We introduce a quite simple model for a phase-separating binary mixture where one of the components is cross-linked. It is shown by computer simulations that target patterns are generated. We use a Cahn-Hilliard equation with a bulk free energy density which varies as a molecular weight changes with time. Target patterns are obtained in the following way. We first quench the system, having an off-critical composition, into a spinodal region, and find that disconnected droplets emerge in the system. With cross-linking one of the components, the phase diagram of the system shifts to a location where a bicontinuous structure is formed. As a result, target patterns grow from the droplets without any additional nuclei.
ASJC Scopus subject areas