End-tethered polymers

Date of Completion

January 1996


Chemistry, Polymer|Plastics Technology




The trend towards materials synergy and the growing use of plastic for weight and parts reduction places new importance on the performance of the interface between polymeric and non-polymeric components. Grafting a polymer molecule to the surface of a metal part, inorganic filler particle or reinforcing fiber can improve the wettability and adhesion of that surface. Thin polymeric films can also be used as surface coatings to tailor the lubricity, wettability or corrosion resistance over that of the native material. Important design variables include the thickness, morphology and molecular weight of the film as these influence the surface and interfacial properties.^ The process of thin-film growth and the interface between the thin film and matrix polymers is studied with several techniques. The adsorption of polymer from a binary solvent mixture is studied with a chromatographic technique using model polymers of varying molecular weight distributions. It was found that the solvent composition affects the thickness and morphology of the final film in a non-linear fashion and that the molecular weight distribution of the adsorbed polymer was found to change after a good solvent rinse. Study of the adsorption phenomenon with a model system in a binary solvent mixture shows that the observed film morphology and thickness non-linearity can be predicted by a random sequential adsorption model. The healing process and the composition profile at the interphase between tethered and matrix polymers is studied with specular neutron reflection. Computer modeling of the concentration profile in the interphase between a tethered polymer layer having a broad molecular weight distribution and a matrix polymer is carried out. The results show that both specific interactions between the two polymers and the molecular weight distribution of the adsorbed polymer affect the concentration profile. ^