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McMaster University

Brockhouse Institute Seminar

SPEAKER Prof. Weihua Li, Fudan University
TOPIC Mesocrystals Self-Assembled from Block Copolymers 

The spherical phases self-assembled from block copolymers resemble the familiar space-group symmetry of the solid crystals. Accordingly, the spherical domains could be regarded as artificial macromolecular atoms (AMAs), whose size is at the typical mesoscale length. However, the AMAs are also remarkably different from the atoms. In contrast to the solid atoms, the AMAs are easily deformable and could even be created or destroyed. Furthermore, the packing of the AMAs is dictated by the competition of the entropy and the enthalpy, whereas the packing of the atoms is mainly determined by the interaction potential. Despite these differences, an interesting question is whether the self-assembly of block copolymers could lead to the formation of many of the ordered phases with the same space-group symmetries of the solid crystals but at the mesoscale. I will present our recent self-consistent field theory (SCFT) studies on the formation of rich crystal phases, including single and binary crystal phases, from experimentally synthesized as well as theoretically designed block copolymer systems. For single crystals, the Frank-Kasper phases are observed besides the classical FCC and BCC phases. For binary crystals, more than a dozen binary crystal phases with the symmetry of the ionic crystals are predicted. The self-assembly mechanism of these crystal phases is unveiled by taking advantage of the ability of SCFT to accurately calculate the free energy and the distribution of the segments.

Dr. Weihua Li is a full professor in the Department of Macromolecular Science at Fudan University in Shanghai, China. His research focuses on theoretical study of the self-assembly of block copolymers. He received his bachelor degree in Physics in 1999 and Ph.D in Theoretical Physics in 2004 from Shanghai Jiao Tong University in China. After his PhD, Dr. Li joined St. Francis Xavier University in Canada as a postdoctoral fellow with Professor Robert A. Wickham, and started his research on the self-assembly of block copolymers. In 2006, he joined Professor An-Chang Shi’s group as a postdoctoral fellow at McMaster University. He moved to a faculty position at Fudan University in 2007 and established an active theoretical polymer physics group there since then.

DATE Monday, May 01, 2017
TIME 11:00 am

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