The equilibrium phase behavior of multicomponent polymer blends or block copolymers can be accurately described by self-consistent field theory (SCFT) that provides the free energy as a functional of the density field(s). In the course of processing, however, the system often do not reach equilibrium. Instead, the kinetics of structure formation becomes trapped in a metastable state and a description of the kinetics that builds on the accurate SCFT free-energy functional is needed.
The subdiffusive single-chain dynamics on short time scales, however, gives rise to memory effects in the collective dynamics of the density field. Using linear response theory (i.e., dynamic RPA) we compute the Onsager coefficient that relates the chemical potential to a current in dynamic-SCFT. This Onsager coefficient is nonlocal in space and time.
Applications to macrophase separation in blends and microphase separation in block copolymers will be discussed.
Kinetic pathways of block copolymer directed self-assembly: Insights from efficient continuum modeling, J. Rottler and M. Müller, ACS Nano 14, 13986 (2020)
Collective short-time dynamics in multicomponent polymer melts, G. Wang, Y. Ren, and M. Müller, Macromolecules 52, 7704 (2019)