[6] Systematic construction of the dynamic density functional theory for inhomogeneous polymer systems

Time scales predicted by the dynamic density functional theory (DDFT) for an inhomogeneous polymer system are far from accurate. One of the main reasons for this is, approximate local and non-local schemes employed to compute the mobility coefficient,Λαβ(r,r’) . In the DDFT calculations,Λαβ(r,r’), relates the thermodynamic driving force due to the monomer β at r’ to the current of the monomer α at r . In this talk, we will put forward a physically motivated approach to compute the Λαβ(r,r’) with the objective to improve the DDFT predictions. We compute the Λαβ(r,r’) from the relaxation time of the single chain dynamic structure factor. We find that the Λαβ(r,r’) obtained from such an approach captures both the global dynamics and the effective local rearrangements of the chain at relevant length scales. Using this scheme, we conduct DDFT calculations to study two related problems. One is the formation of the lamellar morphology in a symmetric diblock copolymer system starting from a homogeneously dispersed state, and the other is the relaxation of the lamellar morphology into a homogeneously dispersed state. We show that the DDFT predictions for the above problems are in reasonably good agreement with the corresponding fine-grained simulations.