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contact angle wetting and non wetting n.
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Contact Angle wetting and non-wetting

Contact Angle wetting and non-wetting

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Contact Angle wetting and non-wetting

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  1. Contact Angle wetting and non-wetting  Is always measured through the aqueous phase • For water drops on a surface • 0 <  < 90° Hydrophilic Surface-wets glass (glass, mica, platinum) • 90° <  < 180° Hydrophobic Surface (teflon, Rain-X on glass) • For Rain-X on Glass • Silicone compounds in the Rain-X chemically bond to the glass and causes the glass to become hydrophobic (causing water to bead-up on the glass).

  2. Finger Printing-an example of hydrophobicity • Vaporize a little Iodine carefully in a closed container. Use protective wear. • The Iodine sublimes (turns from a solid into a gas) at room temperature but is enhanced with gentle heating (the melting point in 114°C) • Put your finger print on a strip of paper and insert this carefully into the container making sure not to inhale the vapors. Since Iodine is hydrophobic, the iodine will be attracted to the oil in your fingerprint and adsorb into that oil resulting in a visible fingerprint