Unique morphology of poly(azomethine ethers) sheared in the liquid crystalline state

Abstract

The morphology and electron diffraction patterns of sheared films of a series of aliphatic-aromatic poly(azomethine ethers) with n = 1,4 and 7–10 CH₂ units in the aliphatic segment have been characterized by transmission electron microscopy. The films were prepared by shearing in the liquid crystalline (nematic) state. In all cases, lamellae ca. 400 Å thick and more or less perpendicular to the shear direction and perpendicular to the substrate were obtained. Annealing increases the lamellar thickness and overall order. Redrawing of annealed, sheared samples of n = 10 suggests they consist of chain folded lamellae. Electron diffraction (ED) yielded h0l single crystal patterns in all cases, except for n = 1, which yielded orthorhombic, fiber-like patterns. The h0l patterns suggest a planar, single crystal orientation over the entire sample. Annealing sheared samples above the crystal-liquid crystal transition temperature resulted in reorientation of the molecules (from parallel to perpendicular) with respect to the substrate. ED patterns changed accordingly from h0l to hk0. Sheared samples with n = 4 gave both orthorhombic and monoclinic diffraction patterns.