Displacement of poly(ethylene oxide) adsorbed on silica by a nonionic surfactant studied by spin labeling

Poly(ethylene oxide) chains labeled at one end by a nitroxide free radical were adsorbed on silica. The electron paramagnetic resonance spectrum is mainly sensitive to the local Brownian motion and shows lines typical of two different environments, namely, loops and tails protruding in solution with a fast motion, and trains adsorbed on the solid with a hindered motion. When a solution of nonionic Triton surfactant with different concentrations is put in contact with the coated surface, the polymer segments are progressively removed from the surface and the chains extend into solution. This displacement is recorded as a function of temperature and concentration and follows a well‐defined smooth path.