Study On Bilayer Hydrogel Soft Actuator With Large Bending Angle And Bidirectional Bending Performance

Compared with rigid robots,soft actuators have the characteristics of intelligence,flexibility and safety,and have great development prospects.Hydrogel can produce volume changes in response to external environmental factors.The bilayer hydrogel structures prepared from two different hydrogel use the difference in volume changes between the hydrogel layers to achieve shape changes,such as bending and twisting.Soft actuators prepared with a bilayer hydrogel structure have been widely used in the fields of drug release,artificial muscles,and bionic soft actuators.However,there are problems,such as slow response speed,small bending deformation range,and single function.Therefore,it is necessary to continuously develop new materials and preparation methods to optimize the performance of the bilayer hydrogel soft actuator.Phenylboronic acid functionalized hydrogel can produce large volume changes in response to pH.In this thesis,based on the poly(acrylamide-acrylic acid)hydrogel grafted with 3-acrylamidophenylboronic acid,two bilayer hydrogel soft actuators with adhesive ability,that can quickly achieve large bidirectional bending behavior are prepared.The main research content is as follows:(1)Based on the poly(acrylamide-acrylic acid)hydrogel grafted with 3-acrylamidophenylboronic acid,poly(3-acrylamidophenylboronic acid-acrylamide-acrylic acid)(P(3-AAPBA)-AAm-AAc))hydrogel with good pH responsive is prepared.Then,P(AAPBAAAm-AAc)hydrogel and polyacrylamide(PAAm)hydrogel are polymerized layer by layer to prepare P(AAPBA-AAm-AAc)/PAAm bilayer hydrogel soft actuator with good pH responsiveness by UV light irradiation.(2)The bending speed and direction of the hydrogel soft actuator can be controlled by adjusting the pH value;the bending speed of the hydrogel soft actuator decreases with the increase of glucose concentration;2.5wt% and 7.5wt% 3-acrylamidophenylboronic acid hydrogel soft actuators can achieve better bending behavior;the presence of acrylic acid greatly promotes the bending behavior of the hydrogel soft actuator.(3)By controlling the actuation conditions of the reversible bending,it is proved that the P(AAPBA-AAm-AAc)/PAAm bilayer hydrogel soft actuator can realize the reversible bending deformation in multiple cycles,and it only takes about 210 s from +360° to-360°.P(AAPBA-AAm-AAc)/PAAm bilayer hydrogel soft actuator with strong adhesion was prepared.Finally,the P(AAPBA-AAm-AAc)/PAAm bilayer hydrogel structure was used to prepare the Drosera-like hydrogel soft actuator,the flower-shaped hydrogel actuator and the hand-shaped hydrogel actuator.(4)Layer-by-layer polymerization of poly(3-acrylamidophenylboronic acid-acrylamideacrylic acid)(P(3-AAPBA-AAm-AAc))hydrogel with good pH responsiveness and good thermal responsive poly-N-isopropylacrylamide(PNIPAM)hydrogel by UV light irradiation,a P(AAPBA-AAm-AAc)/PNIPAM bilayer hydrogel soft actuator with pH-temperature coresponsiveness was prepared.(5)Low temperature and low pH,high temperature and high pH are respectively beneficial to the forward and reverse bending deformation of the soft actuator.The maximum bending angle(～-1400°)can be reached in about 16 minutes in the high temperature and high pH solution.The increase in thickness will reduce the bending rate of the soft actuator.(6)By controlling the actuation conditions of the reversible bending,it is proved that the P(AAPBA-AAm-AAc)/PNIPAM bilayer hydrogel soft actuator can realize reversible bending deformation in multiple cycles,and it only takes about 75 s from +360° to-360°.The P(AAPBA-AAm-AAc)/PNIPAM bilayer hydrogel soft execution device with strong adhesiveness is prepared.Finally,the P(AAPBA-AAm-AAc)/PNIPAM bilayer hydrogel structure was used to prepare a soft hydrogel gripper that could mimic a robotic arm.,a flowershaped hydrogel actuator,and a hand-shaped hydrogel actuator...