The insulating materials used to develop HVDC technologies suffer from a major drawback, which is the accumulation of electrical charges forming internal space charge with possibly two major consequences: (i)-the out-of-control of the internal electric field distribution initiating current runaway and (ii)-cumulated molecular level damages extending or creating defects and leading ultimately to breakdown. To prevent space charge accumulation, one possible route, not examined in depth by the scientific community to date is to control the charge injection at the interfaces between the insulating material and the "electrodes" (metallic or semi-conducting). Different routes were followed in this work for tailoring the interface between electrode and polyethylene material, based on chemical modification of the insulation or layer intercalation. Depending on the process, charge injection control is achieved either for negative charges or for charges of both polarities. The process of charge injection control is discussed with reference to the chemical/physical modifications brought about by the different treatments. The results provide indication towards a strategy to control the injection in power cables and other electrical components.