4D printing technology is advantageous for developing new shape memory effects and new functionalities. Herein, a new kind of photo-thermal staged-responsive shape memory polymers (SMP) were prepared by fused granular fabrication (FGF) 4D printing technology. The integration of azobenzene-containing oligomer with the commercialized thermal-responsive SMP pellets resulted in PEC-Bisdi with good compatibility and higher thermal stability, suitable for FGF 4D printing. The pellets made from the composite can also be used directly in the FGF printing technology. The resulting FGF-printed SME specimens illustrated excellent photo-thermal staged responses with UV-responsive bending, thermal-responsive shape recovery, and good fixation at room temperature. The FGF-printed specimens also displayed good mechanical properties with up to 380% elongation at break and 1.5GPa glassy storage modulus. The influences of material factors and printing parameters were systematically investigated and the results showed an increase in the curvature of the spline as a function of Bisdi content and elongation, while a decrease was recorded as a function of the spline thickness. The optimal printing parameters for the highest curvature were determined as 140 extrusion rate, 230℃ extrusion temperature, 80 routing rate, and parallel infill pattern. Overall, the proposed PEC-Bisdi composites showing programmable and remotely controllable shape memory capabilities have the potential for use in advanced engineering and soft robotics.
Yuxia Jin,Qing Zhu,Weibing Zhong,Kelu Yan,Dong Wang
Despite much progress in solvent-sensitive actuators, most of the actuators are sensitive to water, ethanol, or acetone with low responsive speed and small curvature. Herein, a simple approach was introduced to fabricate a new solvent-sensitive bilayer actuator consisting of a poly(vinyl alcohol-co-ethylene) (EVOH) nanofibrous membrane and polystyrene (PS) microspheres. The actuator showed superfast and multistimulus responsive ability to organic vapors of toluene, chloroform, THF, and acetone. With solvents stimulation, the difference in swelling degree between the EVOH layer and PS microspheres layer contributed to the asymmetric expansions or contractions of two layers, therefore resulting in the mechanical deformation of the actuator. The flexible and porous EVOH nanofibrous membrane, as well as the spherical PS, could improve the response rate and deformation scale. This bilayer actuator could bend quickly into a multicoil with the curvature of 21.02 cm–1 within 0.15 s in response to toluene vapor, and the bending–unbending process could repeat more than 150 times when the deformation degree was controlled by cross-linking PS microspheres with divinylbenzene. This study will provide an important insight for the development of new solvent-sensitive devices and applications in volatile organic compounds detecting.
危险品化学品经营许可证（带存储）