Development of a new Langmuir-type pendant-drop film balance

Development of a Constant Surface Pressure Penetration Langmuir Balance Based on Axisymmetric Drop Shape Analysis

“…The functionality of our device as film and penetration balance at liquid-air and liquid-liquid interfaces has already been shown (16,18,19). Several computer simulations and experiments were done to develop and tune the elements of the fuzzy control: rule base, the membership functions of the fuzzy sets, and the inference mechanism.…”

“…For studies with insoluble monolayers, the latter is formed by spreading onto the drop surface, i.e., by deposition of a surfactant solution using a Hamilton (1 µl) microsyringe placed on a micropositioner, as previously described (16).…”

“…We chose the above-mentioned no-load situations, i.e., for the area control a pure water drop, and for the pressure control a monolayer on water subphase, spreading 75 pmol DMPC by deposition-on-drop as described in (16). In both cases a similar protocol was used: starting from some initial drop state, the device was programmed to bring the drop via step set-point change to a certain state, characterized by some value of the measurement variable, and to maintain it there during 30 measurementcontrol cycles.…”

“…ADSA was originally developed for determining the interfacial tension, contact angle, drop surface area, and drop volume based on a drop profile (7), and among other uses has been applied successfully to the measurement of interfacial tensions between immiscible liquids (9), and to the determination of ultralow interfacial tensions (10). It also has been employed for relaxation kinetics studies of surfactant adsorption layers (11)(12)(13)(14) and as a film balance at the air-water interface (15)(16), at the oil-water interface (17), and recently as a penetration film balance at the air-water interface (18) and at the oil-water interface (19), offering a wide range of possibilities and advantages over conventional surface balances.…”

Measurement of Dynamic Surface Tension of Surfactant Solutions

“…Measurements of dynamic surface tension have been made by the pendant-drop method in many cases, and various factors affecting the dada by this method has been examined; change of the temperature and mass concentration in water solutions, 9) change of the drop shape, 10,11) influence of the adsorption and diffusion in a drop, 12,13) film balance of a new Langmuir-type, 14) stress relaxation behaviour on the surface, 15) formation of shear-thinning and yield stress in fluids. 16) However investigation on the viewpoint of dynamics has not been conducted thoroughly.…”