466996 A Facile Approach for Simulating Complex Phases in Block Polymers Via Self-Consistent Field Theory

Thursday, November 17, 2016: 4:15 PM
Golden Gate 2 (Hilton San Francisco Union Square)
Akash Arora, Frank S. Bates and Kevin D. Dorfman, Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN

Self-consistent field theory (SCFT) is the primary theoretical framework to study the phase behavior of block polymers. Solving the highly nonlinear self-consistent field equations requires providing guess values of the potential fields that describes the interaction of a single test chain with the mean field created by the other chains in the melt. The equations are then solved iteratively to locate a local free energy minimum. Convergence (or lack thereof) depends strongly on the guess values of the potential fields; the fields should represent the structure well and should be close enough to the desired microphase. We developed a robust, physically informed approach to generate the guess values of the potential fields using information available from experiments: dimensions and type of the unit cell, shape, size and positions of the particles forming the microdomain, and space group symmetry of the microphase. To demonstrate the utility of our approach, we have generated converged SCFT results for the complex Frank-Kasper σ phase observed in poly(styrene-isoprene-styrene-ethylene oxide) (SISO) tetrablock terpolymer. Furthermore, we compare these SCFT predictions to experimental results for SISO tetrablocks, which report an array of sphere-forming phases: body-centered cubic, face-centered cubic, hexagonally closed packed, and Frank-Kasper σ and A15 phases. 

Extended Abstract: File Not Uploaded
See more of this Session: Nanoscale Structure in Polymers
See more of this Group/Topical: Materials Engineering and Sciences Division