Ellipsometrische charakterisierung der adsorptionsschichten von polyäthylenglycol, polyvinylpyrrolidon und polystyrol an chromoberflächen

Abstract

ZUSAMMENFASSUNG :In der vorliegenden Arbeit wurde die Adsorption von Polystyrol aus Cyclohexan (25 "C, 36 "C), Dioxan (15 "C, 36 "C) und Methylathylketon (15 "C, 36OC), die Adsorption von Polyathylenglycol aus Wasser und Methanol (25°C) und die Adsorption von Polyvinylpyrrolidon aus Wasser (25 "C) an hochvakuumbedampften Chromspiegeln mit Hilfe der Ellipsometrie untersucht . Aus den gemessenen Schichtdicken, Schichtkonzentrationen und adsorbierten Mengen ist zu folgern, da13 das polare Polyathylenglycol (PAG) in prinzipiell anderer Weise adsorbiert als das unpolare Polystyrol. PdG adsorbiert in flach auf liegender entkniiuelter Form, das unpolare Polystyrol dagegen in kniiuelformiger Konformation. SUMMARY :In the work presented, the adsorption of polystyrene (PS) from cyclohexane (25"C, 36"C), dioxane (15OC, 36°C) and methylethylketone (15"C, 36"C), the adsorption of polyethyleneglycol (PEG) from H2O and methanol (25°C) and the adsorption of polyvinylpyrrolidone from H2O ( 2 5 "C) was investigated by means of ellipsometry. Chrominium covered glass-slides, prepared by high-vacuum technic, were used as adsorbent. From the thickness, concentration and adsorbed amount measured it can be followed, that the polar PEG is adsorbed in a principle different manner than the unpolar PS. PEG prefers to adsorb in a flat uncoiled manner, while PS is adsorbed in a coil-form conformation.

The adsorption of macromolecules on solid/liquid interfaces

“…In contrast with the polymers discussed above (polystyrene and poly(methy1 methacrylate)), poly(ethy1ene glycol) adsorbs, on chrome surfaces [6], over the whole covera e range, assuming a flat expanded configuration with a thickness corresponds with the refractive index of pure solid polymer. Such data indicate that in the layer less than 20 A thick only pure polymer, without solvent, adsorbs.…”

“…This flat layer may be based 1) on the higher enthalpy of the hydrogen bond between the ether segments of poly(ethylene glycol) and the CrOH groups on the chrome surface, and 2) on an extended conformation of the poly(ethy1ene glycol) chain in solution (especially HzO). If the CrOH-groups were reacted chemically with dimethyldichlorsilane the CrOH-groups would be partially blocked, resulting in an increased thickness of the adsorbed layers; but the reproducibility is not very good [6].…”

Permeability study on adsorption phenomena of poly(vinyl acetate) in well defined porous media

“…4a+c for three concentrations. [4] ofvarious PVAC samples for 0,l (A) and 0,3 pm Millipore filters ( 0 ) ; conc. of polymer samples: 0,45 ( Fig.…”

The influence of the adsorbent amount on the changes in molecular mass distribution of polymers under adsorption from mixtures

“…The investigated polymers differ essentially in polarity. Their adsorbed macromolecules have different conformations: PBMA macromolecules are adsorbed in the extended conformation, PS macromolecules are adsorbed as coils [19].…”

“…In addition, the irreversibility of the PCL adsorption is explained by the strong interaction of the polymer end OH-groups with the active centers on the surface. Less polar polymer PVC is adsorbed as coils, with a smaller quantity of less strong bonds [19], and it facilitates the displacement of initially adsorbed low-molecular-mass fractions by the high-molecular-mass fractions during the establishing of adsorption equilibrium.…”