Synthesis And Application Of Cellulose Grafted Helical Poly(phenyl Isocyanide)s Copolymer

Cellulose is the most abundant,renewable and biodegradable rigid right-handed spiral natural polysaccharide polymer on the earth.Cellulose graft copolymerization is one of the methods of cellulose derivatization.It can comprehensively utilize the heat stability,biocompatibility and the side chain properties of cellulose skeleton to obtain new excellent properties,such as chiral separation,wear resistance,water absorption,antifouling and conductivity.A series of functional materials can be prepared by the natural helix chiral transfer of cellulose main chain to the side chain.In this paper,two click chemistry techniques are used to graft helix poly(phenyl isocyanide)s onto cellulose materials,which would give the copolymer new properties.One is that poly(phenyl isocyanide)s was grafted onto ethyl cellulose to endow the copolymer better chrial recognition.The other is that pentafluorophenol isonitrile was grafted on wood surface to give new properties such as superhydrophobic,self cleaning,wear resistance,chiral adsorption,bacteriostasis,etc.The main contents of the study are as follows:In the second chapter,N₃-2,3-EC was prepared by regioselective method as the main chain of graft copolymer.At the same time,palladium(II)complex with alkyne terminal group was used as initiator to initiate phenylene isonitrile polymerization to prepare helical poly(phenylene isonitrile)(PPI_n)with controllable molecular weight and narrow molecular weight distribution as side chain.A series of copolymers with different grafting sites,degree of substitution and molecular weight were synthesized via“Cu AAC”click chemistry.The results show that the chiral value of the graft copolymer will increase with the increase of the degree of substitution and the molecular weight,and the chiral value of EC_0.81-2,3-g-PPI₅₀is 301.9%higher than that of pure PPI₅₀.EC-2,3-g-PPI₅₀has excellent chiral recognition property,and the absorption of D-type fluorescent probe of alanine methyl ester reaches 99.7%.In third chapter,polypentafluorophenol isonitrile was grafted onto wood surface via"thiol-ene"click chemistry.First,a palladium(II)complex with an alkene terminaled group was designed and synthesized,and initiate the polymerization of pentafluorophenol isonitrile monomer to prepare polypentafluorophenol isonitrile(PFPI_n);At the same time,the cellulose substrate is modified with3-mercaptopropyltrimethoxysilane to obtain the thiolated cellulose substrate;Then a series of materials with polypentafluorophenyl isonitrile grafted onto the surface of cellulose substrates are prepared by click chemistry.The results show that the surface-modified cellulose substrate exhibits super-hydrophobic properties.The water contact angle is between 163°-165°,and the super-hydrophobic-modified material has strong self-cleaning properties against water-soluble pollutants.In addition,it can inhibit the adhesion of S.aureus on the surface of the substrate.This method can be extended to other cellulose products to obtain multifunctional cellulose materials.