Preparation Of Superhydrophobic Materials And Their Application In Oil-water Separation

Through the study of biological surfaces in nature,people gradually understand the special wettability behavior which attracts people to focus and explore biomimetic superhydrophobic materials continuously.Special wettability surfaces have great application prospects in the fields of oil-water separation,anti-corrosion,anti-icing,anti-fogging,self-cleaning,anti-bacterial,microfluidic and drag reduction.In recent years,special wettability materials have attracted much attention due to their high selectivity and high separation efficiency to application for the oil-water separation.However,the preparation of this kind of materials has the disadvantages of using materials that are not environmentally friendly,lacking durability,complicated processes,and incapable of large-scale production.Moreover,some of the low-surface energy materials used are expensive,which limits the application of superhydrophobic materials.UV curing technology has attracted much attention because of its economy for energy and ecology,but it is seldom used in the preparation of superhydrophobic materials.In this paper,simple process and UV curing method are used to prepare stable superhydrophobic surfaces,and the application in oil-water separation is emphasized.Superhydrophobic materials containing fluorine are prepared by copolymerization and grafting modification of 2-(perfluorohexyl)ethyl methacrylate(FMA)with short fluorocarbon chain,then it is applied to hydrophobic and oleophobic fabric.Special wettability sponges are prepared by simple silicon dip-coated melamine sponge(SM)and photo-induced thoil-ene click reation.The oil-water separation,adsorption and recycling properties of the sponge are studied.A novel photochromic superhydrophobic sponge(PDMS-SP)was prepared by dip-coating and thermocuring.Then the preparation of hydrophobic and oleophylic sponges are applied to the extraction and detection of trace gasoline,kerosene and diesel oil in water.The content of this thesis is divided into four portions:Firstly,FMA with short fluorocarbon chains and glycidyl methacrylate(GMA)is used to synthesize the random copolymers containing epoxy groups FG,ring opening reaction between amino groups of p-aminobenzoic acid(PABA),a new polymer FGN is obtained with hydrophilic carboxylic acid groups in polymer chain.The structure of the prepared FG and FGN are characterized by Fourier transform infrared spectroscopy(FTIR)and nuclear magnetic resonance(NMR)spectroscopy.And then using FGN as macromolecular emulsifier,the core-shell type emulsion FGNF is obtained,particle size analyzer(DLS)to characterize the average particle size of the emulsion is 227.6 nm,and the dispersion coefficient is 0.196.The surface morphology of FG?FGN and FGNF film is characterized by scanning electron microscopy(SEM)and atomic force microscopy(AFM).The surface of FGN film form more pore structure,and the roughness of the FGN surface(Rq=37.1 nm)is significantly larger than FG(Rq=10.5 nm).Effect of adding SiO2 and Al2O3 nano-particles on the surface morphology is discussed.The water contact angles(WCA)of FG?FGN and FGNF film are above 110°,The fluorinated polymer is also applied to the cotton fabric.Under the condition of 10%fluorine resin content and 100?,the WCA is increased to 150.9°,and the contact angle with cetane phase is 102.1°.Secondly,two kinds of photo-induced tholi-ene click reaction systems are selected.One is the small molecule 2,4,6,8-tetravinyl-2,4,6,8-tetramethylcyclotetrasiloxane(TMTVSi)and pentaerythritoltetra(3-mercaptopropionate)(PETMP)as the reactants,and the other is macromolecules of polythiolmethylsiloxane(PDMS-SH)now synthesized and vinyl polysiloxane(PMVS)are prepared by dip-coating and photo-induced thoil-ene click reation of melamine sponge(SM).Special wettability sponge of TMT-SM and PMVS-SM which formed of the silicone coating on the surface of the sponge skeleton are characterized by FTIR,Energy dispersive spectrum(EDS)and X-ray photoelectron spectroscopy(XPS).The morphology of the sponges are characterized by SEM.The influence of the sponge height cured by the ultraviolet,adding nano-silica particles and etching on surface water contact angle is investigated.After adding hydrophobic nano-silica particles,the surface WCA of the prepared sponge can reach 152.3±2.1°,and the WCA of the etched sponge can reach 152.1.9±2.8°.The obtained PMVS-SM sponge has excellent ability to absorp oil,which can reach 49.6?144.0 times of its own weight and can still maintain good performance absorpting oil after hundreds of adsorption/extrusion cycles.Thirdly,a novel photochromic superhydrophobic melamine sponge(PDMS-SP sponge)is fabricated by facilely dip-coating and thermocuring of hydroxyl-terminated polydimethylsiloxanes(HO-PDMS)mixed with photochromic spiropyran(SPMA)and hexadecyltrimethoxysilane(HDTMS).FT-IR,EDS and XPS results confirm the successful coating of PDMS-SP upon melamine sponge.The resultant sponge not only possesses excellent water repellency with a contact angle of 154.5° and oil-water separation efficiency with an oil absorption capacity of 48?116 folds of itself weight,but also shows photochromic phenomenon between colorless and purple when it is successively exposed to UV irradiation and visible light.Fourthly,the special wettability of oil-water separation sponge material prepared in our previous work is used in the extraction and trace analysis of gasoline,kerosene and diesel,in order to solve the difficult problem of extraction and analysis of trace oil ignitable liquids in water.Studied the selectivity of the oil-water mixture by hydrophobic and oleophylic PVMS-SM sponge,and the sponge is connected with the vacuum device to achieve the continuous oil collection phase at the oil-water interface.Then the PVMS-SM sponge is applied to the extraction and analysis of trace ignitable liquids,using sponge combine with liquid-liquid extraction and headspace solid-phase microextraction(HS-SPME)analysis techniques.The results show that the extraction efficiency of PVMS-SM sponge combine is higher than that of ordinary liquid-liquid extraction,and the amount of solvent used can be controlled.In the concentration range of 0.01-0.2?L/mL,the linear relation curve of gasoline,kerosene and diesel oil is established,the correlation coefficient of the curves are above 0.99,and the linear relation is good,the detection limit and quantitative limit of some components in gasoline,kerosene and diesel oil are calculated,a new method is established for the extraction of trace ignitable liquids in water.PVMS-SM combine with HS-SPME analysis ignitable liquids in water with 5 ?L/L is investigated.Compared with the standard of ignitable liquids,the components of toluene and xylene in gasoline can not be detected,diesel oil can not detect all alkanes,and kerosene can detect all the components.The method can be applied to the extraction and detection of trace kerosene in water surface.