a Post-Doctoral Fellow and Research Associate at McMaster University. He joined Xerox Research Centre of Canada as a Member of Research Staff in 1992 and moved to McMaster University as an Associate Professor in 1999. He was promoted to Professor in 2004. Dr. Shi received a Premier’s Research Excellent Award in 2000 and was elected to Fellow of American Physical Society in 2010. In 2007, he was appointed as a Changjiang Visiting Professor at Fudan University. Dr. Shi has worked on a wide range of topics in theoretical condensed matter physics, including crystal shapes, superconductivity and soft matter theory. His current research focuses on the development of theory for inhomogeneous polymeric system, the investigation of phase diagrams of block copolymers, and the study of kinetic pathways of transitions between stable and metastable phases.