Preparation of core–shell coagulates by hydrophobic heterocoagulation of micron-sized poly(methyl methacrylate) and submicron-sized poly(styrene) particles

Core–shell coagulates were prepared by hydrophobic heterocoagulation between non-charged poly(methyl methacrylate) (PMMA) core and cationically charged polystyrene (PSt) shell particles. Addition of NaCl and elevation of coagulation temperature to the vicinity of the glass transition temperature (Tg) of the shell particles are found to be keys to successful heterocoagulation. Fluorescence resonance energy transfer (FRET) experiments using pyrene-labeled core and naphthalene-labeled shell particles showed that interdiffusion of the polymer chains at the interface between the core and shell particles is most effective when coagulates were prepared at or slightly above the Tgs of both core and shell particles.