Contact angles and surface energy of solid substances

Introduction:

The use of contact angles in research and quality control is very popular because of its simplicity and usefulness. The technique is used in many disiplines that deals with surfaces and surface processes such as adhesion, paints, electroninc cicuits and components, cleaning etc. The surface energy can be calculated from contact angles using simplified theory. The DROPimage Standard program has been developed to make contact angle measurements and calculations easy and versatile.

Corriculum:

1. Jan Kloubek: "Development of methods for surface free energy determination using contact angles of liquids on solids". Advances in Colloid and Interface Science, 39 (1992) 99 - 142. Copies will be available.2. Manual for DROPimage Standard. Copies will be available.

Type of teaching;

Self study and lab work under partly supervision.

Learning requirements:

The student must have aquired the following abilities:

• Understand the term "surface energy of solid substances".
• Be able to measure this by means of contact angles of a selection of known liquids on a given solid.
• Understand the difference between advancing and receiding contact angles and how to do a reproducible measurement.
• Understand the difference between the methods of calculation.
• Interpret the results in connection to chemical composition of the surface.

Lab execises

• Learn the use of the instrument.
• Measurements of several liquids on polymer surfaces of different polarity and surface energy.
• Calculation of different surface energy components by means of the measured contact angles.
• Writing of lab report.