Synthesis And Modification Of Rutile Titania-silica Nanocomposites

In recent years,many issues about "tile rain" felled from buildings have been reported in all around the country,which threatened the personal safety of urban residents.In some province and cities,the governments have drawn up laws and regulations to ban the use of stone external wall decoration materials since 1997.However,the domestically-made exterior wall paints could not practically replace the stone wall decoration materials due to their defects of poor decoration,low weather resistance and poor stain resistance.Therefore,it is of great improtance to develop the multifunctional external wall decorative materials with good decoration,self-cleaning capability,good weather resistance and low cost.The key of fabricating this kind of materials is the preparation of superhydrophobic coatings.Superhydrophobic surfaces can be by far synthesized either by superhydrophobic modification of constructed rough surfaces with micro/nano structure or by roughening the surface of hydrophobic materials to create well-ordered micro/nano structure.In either case,apropriate inorganic composite?such as ZnO,TiO₂,Co₂O₃,SnO₂,SiO₂,etc.?play a momentous role for the formation of superhydrophobic rough surfaces.In this paper,rutile-TiO₂-SiO₂ based on organic and inorganic precursors were synthesized by using improved sol-gel and hydrolysis co-precipitation methods,respectively.The optimal Ti/Si molar ratio and calcining temperature for the synthesis of rutile-TiO₂-Si O2 were investigated using X-ray Riffracation and X-ray Photoelectron Spectroscopy.After TMCS and NH₄F surface modification,the rutile-TiO₂-SiO₂ exhibited excellent hydrophobic and amphiphobic performance,suggesting their potential applicability in exterior wall coatings.This paper is divided into five chapters,each chapter is introduced as follows:In chapter one,the superhydrophobic bio-surface of natural world andthe theories of surface wettability and foundation of superhydrophobic surface of this paper were summarized.The preparation methods and various applications of superhydrophobic surfaces materials were also elaborated,furthermore,the construction of rough surfaces with micro/nano structure was reviewed and the problem existed was revealed.In chapter two,parsimoniously introduced the experimental reagents and instruments,preparation of rutile titania-silica based on organic and inorganic precursors by using sol-gel and hydrolysis co-precipitation methods,respectively,followed sequentially by calcination and surface modification.In chapter three,rutile-TiO₂-SiO₂ were synthesized from TEOS and TTIP by an improved sol-gel method followed with high temperature calcination and modification with trimethylchlorosilane.The obtained rutile titania-silica were characterized by XRD,XPS,BET,SEM,FTIR and WCA.The results showed that rutile crystal structure was achieved at Ti/Si molar ratio of 5:1 and calcination temperature of 1100?.After TCMS modification,the rutile-TiO₂-SiO₂ exhibited superhydrophobicity?WCA of 154.7°?.In chapter four,rutile-TiO₂-SiO₂ were synthesized by an improved hydrolysis coprecipitation method using low-cost sodium metasilicate and titanium oxysulfate as precursors and calcined at different temperatures.The rutile-TiO₂-SiO₂ nanocomposites were modified with TMCS and NH₄F as surface modifying agent.It was found that the resulting TiO₂-SiO₂ had a Ti/Si molar ratio of 5:1 calcined at 800? and showed a single-phase rutile-type structure with a high specific surface area.The TMCS and NH₄F modified rutile-TiO₂-SiO₂ exhibited an hydrophobicity and amphiphobic performance.In chapter five,the paper was summarized,the development prospect and applicarion of superhydrophobic surface materials was proposed.