High performance carbon nanotube/polymer composite fibers and water-driven actuators

Abstract Advanced fiber materials made from nanomaterials such as carbon nanotubes (CNTs) have stimulated extensive interest recently; polymer infiltration represents a simple and effective approach to tailor the fiber structure and improve related properties, which deserves more thorough study. Here, we adopted an acid-assisted in situ and scalable polymer infiltration method to prepare continuous CNT/polyvinyl alcohol (PVA) composite fibers, with combined high mechanical strength (up to 2 GPa, and 1.5 GPa at a gauge length of 5 cm) and electrical conductivity (3.16 × 105 S/m), superior than most of previous reports. Based on these, we further fabricated uniformly twisted helical CNT/PVA fibers retaining reasonable strengths (~900 MPa) yet significantly enlarging the tensile strains to as high as 95%. Using the hydrophilicity of infiltrated PVA and the designed helical fiber structure, we created water-driven actuators with axial shrinkage reaching 47% of original fiber length. Our high performance CNT/PVA fibers have potential applications in areas such as multifunctional fiber-based electronics, artificial muscles, smart textiles and soft robotics.