From Polarimeter to Contact Angle Goniometer - Inexpensive Conversion of Laboratory Equipment

Recent decades have brought about dramatic changes in the interests of chemical researchers. Interdisciplinary areas of chemistry such as environmental chemistry, polymer science, and material science have become important parts of the undergraduate curriculum. However, introduction of these multidisciplinary areas into classical chemistry curricula often requires acquisition of specialized analytical equipment. At the same time, more traditional characterization techniques such as polarimetry have been replaced by the routine use of FT-IR and GC-MS techniques in undergraduate organic chemistry laboratories. While such classical instruments remain serviceable, they have in many cases fallen into disuse. Here we describe a simple method whereby a polarimeter is converted into a contact angle goniometer. Contact angle goniometry is an example of a traditional analytical tool that would be an asset to any physical chemistry training and that would still be of relevance to many interdisciplinary areas. Such instrumentation provides a simple and inexpensive way to introduce and measure fundamental properties such as the surface tension of a variety of materials including metals and polymers. Contact angle measurements are indispensable in the study of adhesion, wettability, and liquid thermodynamics (1 - 3). Many experiments using such measurements can be devised for traditional physical chemistry laboratory sequences. The concept of surface energy is important in materials science, chemistry, and physics. Thus it could not only enhance students' learning but also provide them with new perspective on the fascinating field of surface chemistry and physics.