[en] Highlights: • The non-covalent modification of graphene maintains the intrinsic structure of graphene compared with the covalent functionalization of graphene. • The initial degradation temperature of nanocomposite film increases by 57 °C which is much higher than that of PUA nanocomposite previously reported. • The nanocomposite film exhibits improved dielectric property and electrical conductivity. • The outstanding performance of CTAB-G/PUA films will open up enormous opportunities for applications in various regions such as high temperature or electrical field. - Abstract: The preparation of nanocomposite films composed of UV-curable polyurethane acrylate (PUA) and modified graphene were demonstrated in this paper. Cetyl trimethyl ammonium bromide modified graphene (CTAB-G) was prepared via intercalation of cationic surfactant and subsequently incorporated into PUA by UV curing technology. Fourier transform infrared spectra, wide-angle X-ray diffraction, scanning electron microscopy and transmission electron microscopy were used to characterize the structure and morphology of CTAB-G, as well as CTAB-G/PUA nanocomposite films. The results revealed that the CTAB-G sheets were layer-by-layer structure and dispersed uniformly in PUA matrix. Thermal gravimetric analysis showed that the thermal stabilities of UV-curable PUA nanocomposite films in this work were much higher than that of PUA nanocomposites previously reported. Dynamic mechanical analysis indicated that the dynamic mechanical properties of nanocomposite films were greatly enhanced in the presence of modified graphene sheets. In addition, the CTAB-G/PUA nanocomposite films exhibited improved dielectric properties and electrical conductivities compared with the pure PUA.

[en] We have grown underdoped (x = 0.11, 0.12) and optimally doped (x = 0.16) La_2–xSr_xCuO₄ single crystals by the traveling-solvent floating-zone technique. In order to prepare good quality cuprate crystals, we have made much effort to optimize the preparation procedures. For example, we haveadopted the sol–gel route to prepare a highly fine and homogeneous La_2–xSr_xCuO₄ precursor powder for fabricating a very dense ceramic feed rod used for the floating-zone growth, and we have also used quite a slow growth rate. The high quality of the grown crystals has been verified by double-crystal x-ray rocking curves, with the full-width-at-half-maximum being only 113–150 arcseconds, which are the best data reported so far for La_2–xSr_xCuO₄ crystals. The superconducting critical temperatures of the grown crystals are 30, 31 and 38.5 K for x = 0.11, 0.12 and 0.16 samples, respectively, according to magnetic measurements. (condensed matter: structure, thermal and mechanical properties)