Preparation And Structure And Property Investigation Of Multiple Stimulus-response Intelligent Hydrogels

Compared with traditional hydrogels,intelligent hydrogels can response to external stimuli spontaneously and have attracted more and more attention.shape memory hydrogels and self-driving hydrogels are the main intelligent hydrogels.However,shape memory hydrogels are confronted with certain challenges for the biomedical applications,such as the the poor mechanical properties and unsafe response process which may limit the applications in biomedical area.The self-deforming hydrogel emerges as the times require because it is impossible to fix the temporary of shape memory hydrogels in the harsh environment.Based on this,we have carried out the following two aspects of research: 1.Preparation and property investigation of near infrared activated 3D printing high strength double network shape memory hydrogels.Shape memory hydrogel has attracted more and more attention because of its unique excellent performance.However,a great deal of factors has limited the development of shape memory hydrogels,such as poor mechanical properties,unsafe recovery temperature and simple internal and external structures.And in this work,we expect to design a kind of double network shape memory hydrogels activated by near infrared with excellent performances.Near-infrared(NIR)-responsive double network shape memory hydrogels were formed by chemically cross-linking Pluronic F127 diacrylate macromer(F127DA)and physical blending of poly(lactide-co-glycolide)(PLGA)with graphene oxide(GO),and were manufactured with 3D-printing technology using ultraviolet light polymerization.The morphologies and crystalline structure of the hydrogels were determined by scanning electron microscopy(SEM)and X-ray diffraction(XRD).The NIR and thermal activated shape memory properties,mechanical toughness,and cytotoxicity were investigated.The shape memory properties were improved by incorporating GO into the hydrogels and the mechanical properties were enhanced by the addition of PLGA,which served as a second network.The cytotoxicity was assessed by the CCK-8 assay,which revealed no cytotoxicity.The nontoxicity,high mechanical toughness(3.45 MPa in the swollen state),and biosafety at the shape recovery temperature(36 ± 1°C),which was achieved by NIR stimuli,indicates that shape memory hydrogels can be used in biomedical materials safely.Our results propose that F127DA/PLGA/GO hydrogels will be a promising material in biomedical applications as a drug carrier and an antibacterial scaffold.2.Preparation and property investigation of metal ions and temperature dual stimuli-response hydrogel actuators.Hydrogel actuators emerge as the times require due to it is difficult to fix temporary shape of shape memory hydrogels in complex environments.In this study,NIPAM hydrogel was prepared by thermal crosslinking,and AAm/AAc hydrogel was prepared by photocrosslinking,then bilayer hydrogel actuators were formed.The swelling behavior of bilayer hydrogel and monolayer hydrogel in metal ion solution was investigated.The swelling rate of the AAm/AAc and NIPAM hydrogel in the metal ion solution is different and stress is generated inside the hydrogel,resulting in different bending directions.The NIPAM layer hydrogel,as a thermo-sensitive hydrogel,occurred deswelling behavior;while the AAm/AAc layer hydrogel did not change significantly at the time of heating,so the hydrogel actuator bent to NIPAM layer.In addition,mechanical properties tests indicate that the mechanical properties of the hydrogel meet the requirements of the actuator.The research of the hydrogel actuator opens up the field for the use of NIPAM hydrogel,and also provides a new idea for the future research of the hydrogel actuator.