The spherical phases self-assembled by block copolymers resemble the similar space symmetry as the solid crystals. Accordingly, the spherical domains can be regarded as some kind of artificial macromolecular atoms (AMAs), which is at the typical mesoscale length. However, the AMAs are also remarkably different from the atoms beside the size scale. In contrast to the solid atoms, the AMAs are much more deformable, or even created or eliminated. On the other hand, the packing of the AMAs is dictated by the competition of the entropy and the enthalpy, while that of the atoms is mainly determined by the interaction potential. Nevertheless, an interesting question is if we can recast most of the ordered phases from the prototypes of the solid crystals at the mesoscale by the self-assembly of block copolymers. I will present our recent self-consistent field theory (SCFT) studies on the formation of rich crystal phases from experimentally synthesized block copolymers as well as purposely designed block copolymer systems by theory, including single and binary crystal phases. For the single crystal phase, the Frank-Kasper phases are observed besides the classical FCC and BCC phases. For the binary crystal phases, more than ten binary crystal phases with the prototypes of the ionic crystals are predicted. The self-assembly mechanism of these crystal phases is unveiled by taking advantange of the ability of SCFT of accurately calculating the free energy and the distribution of each segment.
About the Speaker
Dr. Weihua Li is a full professor in the Department of Macromolecular Science at Fudan University in China. His research focuses on 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. Then he moved to St. Francis Xavier University in Canada for a postdoctoral research with Professor Robert A. Wickham, who is right now at the University of Guelph. Since then, he has started his research on the self-assembly of block copolymers. In 2006, Weihua moved to McMaster University to work with Professor An-Chang Shi as a postdoctoral researcher. In 2007, he moved back to China to take a faculty position at Fudan University,