Free radical emulsion polymerization of styrene (S) or butyl acrylate (BA) in the presence of latices of linear polythene (PE) prepared by catalytic emulsion polymerization affords colloidally stable multiphase latices. Coagulation of a PE/PS latex affords nanocomposites composed of small PE phases dispersed in a PS matrix, as evidenced by the large supercoolings of PE crystallisation (by DSC). TEM of PE/PBA latices indicates a PBA phase around the PE particles under the emulsion polymerization conditions investigated. Films formed from these dispersions exhibit homogeneously dispersed PE particles.