Columnar liquid crystals (LCs) are reported to align spontaneously homeotropically—that is, orthogonally to the surface (see figure and inside cover)—on a glass surface covered with a layer of poly(tetrafluoroethylene) transferred by friction (rubbing). This strategy for producing macroscopic monodomains of homeotropically aligned LCs may find important applications in the fabrication of LC‐based organic solar cells.

Four newly synthesized alkoxy tetrasubstituted phthalocyanines (Pcs) were characterized by polarized optical microscopy, differential scanning calorimetry, and X-ray diffraction on oriented samples. It was found that the introduction of lateral alkyl chains branched in the second position renders the material liquid crystalline at room temperature. The studied Pcs exhibit a transition between a columnar hexagonal and a columnar rectangular phase. The tilt of the molecules with respect to the columnar axis in the rectangular phase, as measured by X-ray fiber diffraction, was found to be 15−18°. The columnar structure, and defects therein, in relatively thick spin-coated mesomorphic Pc films were for the first time characterized by tapping mode atomic force microscopy, employing ultra-sharp tips with nanometer-thick whiskers. Spin-coated films reveal layerlike structure with domain boundaries that can induce significant columnar curvature without breaking of the columns. In some instances, the boundaries delimiting different LC domains completely disrupt the columnar structure making the columns in neighboring regions uncorrelated.

The crystalline structure and semicrystalline morphology of poly(di-n-propyl siloxane), PDPS, were studied with powder and fiber X-ray diffraction, differential scanning calorimetry, solid-state nuclear magnetic resonance and atomic force microscopy (AFM). PDPS exhibits two crystalline phases, α (−45.5 °C < T < 62 °C) and β (T < −45.5 °C), and a hexagonal columnar mesophase which is stable in a broad temperature range between 62 and 197 °C. The low-temperature crystalline phase β is found to be monoclinic with lattice parameters a = 20.60 Å, b = 19.22 Å, c = 4.95 Å, γ = 93.1°. The α crystalline phase has a pseudo-tetragonal unit cell with a = b = 19.15 Å and c = 5.00 Å and is characterized by monoclinic C2/c (No. 15) group symmetry. In the refined unit cell (R wp = 0.127) the PDPS chains adopt a planar cis−trans conformation with the plane of the chain parallel to the b axis. The semicrystalline morphology of the α crystal was studied with AFM. The crystallization of PDPS from the hexagonal mesophase results in very thick (100−150 nm thick) crystalline lamellae, which implies that the chains are fully extended in the crystal. This feature, which is found in few polymers, makes PDPS similar to such systems as HDPE at high pressure or 1,4-trans-poly(butadiene).