第六章疏水材料--超疏水

1、Supperrepellent material,1 Wettability,Youngs equation: cos=(SV SL)/ LV Hydrophobic: 90 ; Hydrophilic： 90 .,Wettability is a fundamental property of material surfaces,Water contact angle (WCA) larger than 150 and extremely low WCA hysteresis or sliding angle less than 10.,Superhydrophobicity,Sliding

2、 angle,mg(sin)/ = (cosa-cosr) a Advancing contact angle, r Receding contact angle, m-The quality of water drop， g-Acceleration of gravity ， -Diameter of water drop， -Surface Energy of water drop。 m，g， are constant ，then： sincosa cosr.,LOGO,A wide spectrum of applications,LOGO,soysauce,LOGO,Water col

3、lector in the desert,LOGO,Antifouling coating,The undesirable accumulation of microorganisms, plants, and animals on artificial surfaces immersed in sea water. High frictional resistance and fuel consumption, due to generated roughness, Deterioration of the coating so that corrosion, discolouration,

4、 and alteration of the electrical conductivity of the material are favoured.,Low surface energy coating for mitigating marine biological fouling,Antifouling coating,Drag reduction,Self-cleaningmaterials,Antifrost,LOGO,Antifogging surfaces,局部放大,Oilwater separation,Supperrepellent material innature,LO

5、GO,出淤泥而不染， 濯清漣而不妖。 -宋.周敦頤愛蓮說,超疏水的荷葉和表面結(jié)構(gòu)（a)球形的水滴滴在荷葉表面（b)荷葉表面大面積的微結(jié)構(gòu)（c)荷葉表面單個(gè)乳突（d）荷葉表面的納米結(jié)構(gòu),Lotus effect,Cicadas wings,蟬翼表面由規(guī)則排列的納米柱狀結(jié)構(gòu)組成納米柱的直徑大約在80 nm，納米柱的間距大約在180 nm規(guī)則排列納米突起所構(gòu)建的粗糙度使其表面穩(wěn)定吸附了一層空氣膜，誘導(dǎo)了其超疏水的性質(zhì)，從而確保了自清潔功能。,LOGO,Butterfly wings,2、 The theoretics of Supperrepellent material,Wettability,C

6、assie model,Wenzel model,Youngs equation,For smooth, flat, uniform solid surface, the relationship between contact angle and surface energy can be described by Yongs equation (Thomas Young, 1805 ) : cos=(SV SL)/ LV,Interfacial tension: SV 、 SL 、 LV,Yongs equation,Hydrophobic surface,The surface free

7、 energy of materials is related to the species and the concentration of the functional surface groups,Functional surface,Hydrophilic groups: OH、CHO、 COOH、NH2 Hydrophobic groups： CnH2n+1、 CH=CH2、 C6H5、X、NO2 CF3,Fluorinated polymer,CH2 (36 dyn cm-1) CH3 (30 dyncm-1) CF2 (23 dyn cm-1) CF3 (15 dyn cm-1)

8、 The reason of choosing fluorosilicone Low surface energy and high surface-active of CF3 group Improves the adhesion and compatibility,self-assembly,For smooth, flat, uniform solid surface, the highest contact angle is only 119。,Real solid surface with concave-convex structure,Wenzel model,Cassie mo

9、del,Cos*=,=r COS ,Wenzel model：,Cos*=,=r COS ,Providing =110，if r0.53， * will be larger than 150,Wenzel model,Cassie model,Cos= fcos+(1-f)cos180 = fcos+f-1,Area fraction f=a/(a+b),lets assume that =110，if f is less than 0.2, will be larger than 150.,Cassie model,Providing CA between liqiud and air i

10、s 180,PAN Nano fiber material,LOGO,Self-cleaning effect,Dirt,3、The fabrication of Supperrepellent surface,Modifying a rough surfaces chemical components,LOGO,Turning a Surface Super-Repellent Even to Completely Wetting Liquids,Tingyi “Leo” Liu, et al., Science, vol. 346, pp.1096-1100, 2014.,Template

11、 method,Etching,McCarthy等在聚四氟乙烯 (PTFE)存在下, 用射頻等離子體刻蝕聚丙烯 (PP)制備出粗糙表面。表面與水的前進(jìn)角/后退角可達(dá) A/R = 172/169。,利用射頻等離子體刻蝕法在不同刻蝕時(shí)間得到的聚丙烯掃描電子形貌圖: ( a) 0 min, ( b) 30 min, ( c) 60 min, ( d) 90 min,( e) 120 min, ( f) 180 min,Chen等利用納米球刻蝕的方法首先得到了排列整齊的單層聚苯乙烯 (PS)納米珠陣列 ,再用氧等離子體處理以進(jìn)一步減小納米珠的尺寸從而得到粗糙表面。在其表面覆蓋 20nm厚的金膜并用十八

12、硫醇(ODT)進(jìn)行修飾可以增強(qiáng)其疏水性。通過調(diào)整 PS納米珠的直徑 (440-190 nm)可以控制表面接觸角的大小 (132-168 )。,氧等離子體處理后的超疏水 PS納米珠陣列表面,LOGO,LOGO,Chemical vapordeposition,江雷等利用化學(xué)氣相沉積法(CVD)在石英基底上制備了各種圖案結(jié)構(gòu)的陣列碳納米管膜, 結(jié)果表明, 水在這些膜表面的接觸角都大于 160, 滾動(dòng)角都小于5, 納米結(jié)構(gòu)與微米結(jié)構(gòu)在表面的階層排列被認(rèn)為是產(chǎn)生這種高接觸角、低滾動(dòng)角的原因。,LOGO,4 Research plan,In order to fabricate superhydroph

13、obic or superhydrophilic surfaces based on sub-micron structures,I think my research in UW can be divided into three stages.,LOGO,Firstly,the fabrication of artificial structured surface. Several artificial structured surfaces have been disgined. If thesenanopillar and mushroom shaped nanopillars ar

14、ray with piece of 10 mm10 mm can be prepared by electroplate copper or nickel nanopillars?,LOGO,LOGO,Secondly, modify its components by surface fluorination.,LOGO,Lastly, the fabrication of hierarchical structures. If the property of above structured surface after surface fluorination can not meet superhydrophobic or superhydrophilic requirement, I will increase surface roughness by preparing hierarchical structures on above artificial structured surface.,LOGO