Surface and interfacial tensions are fundamental properties of liquid interfaces that determine functional outcomes in virtually any field that requires wetting, mixing, formulating, recovery, or distributing of liquids. It can also indicate the age and quality of liquid formulations, making it relevant for both liquid development and quality control. This specific measurement, using the pendant drop method, has many experimental advantages over classical force tensiometry techniques, such as using small liquid volumes and the ability to couple with dynamic conditions (interfacial rheology, high pressure, and high temperature). In a standard pendant drop measurement, a droplet is suspended from a needle tip while images of its silhouette are taken with an optical tensiometer and fitted with a drop shape analysis software. However, physical properties of the liquid, such as high volatility, extreme viscosity, and low surface tension, can make it challenging to practically implement. Similarly, measuring contact angles on hydrogels and hydrated materials can be virtually inaccessible with standard sessile drop methods.
In this masterclass, we will discuss how using a hooked needle with a transparent cuvette can simplify these measurements for challenging liquids and surfaces. We will introduce the inverted pendant drop method and go hands-on through setting up a measurement correctly with our Attension Theta Flow Optical tensiometer interfaced with a hook needle to measure surface and interfacial tension easily and accurately. Further, we will apply the hooked needle to perform a captive bubble measurement, an excellent tool for measuring the wettability of hydrated and otherwise high surface energy surfaces.
View the Entire Masterclass Series:
- Going Full-Tilt: Dynamic Contact Angle Measurements with a Tilting Cradle
- Measuring Roughness Corrected Contact Angle: Combined Contact Angle and Surface Roughness Measurements with 3D Topography
- It’s a Small World: Contact Angles at the Picoliter Scale
- Dynamic Contact Angle Measurements with a Tilting Stage
- Get Hooked: Interfacial Tenson & Captive Bubble Measurements with a Hooked Needle
- Dilatational Interfacial Rheology with the Pulsating Drop Module
