Design,Preparation And Characterization Of Fluoro-Functionalized Hydrophobic Materials

Nowadays,mesoporous materials are widely used in the fields of catalysis and adsorption because of their good thermal stability and large specific surface area.Among the more typical mesoporous materials are mesoporous silica and mesoporous alumina,which show great potential in the field of catalysis due to their unique pore structures.However,the presence of a large number of hydroxyl groups on their surfaces makes them hydrophilic.Therefore,mesoporous silica and alumina have not been well developed in the field of oil-water separation.Meanwhile,nanocellulose,as a renewable material,has received much attention due to its biodegradability.In traditional research,nanocellulose is often widely used as a kind of polymer in the preparation of emulsions and flexible electronic sensors.In contrast,it is affected by the large number of hydroxyl and carboxyl groups on its surface,and is rarely applied in hydrophobic and anti-fouling fields.In this thesis,we transform the surface of the originally hydrophilic mesoporous material and cellulose from hydrophilic to hydrophobic by modification.This expands a new platform for its application in the field of oil-water separation and anti-fouling and anti-bacterial.(1)The hydrophobic mesoporous silica(MS)was developed through the surface grafting of the perfluoroalkyl group using the fluorinated organosilane(1H,1H,2H,2H-Perfluorodecyltriethoxysilane).Specifically,the corresponding structure,surface areas,pore-volume,and thermal properties of hydrophobic MS samples were characterized.After the surface grafting,the structure of fluorinated MS remained unchanged.However,the specific surface area decreased from 808 m~2/g to390 m~2/g,and its pore size reduced from 6.2 nm to 4.3 nm.With the increase of fluorosilane content,the MS samples were gradually converted from an initial hydrophilic surface to a superhydrophobic surface with a contact angle up to 156.50°.Moreover,a typical"hills and valleys"surface type for the fluorinated MS was observed due to the obvious surface particle attachment.In the oil-water mixture and the water-in-oil emulsion separation,the separation efficiency was greatly high(>99%)with great stability.Therefore,the fluorinated MS would be expected to provide a potential solution for oil-water remediations.(2)The fluorinated alumina material with a superhydrophobic surface was prepared by grafting 1H,1H,2H,2H-perfluorodecyltriethoxysilane on the mesoporous alumina surface.The water contact angle of aluminum oxide reached as high as163.00°.As compared with mesoporous alumina,the specific surface area of fluorinated alumina was much smaller,dropping from 136 m~2/g to 44 m~2/g.Meanwhile,fluorinated alumina had a large surface roughness(Rq=35.7 nm).Interestingly,with the increase of the amount of fluorinated silane in the grafting reaction,the water contact angle of fluorinated alumina initially increased and then decreased.The high flux(6.084×10~6L/m~2·h·pa)and great separation efficiency(>99%)was obtained with great repeatability during the in oil-water separation.Even this fluorinated alumina can efficiently separate the water-in-oil emulsions.Therefore,this work opens a new platform for the application of superhydrophobic mesoporous alumina in oil-water separation.(3)A fluorinated cellulose material with amphiphobic and antibacterial properties was prepared by grafting perfluorooctanoyl chloride onto the cellulose surface.Specifically,SEM results showed that many nanoparticles appeared on the surface of fluorinated cellulose,which increased the surface roughness of fluorinated cellulose.As compared with the hydrophilic and lipophilic cellulose,the water contact angle of the fluorine-functionalized cellulose was as high as 100.2°and the oil contact angle was as high as 113.1°.At the same time,fluorinated cellulose had a great bacteriostatic effect on Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus).Typically,fluorinated cellulose can effectively reduce the number of bacteria by 1.2orders of magnitude,and the antibacterial efficiency was as high as 93%.Therefore,we expect that fluorine-functionalized cellulose would have great potential in water-repellent,oil-repellent,and antibacterial applications.