Skeletal Muscle Fibers Inspired Polymeric Actuator by Assembly of Triblock Polymers

Abstract

Abstract Inspired by the striated structure of skeletal muscle fibers, a polymeric actuator by assembling two symmetric triblock copolymers, namely, polystyrene‐b‐poly(acrylic acid)‐b‐polystyrene (SAS) and polystyrene‐b‐poly(ethylene oxide)‐b‐polystyrene (SES) is developed. Owing to the microphase separation of the triblock copolymers and hydrogen‐bonding complexation of their middle segments, the SAS/SES assembly forms a lamellar structure with alternating vitrified S and hydrogen‐bonded A/E association layers. The SAS/SES strip can be actuated and operate in response to environmental pH. The contraction ratio and working density of the SAS/SES actuator are approximately 50% and 90 kJ m−3, respectively; these values are higher than those of skeletal muscle fibers. In addition, the SAS/SES actuator shows a “catch‐state”, that is, it can maintain force without energy consumption, which is a feature of mollusc muscle but not skeletal muscle. This study provides a biomimetic approach for the development of artificial polymeric actuators with outstanding performance.

Keywords

• actuation
• hydrogen‐bonding complexation
• microphase separation
• pH responsive
• triblock copolymers