Characteristics of chemo-mechanically driven polyacrylonitrile fiber gel actuators

Pure polyacrylonitrile (PAN) fiber gels, exhibiting effective actuation forces and displacements through muscle-like contractile behavior during the volume change when subjected to environmental stimuli, are prepared by electrospinning, twisting (strand creation) and activation process to investigate performance characteristics of chemo-mechanically driven PAN gel actuators. Single PAN strand (yarn) having a dimension of 210 μm in diameter is used. A typical hysteresis loop is observed for the length change (∼ 38%) of PAN gels with respect to pH variation. Diameter and volume changes are observed as greater than 100% and greater than 720%, respectively, for pH activated systems. Chemically induced force generation of pure PAN fiber gel is completed within a few seconds. The average maximum force is 0.002 N, implying that the force generation of a single PAN filament is 6.7 × 10− 6 N. A linear relation between force and strain is observed. It is found that PAN fiber gels in contracted state have stronger force and strain (0.043 N/0.112) than those (0.015 N/0.002) in elongated state. The actuation stress of pure PAN is in the range of moving coil transducer and commercial PAN but the actuation strain is better than moving coil transducer and similar to natural muscle.