SURFACE ORIENTATION OF LIQUID-CRYSTALLINE POLY(ALKYLSILANES)

X-ray diffraction measurements on thin films of poly(hexyl-pentylsilan e) cast on silicon substrates are presented. The polymer chains pack i n a hexagonal lattice which is oriented such that the chains lie paral lel to the surface. In addition, a remarkable degree of orientational order was found with the planes containing the neighbor molecules lyin g in the surface plane. Parallel to the film surface, the average crys talline size is 600 angstrom, while perpendicular to the surface, ther e is nearly perfect interchain stacking of the polymers throughout the thickness of the film.