【作者】 杜凯；

【导师】 孙立涛；

【作者基本信息】 东南大学 ， 微电子学与固体电子学， 2017， 硕士

【摘要】 进入21世纪以来,现代城市建筑墙体灰尘沾污等问题逐渐突出。随着环保意识的普遍增强,人们采用人工清洗等多种方式应对上述问题。但这些方法存在工作量大、成本高等问题。相比之下,具有自清洁功能建筑墙体材料脱颖而出。自清洁的核心在于超疏水性和光催化性。超疏水性是指材料表面与水接触角大于150°,滚动角小于10°,优异的憎水性使其在自清洁、流体减阻、油水分离等领域中有着重要的应用前景。光催化性是指材料在特定光源照射下能将有机物分解,典型如TiO₂,但其存在光谱吸收范围窄、电子-空穴对分离效率低等问题,限制了其进一步应用。本文通过溶胶凝胶法制备出TiO₂-SiO₂（下文简称TS）,并分别与PDMS、甲苯按比例混合,采用浸渍提拉法涂覆于载玻片表面,在构造粗糙表面结构的同时固化PDMS以降低表面能,制备出具有光催化效应的超疏水材料。并对其微观结构、光催化性、超疏水性进行了探究和分析:（1）通过前驱体钛酸四丁酯水解而成的无定形偏钛酸凝聚粒子制备出TiO₂,并采用溶胶凝胶法,对TiO₂溶胶进行SiO₂复合改性。之后对样品进行不同温度的退火处理,得到复合材料TiO₂-SiO₂（n（Si）:n（Ti）=0.3）。结果表明:复合材料表面呈毛茸状,同时还存在孔状结构。经退火处理后,表面孔状结构分布更为密集、均匀。SEM、XRD表征结果显示,当退火温度为600℃或更高时,材料表面出现较大面积乳突状结构,且样品中TiO₂为锐钛矿型;（2）采用浸渍-提拉法,将复合材料与PDMS、甲苯按质量比4:1:5混合涂覆于载玻片上,室温下烘干,即得TiO₂-SiO₂@PDMS（下文简称TS@PDMS）。接触角仪测量结果表明:以不同退火温度下TiO₂-SiO₂为基础制得的TiO₂-SiO₂@PDMS与水有着不同的接触角。其中,经600℃退火的TiO₂-SiO₂@PDMS与水接触角高达157°。此外,由于样品表面超疏水性,散落于其表面的灰尘可被滚动的水珠带走,实现物理自清洁;（3）将上述TiO₂-SiO₂、TiO₂-SiO₂@PDMS用于光催化降解一定浓度的亚甲基蓝溶液、甲醛气体、苯气体。结果表明:光照2 h时,经600℃退火处理的TS-600对亚甲基蓝降解率为99.6%,略高于同等条件下TS-600@PDMS 95.9%的降解率;此外,光照3h时,TS-600@PDMS可分别实现降解95.5%甲醛、95.7%苯。不难得出,负载于载玻片上的TS@PDMS在保持光催化活性的同时,具备了超疏水性,在自清洁领域具有广阔的应用前景。更多还原

【Abstract】 Since the beginning of the 21st Century,dust pollution on building wall in modern city is becoming increasingly severe.With the general evoking awareness of environmental protection,people have taken various ways to deal with this problem,for example,manual cleaning.However,among these methods heavy workload and high cost are also the trouble.So building wall material with self-cleaning function stands out.The core of self-cleaning lies in superhydrophobicity and photocatalytic activity,superhydrophobicity refers to contact angle between water and sueface greater than 150° and rolling angle less than 10°.The excellent hydrophobicity makes it possible in applications of self-cleaning,fluid drag reduction,oil-water separation and so on.Photocatalytic means that organic matter can be decomposed when under a specific light source,and TiO₂ is a kind of semiconductor material with certain photocatalytic performance.However,the narrow spectral absorption range and low separation efficiency of electron-hole pairs limit its further development.In this thesis,TiO₂-SiO₂（TS）was prepared by sol-gel method and mixed with PDMS of a certain percentage.The mixture was then coated on the surface of glass slides by a strategy known as "impregnation-pulling".A rough surface structure is constructed and the surface energy can be reduced by adding PDMS.The properties of microstructure,photocatalytic activity and hydrophobicity of the as-obtained material have been investigated and analyzed:（1）TiO₂ was prepared by hydrolysis of the amorphous,meta-titanate agglomerated particles with tetrabutyl titanate,and the sol-gel method was used to functionalize the TiO₂ sol.After the samples had been annealed at different temperatures,the TS composites were obtained（n（Si）:n（Ti）=0.3）.The results show that the surface of the composites is fluffy presenting porous structure.After annealing,the surface porous structure is denser and more uniform.The results of SEM and XRD also show that when the annealing temperature is set above 600℃,the large fraction of the microstructures of material surface resembles to that of a lotus leaf,in which TiO₂ is mainly anatase-type.（2）The above composite material TiO₂-SiO₂ was mixed with PDMS and toluene at ratio of 4:1:5.The mixture was coated on the glass slides,dried at room temperature or in an oven.The result of contact angle measurements shows that TiO₂-SiO₂@PDMS based on TS at different annealing temperatures has different contact angles.Among them,the 600℃-annealed,TS-600@PDMS has the largest contact angle up to 157°.Besides,the super-hydrophobic surface of the sample endows physically self-cleaning property,meaning that the dust scattered on the surface can be carried away by water droplets;（3）The TiO₂-SiO₂ and TiO₂-SiO₂@PDMS have been applied in photocatalytic degradation of methylene blue solution,formaldehyde steam and benzene steam.The results showed that TS annealed at 500℃ has the highest degradation rate,and the degradation rate was 99.9%when irradiated under UV for 2h,slightly higher than that of TS-600.When it comes to the degradation rate of formaldehyde and benzene exposed to UV for 3h,the degradation rate is 95.5%and 95.7%,respectively.According to these results,it is natural to conclude that TS@PDMS coated on glass slides possess both super-hydrophobicity and photocatalytic activity,which is promising to have wide application prospects which require self-cleaning.更多还原