Tough Al-alginate/poly(N-isopropylacrylamide) hydrogel with tunable LCST for soft robotics
Wen Jiang Zheng1, Ning An, Jian Hai Yang
1School of Science, State Key Laboratory for Mechanical Behaviour of Materials, Collaborative Innovation Center of Suzhou Nano Science and Technology, and ‡State Key Laboratory for Strength and Vibration of Mechanical Structures and School of Aerospace, Xian Jiaotong University , Xi'an 710049, P. R. China.
Abstract:
Tough Al-alginate/poly(N-isopropylacrylamide) (PNIPAM) hydrogel has been synthesized by introducing an interpenetrating network with hybrid physically cross-linked alginate and chemically cross-linked PNIPAM. Varying the concentration of AlCl3 regulates the mechanical properties of the tough hydrogel and tunes its lower critical solution temperature (LCST) as well. The tough Al-alginate/PNIPAM exhibits 6.3 ± 0.3 MPa of compressive stress and 9.95 of uniaxial stretch. Tunability of LCST is also achieved in a wide range within 22.5-32 °C. A bending beam actuator and a four-arm gripper made of bilayer (Na-alginate/PNIPAM)/(Al-alginate/PNIPAM) hydrogel as prototype of all-hydrogel soft robotics are demonstrated. A finite element (FE) simulation model is developed to simulate the deformation of the soft robotics. The FE simulation not only reproduces the deformation process of performed experiments but also predicts more complicated devices that can be explored in the future. This work broadens the application of temperature-responsive PNIPAM-based hydrogels.
