Materials Literature
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The model compound, N -phenyl-4-(9-anthracenylethynyl)phthalimide ( 3 ), was synthesized and the thermal curing behavior analyzed. These results were compared to the curing kinetics of similar model compounds N -phenyl-4-(1-naphthylethynyl)phthalimide ( 1 ) and N -phenyl-4-phenylethynylphthalimide ( 2 ). The cure rate…
We have developed a simple and mild method for the fluorination of polybutadiene based on the addition of perfluoroalkyl iodides (R f I) to carbon−carbon double bonds. Triethylborane (Et 3 B) was utilized to initiate this free radical addition to model polybutadiene (PBD) homopolymers and a polystyrene−polybutadiene b…
This paper reports on the influence of the structural properties of two cationic hydroxyethylecelluloses, polyquaternium-4 (PQ-4; 1.13-1.27% N) and polyquaternium-10 (PQ-10; 1.88-1.95% N), on the rheological behavior of their dispersions and of the dispersions of their blends with Carbopol 974P (60.9% COOH) in water.…
Decaoxyethylene cetyl ether [C 16 (EO) 10 ] has been employed as templating agent for large pore disordered MSU-type mesoporous silicas synthesis. The effect of the hydrothermal treatment (heating time and temperature) on the textural properties, in particular, pore diameter of materials has been investigated. The obt…
The intrinsic viscosity of narrow molecular mass distribution polystyrene standards, poly(benzyl) ether dendrimers, and their hybrid block copolymers was measured in a variety of solvents. The relative change in the intrinsic viscosity for all these polymers was almost equivalent, indicating that poly(benzyl ether) de…
We have proposed an easy method for growth of well-aligned patterned CNTs arrays using 3D cubic ordered mesoporous silica films as the catalyst support combined with the soft-lithography technique. This synthetic approach shows fascinating possibilities for directed growth of CNTs that could be used for large-area, lo…
This paper presents a continuation of our earlier research on the crystallization and solid-state structure of polylactide copolymers. The focus here is on random copolymers containing predominately l -lactide and small amounts (1.5, 3, and 6%) of d -lactide. As expected, degrees of crystallinity and spherulite growth…
Byssal threads provide marine mussels with the tenacity to remain sessile in habitats of high flow. Under uniaxial tension, byssal threads are typical of other biological and synthetic fibers in exhibiting an initial linear region followed by yield. They differ, however, in their capacity to recover or "self-heal" fol…
Study on the molecular packing of the α-form of poly( l -lactide) has been attempted taking into account packing energy calculations, refinement against new electron diffraction data, and Monte Carlo simulations. Packing energy has been evaluated for a fixed 10 7 conformation and an antiparallel arrangement of molecul…
Using the spin-polarized tunneling model and taking into account the basic physics of ferromagnetic semiconductors, we study the temperature dependence of the tunneling magnetoresistance (TMR) in the diluted magnetic semiconductor (DMS) trilayer heterostructure system (Ga,Mn)As/AlAs/(Ga,Mn)As. The experimentally obser…
We present a class of discrete Schrödinger operators, with potentials derived from nonprimitive substitutions, that has purely singular continuous spectrum. We give sufficient conditions on the substitution rule assuring singular continuous spectrum, either for a generic set in the hull of the potential or for a set o…
Abstract A low molecular weight prepolymer with reactive end groups was annealed at temperatures between 200 and 245°C to obtain kinetic parameters for solid‐state polymerization of poly(ethylene naphthalate) (PEN). An equation was developed to describe the relationships among time, temperature, and final molecular we…
When a liquid sheet is subject to vertical vibration, parametric instabilities may occur and give rise to standing waves. The present work develops the linear theory of this phenomenon for inviscid, Newtonian and viscoelastic liquids. Floquet theory is applied to the governing equations to obtain recursion relations f…
Abstract The graft copolymerization of N ‐vinyl pyrrolidone ( N ‐VP) onto cellulose was carried out with a cobalt acetylacetonate complex Co(acac) 3 as an initiator under a nitrogen atmosphere at 50 ± 0.1°C. The graft yield percentage (% G ) obtained as a function of the concentrations of N ‐VP and Co(acac) 3 and the…
Abstract N ‐hexenyl side branches were introduced into poly(butylene succinate) (PBS) by polymerization of succinic acid (SA) with 1,4‐butanediol (BD) in the presence of 7‐octene‐1,2‐diol (OD). Thermal properties and biodegradability of the aliphatic polyesters were investigated before and after epoxidation of the pen…
As a model of the core of molecules forming liquid crystals, the molecular structure of phenyl benzoate (Ph-C(=O)-O-Ph) at 409 K was determined by gas electron diffraction, and the relationship between the gas-phase structures of model compounds and the nematic-to-liquid transition temperatures was studied. Structural…
Abstract Regenerated Antheraea pernyi silk fibroin films prepared from calcium nitrate solution were treated with heat for crystallization. The structural and conformational changes caused by heat treatment were investigated with X‐ray diffraction, infrared spectroscopy, and differential scanning calorimetry. The temp…
Abstract Poly(β‐hydroxybutyrate) (PHB) is a bacteria storage biodegradable polyester that is considered to be a natural substitute for synthetic thermoplastics in many applications. However, brittleness hampers its utility. This study shows that oriented elastic fibers of PHB with favorable mechanical properties (360‐…
The synthesis, structure, and physical characterization of two new radical salts formed with the organic donor bis(ethylenethia)tetrathiafulvalene (BET-TTF) and the octahedral anions hexacyanoferrate(III), [Fe(CN)(6)](3-), and nitroprusside, [Fe(CN)(5)NO](2-), are reported. These salts are (BET-TTF)(4)(NEt(4))(2)[Fe(C…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTOne-Electron Reduction of an Antiferromagnetically Coupled Triradical Yields a Mixed-Valent Biradical with Enhanced Ferromagnetic CouplingDavid A. Shultz and R. Krishna KumarView Author Information Department of Chemistry North Carolina State University Raleigh, North…