Pingwen Zhang

Nucleation and Boundary Layer in Diblock Copolymer SCFT Model

The phase diagram of the equilibrium states and the stability of the possible microstructures are both important for polymer scientists. The phase behavior of a diblock copolymer system could be studied through self-consistent mean field theory (SCFT). We extensively study the boundary layer of a diblock copolymer melt confined system using compressible self-consistent mean-field theory. We discover the boundary layer profile and its thickness are only determined by boundary potential and compressible parameter. We have also investigated several effects due to the confinement of polymer melts by impenetrable hard surfaces in the self-consistent field calculations.

We will also introduce a numerical method to study the nucleation in copolymer melts. Nucleation is the decay of a metastable state via the thermally activated formation and subsequent growth of droplets of the equilibrium phase. We will consider the nucleation in diblock copolymer melts, whose equilibrium phases are well understood. We apply a new numerical method, called the string method, to compute the minimum energy path (MEP). Then from the MEP, we find the size and shape of the critical droplet and the free-energy barrier to nucleation.