Preparation And Application Of Composite Hydrogels Based On Exfoliated Mica

Nanocomposites can integrate the characteristics of a single material to obtain better comprehensive properties.Mica,a typical layered silicate mineral containing many sub-species with different properties,has many advantages,including large reserves,low price,exceptional biological safety and environmental compatibility.It is of great economic and practical significance to exfoliate mica into two-dimensional nano-sheets by simple method,which can be used to construct composite materials with better comprehensive properties.Starting from the principle of simplicity and safety,uniform dispersed biotite nanosheets were successfully prepared by sodium modification in large quantities.The biotite nanosheets were then used as photothermal materials to assemble solar water evaporation devices with hydrogel matrix.The exfoliation of biotite powder into nanosheets is simple and can be easily enlarged.The two-dimensional structure of biotite nanosheets helps to increase the crosslinking strength of hydrogel polymer networks,thus enhance the overall mechanical properties of hydrogels.Combined with the effect of hydrogel polymer network on reducing the enthalpy of water evaporation,the composite hydrogel exhibited a high rate solar evaporation rate,reaching 2.0 kg m^-2 H^-1,which was significantly higher than that of composite hydrogel with exfoliated biotite powder as photo thermal material.In addition,magnetic sericite nanosheets were prepared by loading Fe₃O₄nanoparticles onto exfoliated sericite nanosheets by in-situ growth method.In this method,two-dimensional sericite nanosheets were used as supports,and the synthesized Fe₃O₄ nanoparticles with a diameter of less than 10 nm were quite small in size.The combination of Sericite nanosheets and Fe₃O₄nanoparticles can not only prevent the agglomeration of Fe₃O₄ nanoparticles in the reaction process,but also reduce the accumulation of Sericite nanosheets.At the same time,Fe₃O₄ nanoparticles can catalyze a small amount of H₂O₂ in aqueous solution to generate a large number of reactive oxygen species,which can play a role in killing harmful microorganisms.Sericite nanosheets and Fe₃O₄ nanoparticles are all safe and non-toxic.The magnetic two dimensional materials are combined with biosafety NDP hydrogels to form magnetic composite hydrogels.The magnetic and thermal properties and catalytic activities of the magnetic sericite nanosheets complement each other,it is expected toprepare antibacterial materials with better biocompatibility and environmental compatibility.