Diffuse Polymer Interfaces in Lobed Nanoemulsions Preserved in Aqueous Media

Using valence electron energy loss spectroscopy (EELS) in the cryo-scanning transmission electron microscopy (STEM), we found that the polymer−polymer interface in two-phase nanocolloids of polydimethyl siloxane (PDMS) and copolymer (methyl acrylate (MA)−methyl methacrylate (MMA)−vinyl acetate (VA)) preserved in water was diffuse despite the fact that equilibrium thermodynamics indicates it should only be on the order of a few nanometers. The diffuse interface is a result of the kinetic trapping of the copolymer within the PDMS phase, and this finding suggests new nonequilibrium pathways to control interfaces during the synthesis of multicomponent polymeric nanostructures.