Study On Preparation And Properties Of Waterborne Polyurethane And Inorganic Nano-particles Superhydrophobic Composite Coating

We report fabrication method of robust,transparent and superhydrophobic organic/inorganic composite coating,having simple,low cost,effective and environmentally friendly characteristics.Firstly,a waterborne polyurethane(WPU)emulsion and fluorinated silica(F-SiO₂)nanoparticle dispersion were synthesized.Subsequently the polyurethane/fluorinated silica(WPU/F-SiO₂)superhydrophobic surfaces with low surface energy were constructed by in order spraying WPU emulsion and F-SiO₂ nanoparticle dispersion on substrates.The coating formation,morphology change,and effects of fluorine content on wear resistance and hydrophobicity of the coating were further investigated.In addition,oxidation-reduction initiation system of WPU and F-SiO₂ dispersions were synthesized,and the redox system of WPU/F-SiO₂ nanocomposite coatings(R-WPU/F-SiO₂)were prepared by physical blending and spray deposition methods.The effects of different coating methods on the properties of nano-composite coatings were studied.Morphology,internal structure,chemical composition,transmittance,the size and size distribution and surface element of the composite particles were characterized by scanning electron microscopy(SEM),transmission electron microscopy(TEM)fourier transform infrared spectrometer(FTIR)and dynamic light scattering(DLS),UV spectrophotometer,X-ray photoelectron spectroscopey(XPS)and Nuclear magnetic spectrum analyzer(NMR),respectively.Moreover,the surface morphology of nanocoatings and its hydrophobicity and anti-UV performance were studied by SEM,contact angle instrument and ultraviolet aging tester,respectively.The wear resistance,oil resistance and adhesion properties of nano-coatings were tested by abrasion meter,oil resistance test and cross-hatch method,respectively.The results showed that by changing the mass ratio of FAS to TEOS to control the content of fluorine in F-SiO₂ nanoparticles,the binding strength of-OH in F-SiO₂ to-NCO in WPU was investigated.The optimum wear resistance ratio of WPU/F-SiO₂ nano-composite coating was obtained.The robust composite coating had excellent superhydrophobicity and good optical transparency.After 250 cycles of abrasion,long period of ultraviolet irradiation,the nanocomposite coating still exhibited excellent properties including good self-cleaning,transparency,abrasion resistance,aging resistance and strong adhesion.Even after being oil-contaminated,the WPU/F-SiO2 composite coatings still possessed antifouling and superhydrophobic properties.These excellent properties were attributed to the fact that the viscoelastic WPU provided a strong substrate for anchoring superhydrophobic F-SiO₂ nanoparticles,which lays the foundation for the construction of nano-composite coatings with strong mechanical performance.As a result,the WPU/F-SiO₂ nano-composite coatings have broad application prospects in self-cleaning surface and protective coatings of various substrates.