An In Siu Polymerization Approach For The Synthesis Of Superhydrophobic And Superoleophilic Nanofibrous Memberanes For Oil-Water Separation

The wettability is an important properties for solid surface, inspired by the superhydrophbobic phenomena in nature, reseachers have paid great attentions to the design, fabrication and character investigation of the superhydrophobic materials. Contact angle in solid surface is commonly used to characterize the wetting properties, for water or oil, smaller than5°is called superhydrophilic or superoleophilic, greater than150°is called superhydrophobic or superoleophobic. Furthermore, the contact angle in solid surface, which is greater than150°for water and smaller than5°for oil, is called superhydrophobic and superhydrophilic. The materials with superhydrophobic surface have bright futrue for various applications in clothing, building, medical, automobile, communication, etc. And for the materials with superhydrophobic and superhydrophilic surface, which have great application in industrial oil-polluted water treatments and oil spill cleanup, because of the fast and efficient separation for oil/water mixtures by the interfacial phenomenon. Conventionally, there are two approaches to produce the superhydrophobic surfaces:One is to modify the surface with low surface free energy material on the rough surface, the other is to creat rough surface on the low surface free energy surface.In this paper, inspired by the superhydrophobic phenomenon of lotus leaf and sliver ragwort leaf. First, we prepare the cellulose acetate (CA) nanofibers by the electrospinning, and then the BAF-tfa monomer of fluorinated polybenzoxazine (F-PBZ) through the solvent-free synthesis method, which has low surface free energy, and by the situ polymerization of the BAF-tfa monomer, forming F-PBZ functional layer on the surface of the CA nanofibers and getting F-PBZ/CA membrane with low surface free energy. Finally modified the surface of F-PBZ/CA membrance by the SiO2nanoparticles (SiO2NPs), we get F-PBZ/CA/SiO2function membrane with superhydrophobic and superoleophilic, which has the imitation structure of lotus leaf and silver ragwort leaf. The CA nanofiber exhibite a silver-leaf-like structure with mico-scaled bumps on the fibers surfaces due to the rapid phase separation in electrospinning and calcinations processing. And then the CA nanofiber surface is modified by the BAF-tfa monomer and SiO2nanoparticles, the content of BAF-tfa monomer and SiO2nanoparticles proved to be the key factor affecting the fiber surface free energy and roughness. When the content of BAF-tfa and SiO2is1.0%and2.0%, the membrane showed the highest water contact angle (WCA) of161°and the lowest sliding water contact angle (SWCA) of2°. Furthermore, the the as-prepared membranes exhibited a certain mechanical strength, excellent stability over a wide range of pH conditions, fast and efficient separation for oil/water mixtures within30s to separate the200g mixture of oil and water (50%v/v), what is more, the oil contact angle (OCA) decreased from25°to3°. We believe that this kind of new composite organic membranes is particularly promissing for the development of easy-cleaning clothes, industrial oil-polluted water treatments and oil spill cleanup.In additon, the chemical compositon of the BAF-tfa monomer was characterized and analyzed by the nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR)spectrum, moreover physical techniques ineluding the Field Emission Scanning Eleetron Microscopy (FE-SEM), FT-IR spectrum, Contourgraph, Water contact angle, and BET specific surface area tester are used to charaterise the properties of the fibrous membranes. Meanwhile, Wenzel and Cassie theories are also applied to analyze the results of the wetting properties, which to explore the influence of its surface morphology and chemical composite to wetting property.