Superhydrophilic surfaces

Keywords Bubble, superhydrophilic surface, sliding angle, contact angle hysteresis, adhesion force... 

When the substrates were titled, the captive air bubble sitting on the superhydrophilic surface moved and slid up more easily at a lower sliding angle than on a hydrophilic surface. For example, Figure 6.5 shows the profiles of the air bubbles of the same volume (20 pL) on the hydrophilic and superhydrophilic surfaces, at both the initial horizontal position and the inclination at a sliding angle. When an air bubble sits on the micropillared superhydrophilic surface immersed in water, there is no direct contact between the bottom trench of the micropillared solid surface and... 

Figure 6.5 (a-b) Profiles of air bubbles on hydrophilic and superhydrophilic surfaces, respectively, in a horizontal position after stabilization, (c-d) Deformation of the air bubble at inclination (at sliding angle) and the change in contact angles. On the hydrophilic surface (c), the air bubble (20 pL) started to slide up at 13 with the maximum/minimum contact angles of 145 and 124 , respectively. On the... 

Figure 6.6d shows the experimentally measured sliding angles with varying bubble volume. As can be expected from Equation (6.7), the sliding angle on the superhydrophilic surface is much lower than that on the hydrophilic surface due to the lower contact angle hysteresis (CAH) or... 

From the experimental results shown in Figure 6.6, the retentive force factors (k) which best fitted Equation (6.7) were obtained for both hydrophilic and superhydrophilic surfaces. They were 2.1 and 0.4 for the hydrophilic and the superhydrophilic surfaces, respectively. Using these k values in Equation (6.7), Figure 6.7 shows the adhesion forces of bubbles with varying volumes on the superhydrophilic surface, as compared to a hydrophilic surface. As can be expected from Figures 6.6a and 6.6c, the adhesion force of a bubble on the superhydrophilic surface is much lower than that on the hydrophilic surface due to the significantly lower contact width and... 

Figure 6.7 Adhesion forces of air bubbles of varying volumes on the hydrophilic and the superhydrophilic surfaces. (The solid lines are drawn to show the trends).

RF Plasma Treatment of Neptune Grass Posidonia oceanica) A Facile Method to Achieve Superhydrophilic Surfaces for Dye Adsorption from... 

Surfaces that possess water contact angles less than 5° within 1 second of drop deposition are called superhydrophilic surfaces. Materials with superhydrophilic surfaces have the highest water wetting property [4-6]. Surfaces that exhibit water contact angles of greater than 150° are called superhydrophobic surfaces [3,7]. 

Figure 12.4 Water spreading on the reptiles superhydrophilic surfaces [23].

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°). 

Superhydrophilic surface property (9 < 5° within 1 second of droplet contact) was achieved at high-energy argon-plasma (180 kj) and low-energy... 

J. Drelich, E. Chibowski, D. D. Meng and K. Terpilowski, Hydrophilic and superhydrophilic surfaces and materials. Soft Matter, 7,9804-9828 (2011). 

---