Water contact angles, polymer samples

Films of purified PVCa were cast from methylene chloride solution on quartz plates. The solvent was allowed to slowly evaporate to give smooth, clear films with a thickness of ca. 5.0 nm. Contact angle measurements using water droplets were measured with a standard contact angle goniometer. Samples were photo-lysed in air with polychromatic light from a 150 watt xenon arc. Contact angles were measured after various times of irradiation to monitor the formation of oxidation products at the surface of the polymer films. 

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. 

Sample Peroxides content (moPg of polymer) [q]" Water contact angle (°) of the film cast from acetone solution [0]/[C] ratio ... 

Figure 36 shows a 3D plot of a scaiming Kelvin probe measurement of an iron sample that was coated with a 5-mn-thick HMDS plasma polymer on one half of the sample surface prior to the deposition of the primer [115]. The water contact angle... 

The water contact angles of the modified polymers were measured using a Lorentzen Wettre goniometer and triply distilled water as the contact angle liquid. At least 5 measurements were performed for each sample and the mean value was taken as the final result. 

There are three major complications in contact angle studies of proteins and other water sensitive polymers. First, no simple or safe method of guaranteeing the cleanliness or uniformity of specimen surfaces is available the initial purity of the sample must be relied upon as the primary criterion of surface uniformity. Second, there is a strong effect from adsorbed water molecules which remain on the surface and... 

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