Materials Literature
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The influence of the terminal segment of hydrophobically modified ethoxylated urethane (HEUR) on the linear mechanical behavior is examined through the synthesis of perfluoroalkyl telechelic HEUR (defined as F-HEUR). A series of perfluoroalkyl-modified poly(oxyethylene) (POE) of molecular weight M n = 6000, 10 000, an…
We present the results of some film simulations of polyethylene (PE) on a coarse-grained lattice, which is termed as the second nearest neighbor diamond (2nnd) lattice. Monte Carlo simulations of PE melts have been performed on the 2nnd lattice by including short- and long-range interactions. Films can be obtained fro…
Three compounds of general formula (NBu 4 )[M II Ru III (ox) 3 ] have been synthesized; NBu 4 + stands for tetra- n -butylammonium, M for Mn, Fe, and Cu, and ox 2 - for the oxalate dianion. The X-ray powder patterns for the three derivatives have revealed that these compounds are isostructural with (NBu 4 )[Mn II Cr I…
The intramolecular cyclization of α-carboxyl, ω-amino heterodifunctional polystyrene was carried out to obtain cyclic polystyrene having an amide moiety in the main chain. The amide moiety was reduced with lithium aluminum hydride to give macrocyclic amine. The reactions of the macrocyclic amine with carboxylic-termin…
Two dicarboxylic acids were prepared by alkylation of 4-hydroxycinammic acid with 1,6-dibromohexane or 1,12-dibromododecane. The dichlorides of these dicarboxylic acids were polycondensed with mixtures of isosorbide and methylhydroquinone. All copolyesters then obtained showed nematic schlieren textures. Furthermore,…
Recent results on the effect of the nanocrystalline state on the mechanical, thermal, and magnetic properties and microscopic structure of metals and solid-phase compounds are reviewed. Basic methods for preparing compact nanocrystalline materials are briefly discussed. Size effects in such materials are discussed in…
The first high-temperature endotherm ( T 1 ) of polyurethane hard segment based on 4,4‘-diphenylmethane diisocyanate (MDI) and 1,4-butanediol (BD) was studied by differential scanning calorimetry (DSC). The materials contain 69% (w/w) of MDI and BD as the hard segment and hydroxyl-terminated cis -polybutadiene with nu…
Nonisothermal melt crystallization kinetics of PEDEKmK linked by meta-phenyl and biphenyl was investigated by differential scanning calorimetry (DSC). A convenient and reasonable kinetic approach was used to describe the nonisothermal melt crystallization behavior, and its applicability was verified when the modified…
The position operator (defined within Schroedinger representation as usual) becomes meaningless when the usual Born-von Karman periodic boundary conditions are adopted: this fact is at the root of the polarization problem. I show how to define the position expectation value by means of rather peculiar many-body (multi…
A nonlinear kinetic exclusion model is used to study osmosis and pressure driven flows through nearly single file pores such as antibiotic channels, aquaporins, zeolites and nanotubules. Two possible maxima in the steady state flux as a function of pore-solvent affinity are found. For small driving forces, the linear…
Carbon nanotubes can be functionalized by oxidation of HNO 3 or H 2 SO 4 −HNO 3 . The latter shows a higher capability in producing a high density of surface functional groups. These groups can act as specific nucleation sites for a well-dispersed deposition of Pt clusters on the surface of carbon nanotubes. These mod…
We have synthesized two classes of polyureas with mono- and bisazoaromatic groups in their main chains via reactions between isophorone diisocyanate and the corresponding diamines. Holographic gratings were fabricated on azoaromatic polyurea films prepared by spin-coating from solutions. The effect of high glass trans…
Polysulfonates with reactive pendant chloromethyl groups were synthesized by polyadditions of bisepoxides with disulfonyl chlorides. The polyaddition of bisphenol A diglycidyl ether (BPGE) with m-benzene disulfonyl chloride (m-BDSC) occurred in anisole without any catalyst at 130°C for 24 h. However, polymer with high…
Diacetylene-containing polyimides have been prepared by the oxidative coupling of new diethynyl diimide monomers. Condensation of various ethynyl-terminated amines with either 4,4‘-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) or pyromellitic dianhydride (PMDA) provided the monomers. Processability was enhance…
Ablation characteristics of silicone insulation were examined in an induced air combustion chamber and by thermogravimetric analysis. The rate of ablation increased with the combustion pressure. Although the flame temperature was less effective in increasing the ablation rate, the ablation rate below 1160 K was much s…
Aliphatic diols and dicarboxylic acids condense in hydrophobic solvents to form polyesters at 25–75°C when the solutions interface with an acidic hydrophilic phase. Certain aliphatic ω-hydroxy acids behave similarly. Rigorous removal of the by-produced water by distillation is unnecessary and examples are cited where…
Activity of a cellulosomal endoglucanase (endoglucanase E; EGE) from Clostridium thermocellum against two crystalline forms of cellulose was enhanced by combination with the cellulosome integrating protein (CipA), but CipA did not enhance EGE activity against amorphous cellulose, even though it was able to bind to it.…
A general high-yield synthetic route to the hexacoordinate silicon porphyrin dichloride complexes trans -(Por)SiCl 2 {Por = the dianions of octaethylporphyrin (OEP), tetraphenylporphyrin (TPP), and tetrakis( p -(trifluoromethyl)phenyl)porphyrin (TTFP)} is reported. Reacting (Por)SiCl 2 with SbF 3 and AgOTf produces th…
Conserved residues of the proteolytic domain of Escherichia coli protease Lon, putative members of the classic catalytic triad (H665, H667, D676, and D743) were identified by comparison of amino acid sequences of Lon proteases. Mutant enzymes containing substitutions D676N, D743N, H665Y, and H667Y were obtained by sit…
Homo- and copolymerizations of butadiene (BD) and styrene (St) with rare-earth metal catalysts, including the most active neodymium (Nd)-based catalysts, have been examined, and the cis-1,4 polymerization mechanism was investigated by the diad analysis of copolymers. Polymerization activity of BD was markedly affected…