Synthesis and characterization of 2-(2-benzhydrylnaphthyliminomethyl)pyridylnickel halides: formation of branched polyethylene

A series of 2-(2-benzhydrylnaphthyliminomethyl)pyridine derivatives (L1–L3) was prepared and used to synthesize the corresponding bis-ligated nickel(II) halide complexes (Ni1–Ni6) in good yield. The molecular structures of representative complexes, namely the bromide Ni3 and the chloride complex Ni6, were confirmed by single crystal X-ray diffraction, and revealed a distorted octahedral geometry at nickel. Upon activation with either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all nickel complex pre-catalysts exhibited high activities (up to 2.02 × 10⁷ g(PE) mol⁻¹(Ni) h⁻¹) towards ethylene polymerization, producing branched polyethylene of low molecular weight and narrow polydispersity. The influence of the reaction parameters and the nature of the ligands on the catalytic behavior of the title nickel complexes were investigated

Nonlocal vibration of embedded double-layer graphene nanoribbons in in-phase and anti-phase modes

Graphene nanoribbons (GNRs), the finite-wide counterparts of crystalline graphene sheets, have been potential materials used in nano-devices because of their excellent electronic, thermal and mechanical properties. In this work, a theoretical analysis of nonlocal elasticity theory for the free vibrational characteristics of embedded double-layer GNRs (DLGNRs) is proposed based on continuum and Winkler spring models. We find two types of vibrational modes, in-phase mode (IPM) and anti-phase mode (APM). The results show that the vibrational properties of DLGNRs show different behaviors in IPM and APM. The natural frequencies of DLGNR embedded in an elastic matrix are significantly influenced by nonlocal effects, the aspect ratio of DLGNRs and the Winkler foundation modulus.ArticlePHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES. 44(7-8):1136-1141 (2012)journal articl

Nonlocal elasticity theory for the buckling of double-layer graphene nanoribbons based on a continuum model

The mechanical stability of graphene nanoribbons (GNRs) is an important mechanical property to study, when GNRs are used as components in sensors or other nanodevices. In this paper, nonlocal effects are considered in a continuum model based theoretical analysis of the critical buckling stress of cantilevered double-layer GNRs (DLGNRs) that are subjected to an axial compressive load. The results show that the nonlocal effect has an inverse relationship with the buckling stress, and the nonlocal effect decreases with increasing aspect ratio of DLGNRs. Moreover, to the best of our knowledge this is the first report that, for DLGNRs in anti-phase modes, lower buckling mode can endure higher buckling stress because of van der Waals (vdW) interaction.ArticleCOMPUTATIONAL MATERIALS SCIENCE. 50(11):3085-3090 (2011)journal articl

Radial breathing vibration of double-walled carbon nanotubes subjected to pressure

A theoretical vibrational analysis of the radial breathing mode (RBM) of double-walled carbon nanotubes (DWCNTs) subjected to pressure is presented based on an elastic continuum model. The results agree with reported experimental results obtained under different conditions. Frequencies of the RBM in DWCNTs subjected to increasing pressure depend strongly on circumferential wave numbers, but weakly on the aspect ratio and axial half-wave numbers. For the inner and outer tubes of DWCNTs, the frequency of the RBM increases obviously as the pressure increases under different conditions. The range of variation is smaller for the inner tube than the outer tube.ArticlePHYSICS LETTERS A. 375(24):2416-2421 (2011)journal articl