Dynamic x-ray diffraction studies of liquid-crystalline polyesters

Mesophase transitions in liquid-crystalline (LC) polyesters were studied by dynamic x-ray diffraction using a synchrotron radiation source. Powder and fiber samples were examined by continuous heating from 50°C to 270°C in a hot stage. The polymer systems consisted of two types of thermotropic polyesters with mesogenic cores composed of combinations of substituted terephthalate, oxybenzoate and hydroquinone units combined with aliphatic spacers placed in the main chain. One of these samples was a chemically homogeneous LC polyester (HTH12) while the other LC polyester possessed chemical heterogeneity (BP6). BP6 could also be processed to form fibers which showed thermal transition behavior by x-ray diffraction and no detectable melting or clearing transition by thermal measurements. LC textures were observed using polarized light microscopy. Results of the dynamic x-ray diffraction studies of these two LC polymers are described.     

Visible-Light Responsive Cu–MOF–NH2 for Highly Efficient Aerobic Photocatalytic Oxidation of Benzyl Alcohol

Kinetics and Catalysis - The current study focuses on the photocatalytic oxidation of benzyl alcohol in acetonitrile under air bubbling conditions comparing titania-based materials, Cu–MOF,...