Synthesis and Characterization of Heterocyclic Functionalized Polymers by Click Reaction: Preparation of Magnetic Nanocomposites and Studies on Their Thermal,Mechanical, Photophysical and Metal Ions Removal Properties

This work reports synthesis and characterization of heterocyclic functionalized polymers, poly(triazole-etherimidazole)s(PTAEI), from a dialkyne-terminated compound, 3-(4,5-bis(4-(propargyloxy)phenyl)-1H-imidazol-2-yl)-9-ethyl-9H-carbazole, by using click reaction. PTAEIs were characterized and their properties such as solubility, thermal, mechanical, photophysical and metal ions adsorption were investigated. These polymers had weight average molar masses(Mw) in the range of 19100-26700 g/mol, exhibited excellent solubility in polar aprotic solvents and formed low-colored flexible thin films by solution casting method. They exhibited good thermal stability with glass transition temperatures(Tg) between 160 °C and 211 °C and 10% weight loss temperatures(T10%) in the range of 308-426 °C. Nanocomposites of PTAEIs with epoxide-terminated Fe3O4 showed that strong interfacial interaction between inorganic particles and the polymer matrix contributed to the enhanced thermal and mechanical properties. The photoluminescence intensity of the PTAEIs increased and the spectra red shifted with increasing Fe3O4 content. The PTAEIs and nanocomposites were tested for their extraction capability of metal ions from aqueous solutions either individually or in the mixture.     

Synthesis of new vinyl ether functionalized silica for UV-patterning

We report a new ORganically MOdified SILicates (ORMOSILs) stable sol based on vinyl ether function which can be deposited as a layer and structured by mean of UV radiation through a mask or by direct laser writing. Silica matrix is synthesized by sol–gel process and organic network is formed by photopolymerization. One of the potential applications is the fabrication of integrated optical circuits. [2-(3,4 epoxycyclohexyl ethyltrimethoxysilane)] has already used for the fabrication of such devices and to develop microstructures on an organic substrate by cationic polymerization. Obtained results show some weakness such as an important contribution of OH and aliphatic CH groups to the attenuation at 1550 nm wavelength and low conversion rate of organic polymerization involving poor mechanical properties. This work treats on the design of a new generation of hybrid materials with a very high reactivity and low amount of groups involved in the attenuation. We have chosen vinyl ether function as reactive organic part for her highest polymerization rate via cationic way. The new synthesized molecule is 4-vinylether phenyltriethoxysilane. Sol–gel kinetic reactions were monitored by liquid ²⁹Si-NMR spectroscopy. In order to obtain the highest reactive multifunctional oligomers and the lowest OH groups, hydrolysis and polycondensation reactions were followed as a function of time, temperature and pH of the water involved in the hydrolysis conditions. Finally, we show the feasibility to microstructure films deposited with this sol.     

Mechanically changed band gap of single walled carbon nanotube: a third neighbor tight-binding approach

Analytical derivation of electronic band gap of Single Walled Carbon Nanotube (SWCNT) under a small percent of uniaxial and torsional strains is in this paper. Our approach is based on a kind of π-Tight Binding (π-TB) approximation which includes interactions of the second and the third neighbors of each carbon atom in addition to the nearest ones. Implementing the approach of this paper, yields more precise results than those of other researches.     

An Efficient and Green Procedure for Synthesis of Pyrrole Derivatives by Paal–Knorr Condensation Using Sodium Dodecyl Sulfate in Aqueous Micellar

A simple, economical, and green approach to the synthesis of N‐substituted pyrroles using sodium dodecyl sulfate as surfactant in water is described. The experiment protocol features simple operations, and the products are isolated in high to excellent yields (60–98%).     

On <Emphasis Type="Italic">α</Emphasis>-stability criteria of linear systems with multiple time delays

This paper deals with the α-stability for a class of linear systems with multiple delays. New sufficient conditions for exponential stability with a convergence rate are established based on Lyapunov functionals and the linear matrix inequality technique. Two numerical examples are provided to illustrate the effectiveness of the proposed results. Translated from Sovremennaya Matematika i Ee Prilozheniya (Contemporary Mathematics and Its Applications), Vol. 61, Optimal Control, 2008.     

Sulfuric Acid: A Mild Catalyst for the Regioselective Synthesis of 2-Substituted [1,2,4]Triazolo[5,1-b][1,3]thiazin-7-ones

Summary.  A facile and regioselective synthesis of 2-substituted [1,2,4]triazolo[5,1-b][1,3]thiazin-7-ones by action of sulfuric acid on (4H-[1,2,4]triazol-3-ylsulfanyl)-acrylic acids is described. Received January 23, 2001. Accepted (revised) May 7, 2001