This paper describes new electroelastomer films that exhibit high actuation performance at zero to minimal mechanical prestrain. Prestrain is generally required for electroelastomers, also known as dielectric elastomers, such as the VHB 4910 acrylic elastomer, to obtain high electromechanical strain and high elastic energy density. However, the prestrain can cause several serious problems, including the use of a prestrain-supporting structure, a large performance gap between the active materials and packaged actuators, instability at interfaces between the elastomer and prestrain-supporting structure, and stress relaxation. We have introduced a polymerizable and closslinkable liquid additive into highly prestrained acrylic films and subsequently cured the additive to form the second elastomeric network. In the as-obtained Interpenetrating Polymer Networks (IPN), the additive network can effectively support the prestrain of the acrylic films and consequently eliminate the external prestrain- supporting structure. The IPN composite films without external prestrain exhibit electrically-induced strains up to 233% in area, comparable to the VHB 4910 films under high prestrain.