Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Nematic fluids with polar order could be most useful new molecular materials. However, such ferroelectric liquid crystals have not been observed as yet. This paper describes the first computer simulations of a ferroelectric nematic phase made from simple tapered particles as shown in the picture and gives some hints a…
The controlled synthesis of nematic nanophase-separated materials poses an attractive synthetic challenge. The use of carbosilazane multipodes and dendrimers (such as 1) in conjunction with laterally attached mesogens allows the systematic investigation of the structure-property relationships of room-temperature nemat…
Incorporation of three metal ions (Ni or Cu) in the macrocyclic ring and the formation of hexamers following a 3+3 approach are novel features of the hemiporphyrazines (one example shown) formed by the condensation of 2,5-diamino-1,3,4-triazole with isoindolediimines. This is in contrast to the corresponding reactions…
Conducting polymer actuators generate forces that exceed those of mammalian skeletal muscle by up to two orders of magnitude for a given cross-sectional area, require only a few volts to operate, and are low in cost. However application of conducting polymer actuators is hampered by the lack of a full description of t…
A major aim for the chemical technology of the future is the avoidance of noxious and environmentally unacceptable organic solvents. In this concept article we discuss more environmentally friendly and highly selective alternatives which we have evolved for carrying out a number of important chemical conversions. Thes…
Novel chiral macrocycles consisting of two rigid oligoarylene rods and two chiral spiroindane clips have been synthesized by condensation of spiroindane diols and CF3-activated alpha-omega-difluorooligoaryls. Since a broad variety of planar aromatic macrocycles is known, our non-planar, chiral rings represent a new cl…
A multiple slip dislocation-density based crystalline formulation has been coupled to a kinematically based scheme that accounts for grain-boundary (GB) interfacial interactions with dislocation densities. Specialized finite-element formulations have been used to gain detailed understanding of the initiation and evolu…
Abstract It has been demonstrated that surfaces coated with poly(ethylene glycol) (PEG) are capable of reducing protein adsorption, bacterial attachment, and biofilm formation. In this communication cold‐plasma–enhanced processes were employed for the deposition of PEG‐like structures onto stainless steel surfaces. St…
Abstract The copolyester poly(ethylene glycol‐ co ‐cyclohexane‐1,4‐dimethanol terephthalate) (PETG) is used industrially as an uncrystallizable polymer, whereas PET is an inherently crystallizable polymer. Nevertheless, a crystalline phase could appear in the material. To create a strain‐induced crystalline phase in a…
The electrical conductivities and Seebeck coefficients of boron carbides ${\mathrm{B}}_{12+x}{\mathrm{C}}_{3\ensuremath{-}x}$ with $0.06\ensuremath{\lesssim}x\ensuremath{\lesssim}1.7$ have been measured from 8 K to as high as 1750 K. At high temperature, the temperature dependence of the conductivities is Arrhenius an…
The synthesis of a linear polymer that includes both P=N and P=S double bonds, and P-O and P-C single bonds is reported by using two different paths that involve deprotection reactions and the Staudinger reaction. The preparation of hyperbranched polymers made up of OC6H4P(Ph)2=N-P=S repeating units is also described.…
Unusual morphological features of boron nitride nanotubes produced via metal–oxide-promoted high-temperature syntheses from carbon nanotubes, boron oxide, and nitrogen were observed using high-resolution transmission electron microscopy. The tubes normally displayed open ends and preferentially two or four tubular lay…
The architecture of windmill hexameric zinc(II) -porphyrin array 1 is attractive as a light-harvesting functional unit in view of its three-dimensionally extended geometry that is favorable for a large cross-section of incident light as well as for a suitable energy gradient from the peripheral porphyrins to the meso-…
We report the results of an investigation carried on Methyl Red-doped nematic liquid crystals with the aim of studying the basic mechanism of the extraordinarily large nonlinear response recently reported. We show that the experimental data can be explained as due to light-induced modifications of the anchoring condit…
The field strength of the axial ligands determines the spin state of saddled iron(III) porphyrin complexes. Strong axial ligands (L), such as imidazole and 4-dimethylaminopyridine, lead to the formation of complexes with a pure S=1/2 state, while weak ligands, such as THF, give complexes with a pure S=3/2 state. Inter…
Hydrogen-bonding interactions between a benzotri(imidazole) derivative and a polymerizable alkoxybenzoic acid result in the formation of a supramolecular hexagonal columnar liquid crystal. Light-induced polymerization followed by removal of the benzotri(imidazole) core produces a porous polymer with hexagonal channels.
Extreme reaction conditions lead to the synthesis of γ-P3N5. Its crystal structure (see picture), unlike that of the normal pressure modification α-P3N5, is not exclusively built from PN4 tetrahedra, but from both PN4 tetrahedra (blue) and tetragonal PN5 pyramids (red). A tetragonal PN5 pyramid structure element has n…
A series of hydrosoluble dendrimers has been synthesized by capping phosphorus-containing dendrimers with hydrophilic end groups. These dendrimers form aqueous rigid gels at very low concentration (ca. 1.5 % per weight; see picture), which allows, for example, confinement of acids or metals. The structure of the gels…
Wenn ich erklären soll, welche Bedeutung die Entdeckung leitfähiger Polymere hatte, so habe ich zwei einfache Antworten: Erstens gab es sie nicht (und konnte es sie nicht geben!) und zweitens verfügen sie über eine einzigartige Kombination von Eigenschaften, wie man sie bei keinem anderen bekannten Material findet. Di…
Increased hydrophobicity of well-defined polyoxometalate clusters is possible through complexation with cationic surfactants in a one-pot reaction. The clusters, of toroid and spherical shape and colloidal dimensions, then organized into ordered, supramolecular assemblies, as shown schematically, are similar to classi…