Invited Talk: Frank Bates Structure and dynamics of tetrahedrally coordinated block copolymer particles*

Since the discovery of the Frank-Kasper (FK) sigma phase in block polymers in 2010 there have been numerous experimental and theoretical reports of various tetrahedral close-packed particle phases in this class of soft matter. This presentation will summarize recent small-angle X-ray scattering (SAXS) and self-consistent mean-field theory (SCFT) results demonstrating the role of core block compatible homopolymer on the formation of the sigma, C14 and C15 phases, along with BCC and HCP structures. Mixtures of A-B and A¢-B¢ type diblocks will also be discussed, where super-cooling a disordered diblock copolymer melt led to the development of a dodecagonal quasicrystalline (DDQC) state, which transformed into the sigma phase after long time annealing. A judicious processing strategy afforded access to aperiodic (DDQC) and periodic (sigma) order in the same system at the same temperatures, providing unprecedented access to comparative X-ray photon correlation spectroscopy measurements, which revealed sizable differences in the associated particle dynamics. SCFT predictions motivated the investigation of compositionally asymmetric A-B and A-C diblock blends by SAXS, where the particle core-forming B and C blocks are thermodynamically incompatible. These most recent results also will be described.

 

Research conducted in collaboration with: Zachary Gdowski, Andreas Mueller, Aaron Lindsay, Ronald Lewis III, Quingteng Zhang, Suresh Narayanan, Timothy. P. Lodge, Kevin D. Dorfman, Mahesh. K. Mahanthappa