Multiscale Simulations of Triblock Copolymers

Triblock copolymers self-assemble into a rich spectrum of microphase separated morphologies such as lamellae and cylinders. These materials are utilized in numerous materials science applications such as in membranes for protective clothing, fuel cells, and batteries. Such mesoscale features of copolymers extend to hundreds of nanometers and form in microseconds or longer times. However, many interesting processes, such as diffusion, occur within these mesoscale phases much faster and depend on underlying atomistic structure of the polymer. Such structure, in turn, is a function of molecular interactions at the fundamental quantum level. Thus comprehensive simulations of copolymers require consideration of quantum, atomistic, and mesoscale phenomena, spanning vastly different time and length scales. These simulations can be accomplished through sequential multiscale modeling. In this article, we describe key concepts and discuss interdependence and accuracy at various stages of this multiscale approach. Results are presented for a poly (styrene-b-isobutylene-b-styrene) copolymer that, in its sulfonated form, was found to be useful as a membrane in protective garments.