Adsorption behavior of alternating copolymers with hydrophobic and hydrophilic side chains: An ESR study of the spin-labeled polymers

The conformationt double dagger of the polymers poly(1-octadecene-alt-maleic anhydride) (PODMA, 1) and poly(1-dodecene-alt-maleic acid mono{2-[2-[2-[2-[2- [2-(2-methoxyethoxy)ethoxy]ethoxy]ethoxy]ethoxy]ethoxy]ethyl} ester) (PDDMAM(EO)(7)Me, 2) adsorbed on Aerosil 200 was evaluated by means of ESR spectroscopy. The fraction of the polymer segments in ''trains'', ''short loops'', and ''tails''/''long loops'' was determined as a function of the degree of surface coverage Theta according to a modification of the method of Sakai et al. The theory of Scheutjens and Fleer fits the experimental results obtained for PODMA very well; the theory fails, however, to predict the experimental results obtained for PDDMAM(EO)(7)Me. As a consequence the description of the conformation of PDDMAM(EO)(7)Me in the adsorbed state cannot be described by the present method. The differences in the adsorption behavior of PODMA and PDDMAM(EO)(7)Me are explained in terms of structural features of the polymers. Interactions of the heptakis(ethylene oxide) side chains of PDDMAM(EO)(7)Me in the adsorbed state lead to a substantial fraction of segments in ''trains'' even at high surface coverages.