POLYMERS AT SOLID INTERFACES - A SPIN-LABELING APPROACH

Polymers physically adsorbed or chemically grafted on a solid surface can be studied at a microscopic molecular level by Electron Paramagnetic Resonance (EPR) spectroscopy. The signal of nitroxide free radicals used as spin labels is sensitive to the Brownian motion of the segments and generally shows lines characteristic of two different environments, the loops and tails in solution, and the trains on the surface. The previsions of simple models for what can be expected from the measurements are recalled. The relevance of the method is confirmed on linear neutral chains in well defined situations. The technique is then applied to a number of new systems giving valuable information on the behaviour of the macromolecules in these more complex conditions.