LOCAL UNIAXIAL ORDER IN A GRAFTED POLYMER MELT VIA DEUTERIUM NMR

Dynamics of end-grafted polymer chains on a solid substrate are invest igated by deuterium NMR, which is sensitive to the anisotropy of molec ular motions. The experiments are performed on a perdeuterated polydim ethylsiloxane melt grafted on planar silica slides. The NMR spectra sh ow clearly that chain segments undergo uniaxial reorientations around the normal to the interface. This local order reveals the existence of orientational correlations between chain segments. The corresponding degree of anisotropy is much higher than in other lamellar systems suc h as block copolymers.