Preparation And Performance Research Of Cellulose-based And Nanomaterial

With the wide use of non-biodegradable polymer materials,plastic and microplastic particles pollution in land and aquatic ecosystems have been obtained much attention recently,which has been one of most challenges in terms of sustainable development of human society.It is well recognized that the use of natural polymers as raw sources to prepare materials can significantly contribute the sustainable development of polymer industry,as natural polymers are biodegradable,abundant,low cost,biorenewable.Among of them,cellulose is concerned mostly as it is the most abundant natural polymer resource on earth;furthermore,it also has fascinating properties.In contrast to commonly used thermoplastics,cellulose cannot be melted without structural disintegration and is insoluble in most common solvents.Therefore,the current treatment method not only pollutes the environment but also is a waste of cellulose resources.However,to develop value-added use of cellulose,a first challenge that we meet is to dissolve cellulose facilely.Significant progress has been achieved in terms of green solvents toward a sustainable chemical industry in the preparation of renewable materials and the preparation and functionalization of cellulose nanocrystals.This research based on a structural reconstruction strategy of new cellulose-based materials,which from the perspective of one-dimension,two-dimension and three-dimension structure.The functional materials with different structures were prepared and the properties was studied.（1）:Levulinic acid-derived protic ionic liquids（PILs）were identified to be good solvents for cellulose dissolution and the simultaneous dissolution of wool keratin and cellulose,implying a green dissolution processing platform for regenerated materials preparation derived from both cellulose and keratin.The values of overlap concentration（C*）were identified to be 0.83 wt%,1.3 wt%and 2.01 wt%,in the cases of cellulose,cellulose/wool keratin（5/5）,and pure wool keratin,respectively.Furthermore,cellulose/wool keratin composite membrane was facile cast through sol-gel transition when ethanol was used as coagulation bath,and the membranes were systematically characterized by XRD,FTIR,TGA,as well as SEM.The composite membranes had satisfactory mechanical properties of tensile strength of up to 60 MPa and an elongation at a break of up to 6%.In addition,the composited membranes also have outstanding oxygen barrier performance and satisfactory thermostability.（2）:In this study,a new cellulose/wool keratin composite hydrogel was firstly prepared by one pot reaction in[DBNH][Lev]ionic liquid solvent system.And then,Au nanoparticles C50W50@Au composites were fabricated by the reduction of the absorbed Au（Ⅲ）ions on C50W50 using Na BH₄ as reducing agent.The catalysts were systematically characterized by XRD,FTIR,TEM,and ICP-OES.It was identified that the C50W50 presented good immobilization capacity of Au NPs,and the achieved C50W50@Au composite had high catalytic activity and ex-cellent reusability for the reduction of 4-nitrophenol in water.The activation parameters of the reduction reaction of 4-nitrophenol catalyzed by C50W50@Au were calculated as E_a=20.14 KJ mol^-1,ΔH^#=22.7 k J mol^-1 andΔS^#=-246.0 J mol^-1K^-1.（3）:Cellulose nanocrystal（CNC）was prepared from completely recyclable acidic ionic liquid betaine hydrochloride,and the yield and product performance were further improved by H₂SO₄ or microwave combination.The crystalline structure of CNC remained cellulose I_β,and the crystallinity is increased to 81.3%.AFM and TEM analysis indicated that a typical needle-like nanoparticles with an average length of 155nm of CNC;The esterification reaction between betaine hydrochloride and hydroxyl groups on cellulose makes a certain amount of quaternary ammonium salt structure introduced into cellulose.It has a certain antibacterial effect on Escherichia coli and Staphylococcus aureus.Functional nanocrystalline materials can be prepared by using a certain number of quaternary ammonium salt structures on cellulose groups.