Molecular-weight effects of a homopolymer on the AB- and ABC-stacks of perforations in block copolymer/homopolymer films.

We have demonstrated the molecular-weight effects of adding homopolystyrene (hPS) on the evolution of perforated layers and double gyroids in polystyrene-block-poly(methyl methacrylate)-based films during isothermal annealing. Two homopolystyrenes of 2.8 and 17 kg mol-1 were used. To prepare blend films, PS-b-PMMA and hPSx (x: 2.8 or 17) were mixed at a weight-fraction ratio of 75/25 in toluene and then spin-coated at SiOx/Si. Spin coating inevitably produced films with thick edges at the periphery of the substrate. The structural evolution of the spun films was in situ characterized by grazing incidence small-angle X-ray scattering (GISAXS). The annealed films were then characterized using a scanning electron microscope (SEM). We found that thin middle regions behaved differently from thick beads for the films. The middle of the blend films mainly formed perforated layers with different spatial orders and orientations, depending on the molecular weight of added hPS chains. Hexagonally perforated layers quickly formed at 205 °C for PS-b-PMMA/hPS2.8 films. However, when hPS17 was used instead of hPS2.8, perforated layers formed with defects in PS-b-PMMA/hPS17 films annealed at 205 °C. Annealing at 240 °C improved the spatial order and orientation of perforated layers for a PS-b-PMMA/hPS17 film. Nevertheless, annealing at 240 °C inversely depressed the in-plane spatial order of perforated layers for a PS-b-PMMA/hPS2.8 film. The depression in the in-plane spatial order is ascribed to a dilution effect of added short chains. Compared to the middle regions, the thick beads went through several metastable phases, such as perpendicularly oriented perforated layers and double gyroids.

Poly[bis-(µ(2)-4,4'-bipyridine)bis-(3-nitro-benzoato)cobalt(II)].

The hydro-thermal reaction of cobalt nitrate with 4,4'-bipyridine and 3-nitro-benzoic acid lead to the formation of the title complex, [Co(C(7)H(4)NO(4))(2)(C(10)H(8)N(2))(2)](n). In the crystal structure, the Co(II) atoms are coordinated by two terminal carboxyl-ate anions and four 4,4'-bipyridine ligands within slightly distorted octa-hedra. The Co(II) atom and one of the two independent 4,4'-bipyridine ligands are located on a twofold rotation axis, while the second independent 4,4'-bipyridine mol-ecule is located on a centre of inversion. One of the two rings of one 4,4'-bipyridine ligand is disordered over two orientations and was refined using a split model [occupancy ratio 0.68 (2):0.32 (2)]. The Co(II) atoms are connected by the 4,4'-bipyridine ligands into layers, which are located parallel to the ab plane.

catena-Poly[[tetraaquanickel(II)]-µ(3)-benzene-1,3,5-tricarboxylato-3':1:2-κO:O,O:O-[tetraaquanickel(II)]-µ(2)-benzene-1,3,5-tricarboxylato-2:3κO:O-[tetraaquanickel(II)]].

The microwave solvothermal reaction of nickel nitrate with trimesic acid provided the title compound, [Ni(3)(BTC)(2)(H(2)O)(12)](n) (BTC = benzene-1,3,5-tricarboxyl-ate anion, C(9)H(3)O(6)), which is a metal coordination polymer composed of one-dimensional zigzag chains. The crystal under investigation was ramecically twinned with an approximate twin domain ratio of 1:1. In the asymmetric unit, there are two types of Ni atoms. One of the NiO(6) groups (2 symmetry) is coordinated to only one carboxyl-ate group and thus terminal, the other is bridging, forming the coordination polymer. The extended chains are connected by the organic BTC anions via µ(2)-linkages. O-H⋯O hydrogen bonds and π-π inter-actions between the chains [centroid-centroid distance 3.58 (1) Å] induce the complex to mimic a three-dimensional structure.