Study On 3D Printing And Intelligent Deformation Of Physical Crosslinked Double Network Hydrogel With High Strength

Intelligent deformation hydrogel is a kind of intelligent material that can sense external stimuli and actively respond to external environment?temperature,solution,light,etc.?to change its shape.This environmental responsiveness has broad application prospects in the fields of biomedicine and smart devices.In recent years,researchers have achieved a variety of intelligent deformation by preparing a thickness or plane gradient hydrogel by combination method and photolithography.However,the direction of bending deformation caused by the thickness gradient prepared by the combination method is specific;and the planar gradient structure prepared by photolithography involves two kinds of hydrogel composite polymerization,the polymerization process is complicated,and the mechanical properties are generally poor.In view of the above problems,this paper designs the molecular structure,preferably the carboxyl-rich polymer as the raw material,so that the hydrogel has excellent mechanical properties and is easy to 3D molding.Firstly,the template cross-linking method is proposed to make the same hydrogel reasonable.Regional cross-linking results in a patterned planar gradient structured hydrogel that,under environmental stimuli,produces internal stresses due to regional swelling differences that drive the hydrogel to deform.And the3D printing technology is used to prepare a fine complex gradient structure hydrogel,and the 4D printing material is realized by environmental stimulation.?1?SA/P?AAm-co-AAc?hydrogel was prepared by using natural polymer sodium alginate?SA?as a heavy network and a copolymer of acrylamide?AAm?and acrylic acid?AAc?as a heavy network.The Fe³⁺solution was soaked to obtain an ion double crosslinked SA/P?AAm-co-AAc?/Fe³⁺hydrogel.The hydrogel has a water content of76%and maintains 1228%strain while the stress is as high as 3.24 MPa.The enhancement mechanism was studied and confirmed.The weak SA/Fe³⁺network plays a toughening effect,and the strong P?AAm-co-AAc?/Fe³⁺network enhances.The hydrogel has shape memory by ionic cross-linking under acidic conditions and neutral under-reconstruction.In addition,the template cross-linking method was first proposed to partially crosslink the SA/P?AAm-co-AAc?hydrogel,and the planar gradient structure was obtained to realize the intelligent deformation of the hydrogel.?2?A sodium alginate/polyvinyl alcohol?SA/PVA?hydrogel was prepared using a natural polymer as a raw material.Gradient structure hydrogels were constructed by template cross-linking method with parallel stripe and dome as the base deformation unit.A specific variety of configurations are obtained by pre-swelling the direction of swelling that induces swelling.The template cross-linking method can also realize the deformation of a multi-unit complex structure such as flower opening,finger bending and the like.In addition,3D printed PVA and SA/PVA composite hydrogels,the SA/PVA hydrogel layer swells in water and shrinks in the salt solution,the composite hydrogel undergoes reversible curl deformation,changing the printing path to control the bending direction,A variety of different configurations are obtained.In this study,through molecular structure design,the template cross-linking method was first proposed to construct a planar gradient structure hydrogel,which realized the intelligent deformation of high mechanical properties hydrogel.The enhancement principle of hydrogel was analyzed,and the principle and influencing factors of deformation were revealed.A two-layer composite hydrogel was prepared by3D printing technology,demonstrating a method of adjusting the deformation of the printing route.The above methods have wide applicability and have opened up a new path for the application of intelligent deformation hydrogels.