•The combination of PDADMAC and TC4 enable microencapsulation of dodecane in PMMA.•Stabilization of the dodecane–PMMA interface leads to multicore morphology.•PDADMAC adsorbs strongly at the TC4 containing PMMA interface. Multicore–shell particles consisting of a poly(methyl methacrylate) shell and multiple dodecane cores have been prepared via the internal phase separation method using the oil-soluble anionic surfactant sodium 1,5-dioxo-1,5-bis(3,5,5-trimethylhexylocy)-3-((3,5,5 trimethylhexyloxy)carbonyl)pentane-2-sulfonate (TC4) and the water-soluble polycation poly(diallyldimethylammonium chloride) (PDADMAC) in combination as a dispersant pair. The multicore–shell particles have been investigated using SEM, light microscopy and microelectrophoresis. The detailed influence of TC4 on the oil–water, water–polymer and oil–polymer interfaces and its interaction with PDADMAC have been investigated using a quartz crystal microbalance with dissipation monitoring (QCM-D) and different optical tensiometry methods. TC4 stabilizes in particular the polymer–water interface in the presence of PDADMAC instead of the oil–water interface in contrast to water-soluble surfactants. In addition, the oil–polymer interface is stabilized by TC4 which prevents coalescence of the oil droplets and leads to multicore–shell morphology rather than single core–shell.