Two ternary blend systems of low-density polyethylene/poly(ether-block-amide)/polyethylene terephthalate (LDPE/PEBA/PET) and LDPE/PEBA/polyvinylidene fluoride (PVDF) are prepared by melt blending to thermodynamically assemble the ionically conductive PEBA copolymer at the continuous interface. The LDPE/PEBA/PET blend demonstrates weak partial wetting and a novel morphology transition to complete wetting was observed as the PEBA composition increases from 3% to about 10%. The phenomena can be explained by a mechanism based on the competition between dewetting and coalescence of the PEBA phase at the interface. In the completely wet LDPE/PEBA/PVDF system, a minimum concentration is required to form intact PEBA layers with a thickness of similar to 100 nm. Assembling PEBA at the interface of the ternary systems results in the formation of conductive pathways of very low percolation thresholds and thus leads to a significant reduction in the resistivity for both ternary systems as compared to binary blends with PEBA. A particularly sharp drop in resistivity is observed for the complete wetting morphology of LDPE/PEBA/PVDF.