NIR–vis–UV Light‐Responsive High Stress‐Generating Polymer Actuators with a Reduced Creep Rate

Abstract

Untethered, light-responsive, high-stress-generating actuators based on widely-used commercial polymers are appealing for applications in soft robotics. However, the construction of actuators that are stable and reversibly responsive to low-intensity ultraviolet, visible, and infrared lights remains challenging. Here, transparent, stress-generating actuators are reported based on ultradrawn, ultrahigh molecular weight polyethylene films. The composite films have different draw ratios (30, 70, and 100) and contain a small amount of graphene in combination with ultraviolet and near-infrared-absorbing dyes. The composite actuators respond rapidly (t 0.9 < 0.8 s) to different wavelengths of light (i.e., 780, 455, and 365 nm). A maximum photoinduced stress of 35 MPa is achieved at a draw ratio of 70 under near-infrared light irradiation. The photoinduced stress increases linearly with the light intensity, indicating the transfer of light into thermally induced mechanical contraction. Moreover, the addition of additives lead to a reduction in the plastic creep rate of the drawn films compared to their nonmodified counterparts.

A pH-Responsive Liquid Crystal Hydrogel Actuator with Calcium-Induced Reprogrammable Shape Fixing

“…Functionalized anisotropic polyolefins were used to fabricate soft actuators by either incorporation of responsive small organic molecules or a secondary responsive polymer network. Light-, − humidity-, and temperature-responsive anisotropic polyolefin actuators have been reported. ,,, Expanding the types of stimuli and enabling shape reprogramming of the actuators may increase the range of applications for these types of soft polymer actuators.…”