Directing supramolecular nanoparticle binding onto polymer films: Film formation and influence of receptor density on binding densities

We report on the deposition of nanoparticles onto polymeric surfaces by use of a multiple hydrogen bonding interaction. Main interest concerned the preparation of statistical copolymers with a defined number of interactions within the side chain, thus enabling control of the number of supramolecular interactions present on the surface for the subsequent binding-process. Thus, statistical copolymers of poly(oxy)norbornenes bearing either perfluorinated side chains or the "Hamilton receptor" in amounts ranging from 1 to 70 mol % were prepared using a ROMP methodology combined with subsequent azide/alkine "click" reactions. Films cast from these polymers-either via spin- or via dip-coatings were used to study the binding of barbituric acid-functionalized Au nanoparticles (diameter = 5 nm) bearing the matching supramolecular interaction toward the Hamilton receptor on the polymeric surface. A detailed AFM analysis of the films was performed, detailing the influence of film-casting conditions on the properties of the final polymeric films. A strong effect on the bound density of the NP's was observed only at lower concentrations (below 1 mol %) of the supramolecular receptor, whereas higher amounts of receptor units exhibit only minor effects on the density of bound nanoparticles. Thus, the presented method offers the generation of polymeric films with a defined density of nanoparticles bound to their surfaces.