Water contact angle, surface treatment

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. 

Fig. 12 Surface expression of block segments in block copolymer gradient libraries after treatment to two solvents. See text for details a illustration of surface expression of PnBMA black) and PDMAEMA blue) block copolymer brush segments after water and hexane treatments b water contact angle data from three PnBMA-b-PDMAEMA block copolymer gradient libraries after hexane filled symbols) and water open symbols) treatments. (Derived from [58] with permission)...

In fact, though the surface strains were completely removed by the treatment of the Ti02 surface in a warm concentrated NaOH solution, this leads to a water contact angle of around 10-20°. At this point, a contaminant Cls peak (approximately at 285 eV) was not detected in the X-ray photoemission spectroscopy (XPS) measurement, i.e. no strains remained at the surface. On the contrary, it was confirmed that even if the surface strains remained, the highly hydrophilic conversion still occurred under UV-light irradiation [34],... 

Fig. 17 Changes in water contact angles on the (001) surface with and without the photoetching treatment...

The samples treated with KOH and washed with water were protonated by treating with 0.2 M HC1 aqueous solution at 22 °C for 5 min to yield a polyamic acid surface. The samples were washed with water (2x3 min) and isopropanol (2x3 min) and dried under vacuum. This modified surface was extensively analyzed since the polyamic acid surface is of great interest in electronic applications (14). Treatment with HC1 does not modify the polyimide, but acidifies all of the potassium polyamate surface to the polyamic acid surface. The water contact angles increased from 23°(0a)/5°(0r) to 5878°, indicating that the surface became less polar. The polyamic acid surface is less polar than the potassium polyamate surface, thus these results are consistent with the proposed reaction shown in Scheme I. 

Figure 18.6 Water contact angle changes on argon RF plasma treated PTFE surface with aging time in air 2 seem argon, lOOmtorr, 7W RF, 30 s treatment.

It can be seen that the second Ar or O2 plasma treatment lowered the water contact angles on closed system TMS polymer surfaces, but not as much as the change introduced on the flow system sample. 

Block copolymer surface was also prepared by the copper-catalyzed radical polymerization of MMA from a surface-confined macroinitiator of polystyrene (S-4) obtained by living cationic polymerization although the blocking efficiency was unknown.378 The block copolymerization increased the film thickness by 9 nm and changed the water contact angles. Other monomers such as MA and 2-(7V,7V-dimethylamino)-ethyl methacrylate were also polymerized from S-4.377 The changes in contact angles were observed by treatment of the surface with several solvents and air. 

The effect of the surface treatment for longer UV—ozone treatment times (60 min, water contact angle <30°) in terms of adherence and the laterally inhomogeneous distribution of pull-off forces provide evidence for the successful and complete oxidation of the previously hydrophobic PDMS surfaces. Upon storage in ambient conditions, one can observe that the forces gradually increase in heterogeneity with... 

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