Surface structure and dynamics of supercooled polymer melts and metal-polymer nanocomposites [Elektronische Ressource] / Simone Streit

Surface structure and dynamics ofsupercooled polymer melts andmetal-polymer nanocompositesSimone StreitA thesis submitted to the Department of Physicsin fulflllment of the requirements for the degree ofDoctor of Natural SciencesFachbereich PhysikUniversit˜at DortmundMay 2007AbstractThe focus of this work is the investigation of the surface properties of supercooledliquids and metal-polymer nanocomposites around the glass transition temperature TGat nanometer length scales. This thesis provides two major contributions in the fleldof surface sensitive x-ray scattering techniques employed to characterize the behavior ofsurface uctuations in polymeric liquids around T and the nanoparticle dynamics inGout-of-equilibrium systems.The research topic of the flrst part of this thesis consists in the determination of thecoolingratedependentfreezingofcapillarywavesontheglassformingliquidpoly(propy-lene glycol) by means of in-situ cooling x-ray re ectivity measurements. The freezingin of density uctuations while approaching the glass transition has been known in thebulk for a long time, but it has not been determined until now whether an analogousefiectalsooccursatthefreesurface. Above T thesurfaceroughness? canbedescribedGbythestandardcapillarywavemodelforsimpleliquids,whereasthesurface uctuationsare frozen in at temperatures below T .