Tunable carbon nanotube ionic polymer actuators that are operable in dry conditions

Actuators are widely used in intelligent material systems. However, electromagnetic, piezoelectric or shape memory alloy actuators are too heavy, complicated and too slow for such applications. In contrast, electroactive polymers (EAPs) are relatively lightweight, rather simple and fast enough to suit the requirements of an actuator. In this study, we have developed CNT ionic polymer actuators that are operable in a wide range of humidities. Optimum performance can be tunable by the addition of different CNT concentrations. A low percentage of CNT will form well distributed sponge-like structures which enable effective entrapment of moisture within the polymer matrix and thus favor the work of the actuator in dry environments, while a higher CNT percentage will lower the water absorption rate, and increase the elastic pressure of the matrix to reduce swelling and deformation. Therefore, the actuators also work well in very high humidity. It is likely that this actuator will have a wide range of bio-inspired applications.