| 초록 |
Although most works on the liquid crystalline polymers were concerned with bulk materials, less work was done on the thin films of such materials. In this work, order and surface properties are investigated with side chain liquid crystalline polymer, poly(oxyethylene) containing n-heptylsulfonylmethyl side chains. X-ray reflectivity results revealed that the spin-coated films on silicon wafer have lamellar ordering upon annealing above the glass transition temperature, and the ordered layers are parallel to the substrate surface. The layer thickness is roughly twice the fully extended side-chain length, indicating a double-layered structure with side chains normal to the polymer backbone having all-trans conformation. Glass transition and a smectic-to-isotropic transition are observed from DSC, POM and XRD. The holes/or island appears in the top layer from the atomic force microscopic observation. The surface energy of the coated films was changed abruptly at the transition temperature. From AFM observation and NEXAFS spectroscopy, this can be interpreted that the packing of the CH3 groups at the surface causes the low surface energy due to the regular arrangement of the side chains in the top layer, which is disordered at the transition temperature because the poly(oxyethylene) backbone and side chains favor coiling with increasing temperature. A remarkable change in tack properties was observed at the transition temperature. |
