Chain segment order in ultrathin polymer films: a deuterium NMR study

The orientational order of monomerically thin films of polydimethylsiloxane melt deposited on the surfaces of cylindrical pores is investigated in this paper by solid-state deuterium nuclear magnetic resonance. Spectra demonstrate substantial orientation of the methyl groups by the surface. The quadrupolar splitting of the oriented film component saturates below one monomer layer, but decreases stepwise for thicker films. Comparisons of experimental and simulated spectra suggest a flat chain conformation in the first polymer monolayer.