The behavior of II-A isotherm with increasing amount of calix[4] arene at air–water interface

The surface pressure-mean molecular area (П-A) isotherm of surfactant (Mat 7) was obtained by using Langmuir-Blodgett technique. The characterization of Mat 7 Langmuir film was carried out in terms of П-A isotherm. The Langmuir monolayer was successfully formed by spreading the Mat 7 solution directly at air-water interface. The optimum condition such as the volume of surfactant loaded on the subphase was studied. It is observed that with increasing amount of Mat 7 on water surface, П-A isotherm shifted towards the left. The mean surface area occupied by each Mat 7 molecule was estimated by extrapolating the linear portion of each curve (between 10 and 20 mN/m) to a surface pressure equal to zero. The UV-Visible spectra of Mat 7 in chloroform showed a significant result. The absorption peak increased as more concentrated solution was added.