Conjugated polymer composite artificial muscle with solvent-induced anisotropic mechanical actuation

Responsive polymers have been widely studied as actuators in response to external stimuli and exhibit promising applications in wide variety of fields. However, the actuating direction of most polymers cannot be precisely controlled, and the generated low stress and poor stability cannot meet practical applications either. Herein, conjugated polymer/aligned multi-walled carbon nanotube (MWCNT) composites are designed, which can undergo anisotropic and reversible bending/unbending actuations driven by solvents. The actuating direction was accurately controlled to be perpendicular to the MWCNT length, which is realized through the orientation of conjugated polymers induced by aligned MWCNTs. The actuation generates a stress of 15 MPa, approximately 42 times of the strongest human muscle, and the reversible actuations are repeated for 300 cycles without fatigue. These composite artificial muscles can be widely used in numerous fields, such as sensors and actuators.