Preparation And Properties Of Superhydrophobic Surfaces With Micro-nano Strcture

Superhydrophobic surfaces were defined as “water-hating” surfaces that have extremely high water contact angles(CA > 150°)and low sliding angles(SA <5°).Because of their unique wetting property,the superhydrophobic surfaces have outstanding application potentials in construction materials,marine vessel manufacturing,textile making,environmental engineering,desalinization,corrosion protection,etc.The realization of superhydrophobicity is usually based on the combination of constructing special surface hierarchal structures and making low energy surfaces.However,commercialization of realizing superhydrophobic coatings is still facing such challenges as low mechanical robustness,poor thermal and chemical stability,low weather resistance,high manufacturing cost,complex and tedious processing steps,etc.In order to solve the problems mentioned above,this thesis work designed and manufactured a series of robust superhydrophobic surfaces.The influence of sizes,composition and shapes of the nanofiller particles on the mechanical robustness of the prepared coatings was studied systematically.In this thesis work,different functionalities such as antibacterial,flame-retarding and self-healing were integrated into the superhydrophobic coatings.The content of this thesis is summarized as below:(1)Introduction.In this chapter,the concept and fundamentals of wettability were introduced.The manufacturing methods of superhydrophobic surfaces were also reviewed and the limitations of current preparation methods were summarized to introduce the motivation of this thesis research.(2)Design,synthesis and characterization of abrasion-resistant superhydrophobic coatings.In this chapter,a special spray coating(Liquid Glass)was designed and manufactured,which solidified quickly into a transparent and abrasion resistant film when applied onto a targeted substrate.Nano and micron sized particle fillers with different compositions,sizes and shapes were added into the spray coating to study the influence of these parameters on the mechanical robustness and performance of the final superhydrophobic coatings.With optimization,a superhydrophobic coating with contact angle of 162° and a sliding angle of less than 2° was obtained.The abrasion test showed that the coating abraded by sandpaper(#400)at an applied pressure of 20 k Pa for 150 times remained superhydrophobic.Such a coating also showed a remarkable performance in corrosion protection of steel plate in highly acidic(p H=1),highly basic(p H=14)and salty environments.The coating was also found to perform well in extreme temperatures(-30? to 180?)(3)Design and preparation of abrasion-resistant and antibacterial superhydrophobic coatings.A wide spectrum of antibacterial composite filler particles(Ag-Zeolite)was designed and prepared by in situ growth of nano-silver particles on micron-sized natural zeolite substrates.The synthesized Ag-Zeolite particles were added into the spray coating developed in Chapter 2 and found to further boost the mechanical property of coating and provide the coating with strong antibacterial property as shown by high inhibition rates greater than 95% against both S.aureus and E.coli.(4)Design and preparation of superhydrophobic multi-functional fabrics.In this chapter,a specialized fabric was developed to possess a multifunctional property including superhydrophobicity,fire-retardancy,self-healing and antimicrobial property.To achieve such multi-functionality,base cotton fabrics were treated by a layer-by-layer(Lb L)deposition method,in which each layer features its own functions.Specially designed interlayer interactions and integration of different functionalities led to a functionalized fabric with water contact angle and sliding angle of 156° and 3°,respectively.Such a fabric showed excellent physical and chemical stability after abrasion by sandpaper for 150 times and washed for 30 times,maintaining its desired performance.Such a fabric can self-distinguish the flame set on it and provide inhibition rates above 99% against both S.aureus and E.coli.The preparation methods of superhydrophobic coatings introduced in this thesis are simple,efficient and cost effective,thus suitable for large-scale industrial production and applications.