In recent years, irreversibly adsorbed polymer layers formed on solid substrates have been received considerable interest since they can modify various properties of polymeric materials confined at the nanometer scale. In this thesis, I investigate the annealing time dependence of the poly (ethylene oxide) (PEO) adsorbed layer formed at the substrate interface. The detailed structures of the PEO adsorbed layer prepared were characterized by ellipsometry, atomic force microscopy (AFM), and x-ray reflectivity techniques. The total thickness of the PEO adsorbed layer is generally around 3 nm. Different from PS, the annealing time dependence of the PEO adsorbed layer simple show minor increase when annealing 2hr, then stay the same. ScCO2 and toluene rinse cycle can further reduce the thickness of PS adsorbed layer. For PEO, only toluene rinse is enough to obtain the final adsorbed layer. We discuss the model of the structure of the adsorbed layer, and estimate that there is no crystal structure formed in the PEO adsorbed layer.