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The Effect Of Temperature On Surface Chemistry

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3. Theoretical Background
3.1 Surface Chemistry
Weather a surface is hydrophobic or hydrophilic largely depends upon surface chemistry. Each and every surface has energy which is proportional to area .For liquids surface tension is identical to surface energy. And we know everything moves towards reducing its energy therefore drops tend to be spherical. But what about droplets on a solid surface. Drops form an inverted cup like structure and the angle made by drop surface with the solid surface is called the contact angle. Every surface has Surface Energy. There is surface energy or surface tension between air-solid-liquid. Contact angle is defined as the equilibrium angle made by liquid surface with the solid surface.Young’s equation describes the force balance between the interfacial tensions formed at the solid–liquid–vapor contact line.
3.2 Contact Angle

When a drop of liquid is placed onto a solid surface, it forms a so-called contact angle (θ). The Young’s equation for the contact angle of a liquid can be applied only to a flat surface and not to a rough one. The contact angle of a liquid on a perfectly smooth and chemically homogeneous solid surface is given by Young’s equation : cos θ = ( σsg – σsl )/ σlg where σsg, σsl and σlgare the interfacial tensions of the solid-vapor, solid-liquid and the liquid-vapor interface respectively .

From the above Youngs equation we can find the angle which the liquid

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