Preparation Of Superhydrophobic Coattings Based On Waterbrone Polyurethane And Application In Oil-water Separation

Superhydrophobic coating is a new type of special wettable coating and has special properties such as self-cleaning,anti-icing,anti-bacteria and anti-adhesion,and it is widely used in various aspects of daily life.Three kinds of superhydrophobic coatings with excellent performances were prepared in this paper,in which waterborne polyurethane served as a substrate material,while nano particles created surface roughness.Firstly,a series of organosilicone modified WPU emulsions(SiWPU)were prepared by using isophorone diisocyanate(IPDI),2,2-dimethyloipionic acid(DMPA),oligomer diol and aminoethylaminopropyl polydimethylsiloxane(AEAPS).Effect of the oligomer diols on the hydrophobic performance of WPU were studied,as well as the effect of the amount of AEAPS on the performance of SiWPU was further discussed.The molecular structure of SiWPU was characterized by Fourier transform infrared spectrum(FT-IR),thermogravimetric analysis(TGA),atomic force microscope(AFM),Scanning electron microscope(SEM),X-ray diffraction(XRD).The results showed that when polytetramethylene(PTMG)was as the soft segment,mass fraction of AEAPS was 6%(basing on the weight of polyurethane prepolymer),the SiWPU emulsion and film showed good properties.Compared to the unmodified WPU film,Si WPU film showed better hydrophobicity,mechanical property,water resistance,thermostability and greater microphase separation degree.XRD results showed that the crystallinity of these SiWPU film was rather low and with the introduction of AEAPS,the crystallization ability of WPU was affected.Secondly,the conductive superhydrophobic coatings with sandwich-like structure of “SiWPU-MWCNTs-SiWPU” were fabricated by using SiWPU and multi-wall carbon nanotube(MWCNTs).To improve the dispersibility and stability of MWCNTs in ethanol,octadecylamine was grafted onto the surface ofMWCNTs.The structures and properties of the modified MWCNTs were characterized by FT-IR,TG,XPS,transmission electron microscope(TEM)and stability analyzer.The results showed that the octadecylamine was successfully grafted onto the surface of MWCNTs and the grafting ratio was about 10.97%.Meanwhile,the modified MWCNTs showed good dispersibility and agglomerate phenomenon was significantly improved.The surface microtopography,wettability,conductivity,electric heating characteristic,mechanical stability and UV resistance of composite coatings were discussed.The results showed that these composite coatings with a sheet resistance of 1.1 ± 0.1 kΩ/sq exhibited high static contact of 158.1 ± 2.0° and low sliding angle below 1°.Furthermore,the resultant coatings demonstrated excellent wear resistance and ultraviolet resistance.Thirdly,the copper mesh-based superhydrophobic surfaces with nest-like structure were prepared by one-step spray nanocomposites composed of octadecylamine modified MWCNTs and SiWPU.The results of SEM and contact angle measurement revealed that after treatment the nest-like structures were formed on the copper mesh surface and the copper mesh showed a high water contact of 162.3 ± 1.2° and an oil contact angle of 0°.Thus,it can be used to separate a series of oil/water mixtures,such as kerosene/water,toluene/water,tetrachloromethane/water,petroleum/water and hexane/water.The separation efficiency was more than 93.79% and stable recyclability could be obtained.In addition,the as-prepared mesh could maintain its superhydrophobic property after soaking in corrosive solutions(1 M NaOH,HCl,NaCl)for 24 h.Finally,the superhydrophobic meshes that can repel hot water and possess excellent mechanical stability were fabricated by one-step spray of Si WPU and hydrophobic silica nanoparticles onto the copper mesh.The as-prepared superhydrophobic/superoleophilic mesh could separate the hot oil/water mixture with the temperature more than 100℃.The SEM results and contact angle measurement revealed that after treatment the rough structures with massive nanoporous were formed and this micro-nanometer hierarchical structure on the copper mesh surface had low solid friction,so the water contact angle reached to162.5 ± 1.4° while the sliding angle was less than 0.4°.In addition,the as-prepared mesh was successfully used to separate a series of oils from watersuch as kerosene,toluene,petroleum ether,tetrachloromethane and hexane.The separation efficiency was above 93.71% and it can be stable recyclability.