Study On Preparation And Properties Of PVA-based Composite Hydrogel With High Performance

Polyvinyl alcohol-based(PVA)hydrogel has been favored by researchers because of its ultrahigh water content,low toxicity,easy processing,good chemical stability and biocompatibility,and has widely application prospects in the fields of agriculture,industry and biomedicine.However,PVAbased hydrogel has some problems,such as significantly decreased mechanical properties after swelling,easy break and no self-healing after damage,which limit its application in biomedical and other fields.In this study,polyvinyl alcohol/Agar double-network hydrogel(PVA/AG)was constructed by one-pot method.PVA-based composite hydrogels were also prepared by introductng graphene oxide(GO)with rigid structure and quaternary ammonium salt chitosan(TMC)with antibacterial properties into PVA hydrogels in order to improve the disadvantages of PVA-based hydrogels.The phased research results are as follows:Firstly,PVA/AG hydrogels with double-network interpenetrating structure were prepared by one pot method and freezing / thawing cycle method.And then salt-immersed PVA/AG double-network hydrogels were prepared by treating them with saturated salt water.The effects of AG contents on the chemical structure,mechanical properties,swelling properties,self-healing and low temperature resistance of the hydrogels were investigated through infrared spectroscopy,X-ray diffraction,mechanical extensometer and thermogravimetric analysis.The results show that PVA/AG doublenetwork hydrogel has excellent mechanical properties,and the mechanical properties are obviously enhanced with the increase of AG contents.For example,the tensile strength and compressive strength of PVA-25/AG-3 hydrogel up to 795 k Pa and 2500 k Pa,are 3 and 2 times that of pure PVA hydrogel,respectively.At the same time,the PVA/AG double-network hydrogel based on inverse hydrogen bond has good anti-swelling and self-healing properties,and the self-healing rate is up to 93.4%.In addition,salt immersion treatment can obviously improve the mechanical properties of PVA/AG hydrogel,and the best performance can be obtained by adjusting the salt soaking time.For example,the compressive strength of salt-immersed PVA/AG-24 hydrogels up to 3140 k Pa,is nearly 7 times higher than that of no salt-immersed hydrogels.And salt-immersed PVA/AG hydrogels also have excellent low temperature resistance and anti-swelling properties,which not only maintain an intact appearance but also still have good mechanical properties after being frozen at-23 °C for 24 h.The enhancement of these properties is attributed to the fact that PVA/AG hydrogels are composed of rigid and brittle compact AG networks formed by hydrogen bond and soft and tough loose PVA networks formed by physical cross-linking.Using sulfonated graphene oxide(SGO)as a nano-inorganic substance,PVA/SGO composite hydrogel was prepared on the basis of a nano-reinforcement mechanism.The chemical structure,mechanical properties,swelling properties and self-healing properties of the composite hydrogel were investigated by characterization methods and testing methods such as infrared spectroscopy,X-ray diffraction,mechanical extensometer,and thermogravimetric analysis.The research results show that the PVA/SGO composite hydrogel has excellent mechanical properties,good thermal stability,antiswelling performance,and self-healing performance(self-healing rate up to 83%).The contents of SGO nanoparticle can enhance the comprehensive performance of the composite hrdrogels,in particular obviously improve mechanical performance.Water-soluble cationic quaternized chitosan(TMC)was first synthesized through Schiff base reaction and alkyl halide reaction.Then,PVA/SGO/TMC composite hydrogel was prepared by introducing TMC into PVA-based hydrogel.The mechanical properties,self-healing properties and antibacterial properties against Escherichia coli and Staphylococcus aureus of the composite hydrogels were studied.The results show that the PVA/SGO/TMC composite hydrogels possess good antibacterial effects on both S.aureus and E.coli strains.Under the combined function of hydrogen bond and static electricity,the composite hydrogel has good mechanical properties and excellent selfhealing properties(self-healing rate up to 93%).