Contact angle water

Fig. X-4. Water contact angle of titania-coated glass after treatment with trimethyloc-tadecylammonium chloride as a function of the number of coating treatments with 1.1% polydibutyl titanate. (From Ref. 51.)...

Instabihty in the wettabiUty behavior of OH surfaces was noticed when OH-terminated silane monolayers were exposed to hydrophobic solvents, such as CCI4 (175). Similarly, monolayers of 11-hydroxyundecane-thiol (HUT), HO—(CH2)2] SH, on Au(lll) surfaces have been found to undergo surface reorgani2ation by exposure to ambient atmosphere for a few hours (328). After that, the water contact angle reached a value of ca 60°, and only ca 25% of... 

Synthesis of siloxane-urethane copolymers from various hydroxyalkyl-terminated PDMS oligomers and aliphatic diisocyanates, such as tetramethylene- and hexame-thylene diisocyanate and HMDI was reported 333,334). Reactions were conducted either in chloroform or 1,4-dioxane and usually low molecular weight, oily products were obtained. No data were available on the molecular weights or the thermal and mechanical properties of the copolymers obtained. These products were later cross-linked by a peroxide. Resulting materials were characterized by IR spectroscopy and water contact angle measurements for possible use as contact lenses. 

The chitosan-heparin polyelectrolyte complex was covalently immobilized onto the surface of polyacrylonitrile membrane. The immobilization caused the water contact angle to decrease, thereby indicating an increase in hy-... 

The FAS SAMs on the magnetic heads lead to a considerable improvement on tribological and corrosion-resistant properties, a high water contact angle, and electron charge adsorption-resistant property of the magnetic head. 

The Influence of the PFAM Concentration on the Film Thickness, the Water Contact Angle, and the Surface Topography... 

The values of the water contact angle of the PFAM film on the slider surface also increased with the concentration of PFAM solutions (Fig. 5 [26]). The water contact angle increased up to 121 ° at 200 ppm from the initial values of 88.4° without the PFAM film, indicating that the PFAM had covered the slider surface well. For N-Hexane, the contact angle was only about 48°, but the contact area was much larger than that on the slider surface without the PFAM film as shown in Fig. 6. 

Fig. 5—The thickness and water-contact angle of PFAM thin film as a function of solution concentration.

Fig. 21—The thickness and water contact angle of FTE SAMs on the DLC surfaces as a function of the immersing time in a 10 mM FTE solution at temperature of 20°C (a) film thickness of FTE SAM, and (b) water contact angle.

The solution concentration also has an influence on the formation of the SAMs. The maps of X-ray photoelectron spectra show that the C(ls) peaks for the samples in 1 mM and 5 mM FTE solutions with 24 h immersing are similar to those in Fig. 20(a), which indicates that there was hardly any SAMs on the DLC surface. The thickness of FTE SAMs and the water contact angle value increased with the immersing time. Hu et al. [26,34] obtained FTE SAMs with a thickness of 1.2 nm and a water contact angle value of about 110° by immersing a sample in a 10 mM FTE solution for 35 hours as shown in Figs. 21 (a) and 21(b). 

For the three sorts of molecules, the film thickness and the water contact angle value of the SAMs grow with increasing chain length. In the immersing time of 1 h, the film thickness obtained is 0.48 nm, 0.8 nm, 1.2 nm, corresponding to the molecules with the number of carbon of 3, 8, and 10, respectively, and the contact angle value is 94°, 107.6°, 110.4°. 

Such polymers are as hydrophobic as poly(tetrafluoroethylene) (Teflon), with water contact angles in the range of 107°. But, unlike Teflon, polyphosphazenes of this type are easy to fabricate, are flexible or elastomeric, and can be used as coatings for other materials. ... 

Weight on Methacrylate) the Water Contact Angles of Poly(Methyl -Poly(Dimethyl Siloxane) Graft Copolymers ... 

Upadhyay et al. [98] used primarily correlated XPS and water contact angle measurements to study the surface degradation and recovery of amorphous films of a PMMA and a poly (aryl ether ether ketone) (PEEK). Surface modification of the films was carried out in a dielectric barrier discharge (DBD) unit, samples being treated with different dose levels of dielectric discharge. The modified (treated) samples were then stored for one month and re-examined. Figure 35 shows C(ls) and 0(1 s) XPS envelopes and their curve-fitting deconvolutions,... 

Fig. 3 Relationship between water contact angles on mixed SAMs and the number of adherent cells. HUVECs (open circles) and HeLa cells (filled circles) were allowed to adhere for 1 h. The averages ( SEM) of five experiments are shown [21]...

The hydrophilic SiO substrate)static water contact angle 0=3O°) was prepared by vapor-deposited SiO onto a Formvar substrate[4], with which an electron microscope grid(200-mesh) was covered. The relatively hydrophobic siliconized substrate(0=9O°) was also prepared by surface siliconized treatment a collodion-covered electron microscope grid was dipped into an aqueous solution of silane coupling agent. 

Table 9.4. Water Contact Angle of Fluorine-Containing Poly(Carbonate)s6...

Crystallinity of these hexafluoroisopropylidene-unit-containing poly(ketone)s is low except for poly(sulfide ketone) (13). The water contact angle for the fluorine-containing poly(ketone) films is high, being 98° for poly(ether ketone) (11), from 2,2-bis(4-carboxyphenyl)-l,l, l,3,3,3-hexafluoropropane(15) and 96° for poly(sulfide ketone) (13) from 15, whereas it is 78° for poly(ether ketone) from 2,2-bis(4-carboxy-phenyl)propane (16) and 74° for the poly(sulfide ketone) from 16. This result indicates that the substitution of isopropylidene units of poly-(ketone)s with hexafluoroisopropylidene units has a remarkable effect on the surface properties of poly(ketone) films. 

The cast films ofpoly(azomethine)s are transparent but pale to deep yellow in color. The water contact angles of fluorine-containing poly(azomethine)s films from diamine (17) are 80° for terephthalaldehye (19) and 75° for isophthalalde-hyde (20) as dialdehyde component (Table 9.9).20 These low values of water contact angles are attributed to the lower fluorine content in these polymers. 

TEM was coated with 6 nm of the random copolymer and 34 nm of the block copolymer. Annealing at 170 °C and exposure to acetic acid generates the desired nanoporosity. After floatation of the film on a dilute aqueous solution of HF the authors picked it up on a TEM grid. The fate of the random copolymer was not described. Water contact angle and X-ray photoelectron spectroscopy (XPS) experiments were consistent with the migration of the PMMA chains to the top of the thin film to generate the desired porosity. 

Table 4.1 The effect of chemical modification on water contact angles...

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