An electroactive actuator includes a polymer electrolyte and an electrode configured to apply an electric field to the polymer electrolyte, the polymer electrolyte includes a self-assembled block copolymer including a conductive block and a non-conductive block, a compound to form a single ion conductor with the self-assembled block copolymer, and a zwitterion. A mechanical device including the electroactive actuator and a polymer electrolyte are also disclosed.