Wettability superhydrophilic

The experiment indicates that, in principle, this technique could be used to create a full length wettability gradient from superhydrophobic to superhydrophilic on a single substrate which, to our knowledge, has been rarely achieved so far [38-40],... 

Based on colloidal monolayers of polystyrene spheres, we have prepared various two-dimensional nano-structured arrays by solution routes and electrodeposition. Many ordered structured arrays generated using these methods are of surface roughness on the nano- and micro-scales, and could be superhydrophobic or superhydrophilic. The nano-devices based on such nano-structured arrays would be waterproof and selfcleaning, in addition to their special device functions. In this article, taking silica, ZnO and gold as examples of the insulators, semiconductors and metals, respectively, we report some of our recent results to demonstrate controlled wettability and superhydrophobicity of two-dimensional ordered nano-stmctured arrays with centimeter square-size based on colloidal monolayers. 

Such structured film shows different wettability from a normal silica film. Figure 4 shows the shape of a water droplet and corresponding contact angles on the silica nano-structured porous film (shown in Fig. 2) before and after surface modification. When a water droplet is deposited on the fresh silica ordered pore array, it spreads out rapidly on surface of the sample, which shows superhydrophilicity with... 

In this chapter, recent developments on different polymer surfaces with superwettability will be introduced. As mentioned above, the super-wettability on a solid surface is not solely determined by the chemical composition of that surface, but is also a result of some roughness arrangement. Theoretically speaking, all polymers can be either made superhydrophilic or superhydrophobic with the help of proper surface structures. As a result, it is... 

W. Zhu, X. Feng, L. Feng, and L. Jiang, UV-manipulated wettability between superhydrophobicity and superhydrophilicity on a transparent and conductive SnOj nanorod film, Chem. Commun., 2753-2755 (2006). 

Figure 6.4 SEM images of hydrophilic (a) and superhydrophilic (b) surfaces and their wettabilities for a water droplet (left inset) and an air bubble (right inset). Scale bars are 20 pm.

The stability of the surface wettability was studied by measuring the water contact angles at 24 h., 72 h., and 144 h. after the plasma treatment. There was a general increase in the water contact angle as a function of time after the plasma treatment. The rate of increase in the water contact angle as a function of time after the plasma treatment for the superhydrophilic surfaces was found to be significantly smaller (p < 0.05) than the hydrophilic surfaces (6 < 10°). 

Figure 17-6. The photoinduced wettability change of water and hexadecane (a) the amphiphilic conversion and (b) superhydrophilic and oreophobic conversion by UVirradiation.

Smart surfaces with reversible wettability switching between superhydro-phobicity and superhydrophilicity are of great importance due to their numerous industrial applications such as in self-cleaning surfaces, microfluidic tools, tunable optical lenses and lab-on-chip systems. - ... 

Photoinduced superhydrophilication due to water-attracting hydroxyl groups (-OH) - High water-wettability effect... 

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