Preparation And Properties Of High-Strength,Self-healing Double Network Hydrogel

Due to the good hydrophilicity and biocompatibility,hydrogels have been favored by researchers since their first synthesis,and have been widely used in the fields of wound repair,drug control release,biological tissue engineering,device design and so on.However,with the continuous study of the hydrogel material,its disadvantages are gradually exposed.It is found that although hydrogels are similar to biological soft tissues in terms of structure and properties,they are quite different in mechanical properties:conventional hydrogels are soft and fragile,and the mechanical strength is poor,But the soft tissues such as cartilage,tendon have good mechanical properties,can withstand a certain load and have good fatigue resistance.In addition,good self-healing ability is also the key to the application of hydrogels in the field of biological soft tissue.Therefore,the study of high-strength and self-healing hydrogels has profound significance.In this paper,hybrid double network hydrogels and fully physical crosslinked double network hydrogels were prepared based on the concept of double network hydrogel.The specific research contents are as follows:1.A hybrid cross-linked DN hydrogel composed of the first network of PAMAAc-Fe³⁺and the second network of PVA was prepared by a simple"one-pot"method.ATR-FTIR spectra and XRD patterns were used to characterize the formation of Fe³⁺coordination bonds and PVA microcrystalline regions in hydrogel,respectively.Tensile tests and consecutive loading-unloading cycle tests explored the mechanical strength,self-recovery properties and fatigue resistance of the hydrogel.The effects of the content of acrylic acid,the number of freezing/thawing cycles and the concentration of iron ion on the mechanical properties of the hydrogel were also discussed.In addition,the hydrogel also showed certain healing performance by the heating-freezing/thawing process and its healing mechanism was discussed.2.A fully physical crosslinked polyacrylic acid/xanthan gum?PAAc/XG?double network hydrogel was synthesized by an easy“one-pot”free radical polymerization,in which the Ca²⁺cross-linked xanthan gum forms the first network and the hydrophobically modified polyacrylic acid acts as the second network.The effect of different xanthan gum content on the mechanical properties of the hydrogel was investigated,as well as its toughness,fatigue resistance and self-healing properties.Simultaneously,a bilayer actuator with pH response was prepared based on the good self-healing properties,different elastic moduli and different swelling differences in different pH buffer solutions between PAAc/XG hydrogel and PAAc hydrogel,and then its actuating behavior in different pH buffer solutions was explored.