Materials Literature
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The self-diffusion properties of a poly(styrene- b -isoprene) diblock copolymer ( M PS = 10000, M PI = 13000) in a lamellar microstructure have been determined by forced Rayleigh scattering. Diffusion coefficients along the lamellar interface ( D par ) and through the layers ( D perp ) were resolved. The lamellae were…
The cuboctameric silsesquioxane silanol ( c -C 5 H 9 ) 7 Si 8 O 12 (OH) has been applied as a model support for silica-grafted olefin polymerization catalysts. Complexes of the type Cp‘‘[( c -C 5 H 9 ) 7 Si 8 O 13 ]TiX 2 (Cp‘‘ = 1,3-C 5 H 3 (SiMe 3 ) 2; X = Cl, CH 2 Ph) form active α-olefin polymerization catalysts.
The ground- and excited-state properties of a series of p -phenylene-linked porphyrin dimers have been examined using a variety of static and time-resolved spectroscopic techniques. The dimers consist of a zinc porphyrin and a free base (Fb) porphyrin (ZnFbΦ), two zinc porphyrins (Zn 2 Φ), or two Fb porphyrins (Fb 2 Φ…
A high resolution optical method was used to acquire contact angle−velocity data for hexadecane and octamethylcyclotetrasiloxane (OMCTS) advancing and receding on a smooth, virtually homogeneous fluorinated surface. The predictive abilities of the hydrodynamic, molecular−kinetic and combined molecular−hydrodynamic mod…
Raman microscopy was used to investigate microstructural properties of amorphous MoO 3 thin films that had been subjected to a photochromic (PC) or electrochromic (EC) process. The Raman spectra changed reversibly when the films went through PC or EC coloration and decoloration cycles. Different molybdenum bronzes wer…
Studies of the temperature dependence of spherulitic growth rates, in the context of the Lauritzen−Hoffman secondary nucleation theory, and investigations of the crystallization time and temperature dependence of the melting behavior, in the context of the nonlinear Hoffman−Weeks (HW) extrapolation, are reported for i…
The Hall resistivity rho_{xy} of a La_{2/3}(Ca,Pb)_{1/3}MnO_3 single crystal has been measured as a function of temperature and field. The overall behavior is similar to that observed previously in thin-films. At 5 K, rho_{xy} is positive and linear in field, indicating that the anomalous contribution $R_S$ is negligi…
Gold nanorods are prepared in aqueous solution by an electrochemical method and are shape controlled by using capping micelles as described by Yu et al. ( J. Phys. Chem. B 1997, 101 (34), 6661). Transmission electron microscopic (TEM) images are determined for these gold nanorods, taken from solutions heated to variou…
A new approach to second-order nonlinear optical (NLO) materials is reported, in which chirality and supramolecular organization play key roles. Langmuir-Blodgett films of a chiral helicene are composed of supramolecular arrays of the molecules. The chiral supramolecular organization makes the second-order NLO suscept…
A polycrystalline sample of a new phase in the Sr-Fe-Mn-O system has been prepared by standard solid-state techniques. Characterization at room temperature by X-ray diffraction, high-resolution electron microscopy, Mössbauer spectroscopy and neutron diffraction has led to it being described as a 15-layered, rhombohedr…
By using the field effect (through-space charge-dipole or dipole−dipole interactions), efficient ketone catalysts 7 and 10 were developed for in situ epoxidation of olefins with Oxone. With either ketone 7 (10−20 mol %) or 10 (5−10 mol %) as catalyst, epoxidation of various olefins (2 mmol scale) at room temperature w…
We present a quantitative comparison between extensive Monte Carlo simulations and self-consistent field calculations on the phase diagram and wetting behavior of a symmetric, binary (AB) polymer blend confined into a film. The flat walls attract one component via a short-range interaction. The repulsion between monom…
α-RuCl3 is a new host for polymer intercalation using an in situ redox intercalative polymerization recaction. With the aid of ambient oxygen, aniline molecules get oxidatively polymerized by the Ru3+ centers of the inorganic host and enter the two-dimensional galleries. An electrically conductive lamellar nanocomposi…
Twenty-six poly(oxyethylene)-poly(oxybutylene) diblock copolymers were prepared by anionic polymerization. The phase behavior of these copolymers was studied near the order−disorder transition over the composition range from 0.21 to 0.84 poly(oxyethylene) volume fraction. Small-angle X-ray scattering was used to chara…
The sonolytic degradation of ozone (O 3 ) was investigated in both closed and open continuous-flow systems to examine effects of mass transfer on chemical reactivity in the presence of ultrasound. Degradation of O 3 followed apparent first-order kinetics at frequencies of both 20 and 500 kHz in all the systems. Degass…
The preparation, crystal structures, and variable temperature magnetic susceptibility data are presented for two azido-bridged Schiff base complexes of Mn(III) and Fe(III). Mn(salpn)N(3) (1), where salpn is the dianion of N,N'-bis(salicylidene)-1,3-diaminopropane, crystallizes in the orthorhombic system, space group P…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTInvestigation of Brill Transition in Nylon 6 and Nylon 6,6 by Infrared SpectroscopyNadarajah Vasanthan, N. Sanjeeva Murthy, and Robert G. BrayView Author Information Engineered Material Sector Laboratories, AlliedSignal Inc., Morris…
We study a scalar lattice model for inter-grain forces in static, non-cohesive, granular materials, obtaining two primary results. (i) The applied stress as a function of overall strain shows a power law dependence with a nontrivial exponent, which moreover varies with system geometry. (ii) Probability distributions f…
Powder X-ray diffraction (XRD), 29 Si magic-angle-spinning (MAS) NMR spectroscopy, and transmission electron microscopy (TEM) as well as N 2 adsorption have been employed to study the formation of various mesophases that lead to the synthesis of cubic mesoporous MCM-48 molecular sieve. A typical synthesis is performed…
Experimental solubilities are reported for anthracene dissolved in ternary 1-propanol + 1-butanol + 2,2,4-trimethylpentane, 1-propanol + 2-butanol + 2,2,4-trimethylpentane, 2-propanol + 1-butanol + 2,2,4-trimethylpentane, and 2-propanol + 2-butanol + 2,2,4-trimethylpentane solvent mixtures at 25 °C. Nineteen compositi…