REORIENTATION OF POLYETHYLENE-GLYCOL OCTYLPHENYL ETHER IN NONEQUILIBRIUM ADSORPTION LAYERS AT THE WATER/AIR INTERFACE - ROLE OF MOLECULAR-WEIGHT AND TEMPERATURE

The dynamic surface tensions of aqueous Triton X solutions (X-45, X-100, X-114, X-165, X-305, and X-405) were measured by using a maximum bubble pressure technique in a broad concentration and temperature interval. Using a special measuring cell for the MPT1/LAUDA, studies in the time interval from 100 mu s up to 50 s were achieved. The results at very short adsorption times simulate a faster surface tension decrease than expected from a common diffusion-controlled mechanism. The deviation from that theory increases with temperature and the length of the ethylene oxide chains. The experimental results are in agreement with a theoretical model taking into consideration different orientations of the EO chain in diluted and compressed adsorption layers and the temperature effect on the interfacial water structure.