Polymer-organosilane interactions studied at the air/water interface

Mixed monolayers of octadecyltrimethoxisilane, OTMS, and poly(ethylene oxid e), PEG, have been studied at the air/water interface as a function of pH b y means of surface pressure and surface potential isotherms. PEO had a stro ng influence on the isotherms at large monolayer areas, while it was squeez ed out of the air/water interface at high surface pressures. The LE-LC tran sition pressure of unhydrolyzed OTMS was increased by several mN/m in the p resence of PEG, while PEO had little influence on the isotherms of hydrolyz ed OTMS at small monolayer areas. The results are discussed in terms of att ractive van der Waals interactions between methoxy groups of nonhydrolyzed OTMS and PEO.