Surface-induced ordering of an aromatic polyimide

Grazing incidence x-ray diffraction has been used to characterize the near surface structure of an aromatic polyimide film. It is shown that within the first 90 from the surface the ordering of the polymer molecules is markedly enhanced. As the penetration depth of the x rays decreases, reflections characteristic of density correlations along the polymer chain axis shift to smaller scattering vectors and those indicative of intermolecular ordering become clearly evident. Thus, near the surface essentially crystalline order is seen. © 1991 The American Physical Society.