Introduction:
The surface tension of liquids is useful to investigate adsorption, detergency, surface kinetics, etc. It can be measured by many different methods and instruments. The drop shape method is especially suited to measure changes of surface tension by time, and is therefore useful to investigate dynamic processes at the surface and interface of liquids. The DROPimage Advanced program has been developed to make the drop shape method easy and versatile.
Curriculum:
1. F.K.Hansen: "Surface Tension by Image Analysis. Fast and Automatic Measurements of Pendant and Sessile Drops and Bubbles", J.Colloid Interface Sci., 160 (1993), 209-217.
2. R.Myrvold and F. K. Hansen: "Surface Elasticity and Viscosity From Oscillating Bubbles Measured by Automatic Axisymmetric Drop Shape Analysis", J.Colloid Interface Sci., 207 (1998), 97-105.
3. T. Fr?myr, F. K. Hansen, A. Kotzev, and A. Laschewsky: "Adsorption and Surface Elastic Properties of Corresponding Fluorinated and Nonfluorinated Cationic Polymer Films Measured by Drop Shape Analysis", Langmuir 2001, 17, 5256-5264.
4. Manual for the DROPimage Advanced program.
Type of teaching:
Self study and lab work under partly supervision.
Learning requirements:
The student must have aquired the following abilities:
- Understand the terms "surface tension" and "surface elasticity".
- Be able to measure surface tension by the pendant drop method by means of the Drop Shape instrument and the DROPImage Advanced program.
- Be able to measure surface tension and surface elasticity by the sessile bubble method using the oscillatory mode of the same instrument/program.
- Be able to use the output from the DROPimage program for the plotting and presentation of the results in Origin.
Lab execises
- Learn the use of the instrument.
- Measurements of surface tension of pendant drops of water in air, using a simple surfactant and a surface active polymer.
- Measurements of surface tension as a function of time of sessile bubbles in water using the same surfactants and a protein.
- Measurements of surface elasticity by oscillation of sessile bubbles in water sing the same surfactants.
- Plotting of data and writing of lab report.