RESUMO
The stability of thin wetting films formed from 0.15 M NaCl solutions containing small unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles of different concentrations on quartz surface has been investigated by the microinterferometric method. The intensity of monochromatic light reflected from both film surfaces has been recorded as a function of the time of film thinning. Two temperatures were used in the experiments (20 and 35 degrees C). Films containing 10(-3), 5x10(-3) and 10(-2) mg/ml DMPC were unstable and ruptured, while films with 10(-1) and 1 mg/ml DMPC were stable. Film stability was explained on the basis of hydrophobic interactions. Film thickness dependence on time was calculated. The kinetics of film thinning did not obey Reynolds equation and a linearization was observed in co-ordinates ln(h) as a function of time. This phenomenon was explained by a non-homogeneous thinning process, which might be due to the existence of some areas of different structure of the DMPC adsorption layers.
