Order in thin films of side-chain liquid-crystalline polymers.

Spin-coated side-chain liquid-crystalline polymer films, based on alternating copolymers of maleic anhydride and -olefins carrying terminal mesogenic methoxybiphenylyloxy groups, on silicon wafers show lamellar ordering upon annealing above the glass transition temperature. In the surface topography (atomic force microscopy measurements), structures are visible with a height corresponding to a bilayer. Also within the film, the side chains are ordered perpendicularly to the surface as measured by X-ray reflectometry. There are indications that directly at the substrate surface the side chains are aligned parallel to the surface. By the two complementary techniques, a rather complete picture is obtained. Even though the films are very thin (nanometer-scale thickness), the structure has a high degree of perfection and the bilayer spacing is the same as measured for bulk polymer