Materials Literature
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In this paper we describe polymers of two metallorotaxane systems, Rot( 1,M) and Rot( 2,M) (M = Zn 2+ or Cu 1+ ), which are formed by complexing a macrocyclic phenanthroline, a 5,5‘-bis([2,2‘-bithiophen]-5-yl)-2,2‘-bipyridine (ligand 1 ) or 5,5‘-bis(3,4:3‘,4‘-bis(ethylenedioxy)[2,2‘-bithiophen]-5-yl)-2,2‘-bipyridine (…
A specialized extracellular matrix of proteins and polysaccharides controls the morphology and packing of calcium carbonate crystals and becomes occluded within the mineralized composite during formation of the molluscan shell and pearl. We have cloned and characterized the cDNA coding for Lustrin A, a newly described…
The performance of any material in the human body is controlled by two sets of characteristics: biofunctionality and biocompatibility. With the wide range of materials available in the mid-1990s, it is relatively easy to satisfy the requirements for mechanical and physical functionality of implantable devices. Therefo…
The alignment and superposition of protein structures are sometimes complicated by the presence of insertions or deletions in one structure or the other. The program ALIGN [Satow, Cohen, Padlan & Davies (1986). J. Mol. Biol. 190, 593–604] was written to address this problem. The program provides information in its ana…
Abstract Lithium may constitute an essential element in micas, yet it cannot be detected by the electron microprobe. Since Li is critical for correctly classifying micas and properly calculating their formulae, several methods have been proposed to overcome this analytical deficiency. We offer empirical relationships…
Abstract Molecules adsorbed on evaporated thin metal films exhibit enormously strong infrared absorption. The thin metal films that exhibit the surface-enhanced infrared absorption (SEIRA) consist of metal particles much smaller than the wavelength of light. Electric field associated with the incident infrared radiati…
A mean-field, lattice-based model of polymer melt intercalation in organically-modified mica-type silicates (OLS) has been developed. In general, an interplay of entropic and energetic factors determines the outcome of polymer intercalation. Free energy curves and their dependence on energetic and entropic factors sug…
We report experiments on bilayer light emitting diodes made with organically capped CdSe(CdS) core/shell type semiconductor nanocrystals and an electroluminescent (EL) semiconducting polymer [poly(p-phenylenevinylene) or PPV]. The devices emit from red to green with external quantum efficiencies of up to 0.22% at brig…
The effect of silicate functionalization, anneal temperature, polymer molecular weight, and constituent interactions on polymer melt intercalation of a variety of styrene-derivative polymers in alkylammonium-functionalized silicates is examined. Hybrid formation requires an optimal interlayer structure for the organic…
A detailed study of the kinetics and mechanism of micromolecular transport in cellulose acetate films containing 2.0 acetate groups per glucose unit (CA-2.0) is reported. The polymer was prepared by controlled hydrolysis of CA-2.45 films studied in preceding articles. The same series of simple liquid penetrants varyin…
A novel GPC calculation method has been developed for characterizing star-shaped styrene–butadiene block copolymers (SBS). This method enables us to determine the degree of branching (number of arms per molecule) of the synthesized polymer without the need of a priori measurement of the true molecular weights of the S…
The mechanical properties of polypropylene depend critically on the crystallizability of the chains, which depends in turn on their stereochemical structures. These dependences were investigated using Monte Carlo methods to generate chains having various stereochemical sequences and then scrutinizing parallel arrays o…
The peroxide-initiated grafting of vinyltrimethoxysilane (VTMS) onto dodecane has been examined as a model for grafting onto polyethylene. At 160°C, 2% v/v VTMS and 0.08% v/v initiator, the monomer was grafted onto dodecane with a 59% conversion and an average of 2.37 VTMS grafts per dodecane. These values were obtain…
Tensile and impact properties of uncompatibilized nylon-6/ABS blends have been studied over the entire range of compositions. The blends were prepared by extrusion and, subsequently, injection molded into tensile specimens and rectangular plaques. The impact fracture performance was characterized using recently propos…
In situ Fourier transform infrared (FTIR) measurements were carried out to elucidate conformation changes occurring during the isothermal melt crystallization of poly(ethylene-2,6-naphthalate) (PEN). Based on the band assignments for the components of the amorphous, α-crystal form, and β-crystal form of PEN in film sa…
The morphology of homogeneous copolymers of ethene and 1-octene synthesized using a V-based Ziegler-Natta catalyst was studied as a function of the short chain branching content (SCBC) and the molar mass. Linear polyethylenes (LPE) were used as reference material. For the linear samples an increase in molar mass resul…
Two types of carboxybetaines and their corresponding cationic monomers and polymers are synthesized in this study. Comparing the chemical shifts of the methylene groups in the cationic monomers and carboxybetaines in both 1H- and 13C-NMR spectra reveal that the respective methylene groups are clearly distinguished fro…
The available data on the problem of hypothetical crystalline carbon nitride are considered. These involve the crystal structure, the nature of chemical bonding, and physical properties of carbon nitride of which the most interesting is its predicted high hardness comparable with that of diamond. The experiments aimed…
The main objective of the paper is the investigation of adiabatic shear band localized fracture phenomenon in inelastic solids during dynamic loading processes. This kind of fracture can occur as a result of an adiabatic shear band localization generally attributed to a plastic instability implied by microdamage and t…
Recent studies have demonstrated that addition of a small quantity of dibenzylidene sorbitol (DBS) to a molten polymer may result in a physical gel if conditions permit the DBS molecules to self-organize into a three-dimensional network composed of highly connected nanofibrils. If the polymer crystallizes, DBS may als…