Ramé-Hart Goniometer Contact angle goniometry measures the angle formed between a liquid and a solid suface, and determines the wettability of that surface.
Our Rame-Hart goniometer is equipped with a microsyringe for rapid and precise drop formation.
BELOW: Droplets formed on silicon and poly(tetrafluoroethylene) show the difference in wettability of the two surfaces.
Contact angle goniometry can be used to follow surface reactions. Here the photodegradation of poly(ethylene terephthalate) was monitored over time.
Contact angles decreased from 76° to 47° over a 100 min time period, suggesting that the surface had become more hydrophilic. Further photodegradation caused a build up of low molecular weight material at the surface reducing the contact angle further (black line). This material was removed by washing the samples in ethanol (red line).
The level of agreement between data obtained on the macro and microscale is illustrated by comparison with the friction coefficient of each surface. A linear dependence was observed indicating the data were in agreement.