Preparation And Properties Of Functional Bacterial Cellulose Nanocomposites

Bacterial cellulose(BC)has ultra-fine three-dimensional porous fiber structure,high porosity,chemical purity and specific surface area,good mechanical properties and biocompatibility,and there are a large number of active reaction groups on the surface,which provides a favorable chemical environment for modification and surface modification.Therefore,the functional bacterial cellulose nanocomposites based on bacterial cellulose have attracted the attention of researchers.it is widely used in energy storage devices,electromagnetic materials,composite reinforcement,biosensors,medical materials and wastewater treatment and other fields.In the nano-carbon family,graphene is a carbon monolayer with two-dimensional honeycomb lattice structure,which is considered to be the most promising material for supercapacitors because of its large theoretical surface area and high electrical conductivity.However,due to the strong ?-? interaction between graphene sheets,it is easy to agglomerate and stack,which leads to its uneven distribution in electrode materials and poor electrolyte wettability,which seriously limits its application performance in supercapacitors.In order to solve the above problems,the cationized BC(QA-BC)modified by 3-chloro-2-hydroxypropyl trimethyl ammonium chloride(QA)was introduced for the first time to restrain the ?-? interaction between graphene sheets,and the problem of easy stacking and agglomeration between reduced graphene(RGO)layers was solved,and QA-BC/RGO electrode materials with good electrochemical properties were prepared.Nanometer ferric oxide(Fe3O4)is widely used in microwave absorbing materials,biomedicine,magnetic fluid catalysts and other fields because of its small size effect,surface effect,high Curie temperature,good stability,low toxicity and strong biocompatibility.However,due to the van der Waals force and intrinsic magnetic interaction between Fe3O4 particles,it is easy to agglomerate into larger particles,which reduces its specific surface area and dispersion stability,and greatly limits its scope of application.In order to solve the above problems,BC(EDTA-BC)modified by ethylenediamine tetraacetic acid(EDTA)was introduced as the matrix and EDTA-BC/Fe3O4 composites were prepared by in-situ coprecipitation method.the three-dimensional porous fiber structure of the matrix and the coordination between the groups and metal ions are beneficial to the dispersion and stability of Fe3O4 nanoparticles,solve the problem of easy sedimentation and agglomeration of Fe3O4,and improve the stability of EDTA-BC/Fe3O4 suspension.And it is applied to the field of wave-absorbing materials.This paper not only improves the dispersion of graphene and Fe3O4 nanoparticles,but also endows bacterial cellulose matrix composites with good application properties.The specific contents and results are as follows:1.In the part of preparation and properties of bacterial cellulose-graphene composites,QA-BC/RGO and unmodified bacterial cellulose/graphene(BC/RGO)composites were systematically compared and analyzed.The test results show that compared with BC/RGO,the RGO lamellar in QA-BC/RGO has better dispersion,the stacking agglomeration phenomenon is obviously improved,the overall regularity of the composites is enhanced,and the existence of hydrophilic quaternary ammonium salt groups also improves the hydrophilicity of the composites.The electrical conductivity of the composite was significantly improved,the conductivity reached 3.5 S/cm,and the specific capacity of the electrode material increased from 70F/g to 152F/g.2.In the part of preparation and properties of bacterial cellulose-ferric oxide composites,firstly,the effects of iron ion concentration,ripening temperature,ripening time and drying conditions on the structure,morphology and magnetic properties of Fe3O4 nanoparticles were systematically studied by orthogonal experiments and single factor experiments.On the basis of this study,in order to improve the dispersion of Fe3O4 nanoparticles,BC/Fe3O4 composites were prepared by in-situ coprecipitation method.The effects of the introduction of BC and BC concentration on the structure,morphology,dispersion and magnetic properties of BC/Fe3O4 composites were discussed.In order to further improve the dispersion of BC/Fe3O4 composites,EDTA-BC/Fe3O4 composites were prepared by in-situ coprecipitation method.The effects of the introduction of EDTA on the dispersibility,thermal stability and magnetic properties of EDTA-BC/Fe3O4 composites were studied systematically.Finally,the waterborne epoxy resin emulsion(WEP),was prepared by mechanical emulsification,and EDTA-BC/Fe3O4 was used as a magnetic filler to prepare WEP/EDTA-BC/Fe3O4 composites.The effects of the introduction and addition of EDTA-BC/Fe3O4 on the morphology and properties of WEP/EDTA-BC/Fe3O4 composites were investigated,and its application properties in the field of wave absorption were studied.The test results show that the introduction of EDTA-BC significantly improves the dispersion stability of EDTA-BC/Fe3O4 suspension and the magnetic properties of the composites,and the maximum absorption strength of the prepared WEP/EDTA-BC/Fe3O4 composites reaches-12.4dB.