Synthesis and characterization of all‐conjugated copolymers of 3‐hexyl‐thiophene and EDOT by grignard metathesis polymerization

Random regioregular copolymers of 3‐hexylthiophene and 3,4‐ethylenedioxythiophene were synthesized by grignard metathesis polymerization. Soluble copolymers were obtained with a high degree of regioregularity and with a monomer ratio close to the feed ratio. A comparison between the optical properties and the thin film morphologies of these copolymers and poly(3‐hexylthiophene) is also presented. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Pd-catalyzed regiocontrolled Sonogashira and Suzuki cross-coupling reaction of 3,6-dihalogenoimidazo[1,2-a]pyridines: one-pot double-coupling approach

New and efficient regioselective Sonogashira and Suzuki-Miyaura palladium-catalyzed coupling reactions of 3,6-dihalogenoimidazo[1,2-a]pyridines followed by another cross-coupling has been successfully developed. Various solvents, palladium species and bases were tested. Scope and limitations of this regiocontrolled palladium-catalyzed reaction were investigated. The synthesis of 3,6-disubstituted imidazo[1,2-a]pyridine derivatives using one-pot regioselective double-coupling approach was developed. This procedure affords convergent syntheses of polysubstituted compounds in high yields in a very few steps.     

Rheological,morphological, and interfacial properties of compatibilized PLA/PBAT blends

The focus of this paper was to gain a true understanding of the impact of a multifunctional epoxide (Joncryl®;ADR-4368) on the interfacial properties of biopolymer blends based on poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT). The effect of Joncryl on the shear rheological, morphological, and interfacial properties of the blends was systematically investigated. For the deformed drop retraction experiments, different sandwich model systems (droplet/matrix), representing various scenarios of compatibilization, were prepared, aiming to probe the role of the epoxy-functionalized chains on the interface. The decrease of the interfacial tension in the modified/compatibilized PLA_PBAT and the formation of the PLA-Joncryl-PBAT copolymer were highlighted. A new relaxation peak relative to this copolymer was detected by the relaxation spectrum. Transient start-up shear and nonlinear stress relaxation experiments were carried out and confirmed the obtained results. In addition, the interface contribution was demonstrated using the Lee and Park model. The relaxation time increased with the amount of added Joncryl. Hence, the coexistence of chain extension/branching chains coupled to the PLA-Joncryl-PBAT copolymer formation had to be taken into account to explain the improved mechanical properties.     

Synthesis and Characterization of [1,2,4,6]Thiatriazino[2,3-a][1,3]benzimidazol-1(2H)-one and [1,3,5]Thiadiazino[3,4-a][1,3]benzimidazol-2-imine

Abstract

The reaction of thionyl chloride with amidines 2, derived from N-benzimidazol-2-yl imidates 1, leads to [1,2,4,6]thiatriazino[2,3-a][1,3]benzimidazol-1(2H)-one 3 in good yields. [1,3,5]Thiadiazino[3,4-a][1,3]benzimidazol-2-imine 4 was prepared by condensation of NaSCN with benzimidazol-2-yl imidate 1. The isolated compounds 3 and 4 were identified by spectroscopic methods including IR, ¹H NMR, and ¹³C NMR as well as elemental analyses and MS of 3d and 4b.

GRAPHICAL ABSTRACT      

Boundedness and Lyapunov function for a nonlinear system of hematopoietic stem cell dynamics

We investigate a system of nonlinear differential equations with distributed delays, arising from a model of hematopoietic stem cell dynamics. We state uniqueness of a global solution under a classical Lipschitz condition. Sufficient conditions for the global stability of the population are obtained, through the analysis of the asymptotic behavior of the trivial steady state and using a Lyapunov function. Finally, we give sufficient conditions for the unbounded proliferation of a given cell generation.     

Thermodynamic Properties of {NaCl-CsCl-LiCl}(aq) at T=298.15 K: Water Activities, Osmotic and Activity Coefficients

A hygrometric method has been used to measure water activities for the quaternary aqueous system NaCl-CsCl-LiCl-H₂O as a function of the solutes concentrations at T=298.15 K. The measurements were performed by measuring the diameter of solution droplets as a function of the surrounding relative humidity. The total ionic strength range covered in this study was about 0.6 to 6 mol?kg^?1 for different ionic strength fractions y of one of the three solutes ranging from y=1/3 to 1/2, whereas the constant ratio r of molalities of the two other solutes was fixed at unity. The osmotic coefficients of these aqueous mixtures were calculated over this ionic strength range. The obtained data were treated by the ECA I and ECA II rules, and the Pitzer and Kim, and Pitzer-Dinane models. The solute activity coefficients of components in the studied mixtures were also determined for different ionic strength fractions of the different solutes.     

Thermophysical properties of polypropylene/aluminum composites

This article is dedicated to the study of the thermal parameters of composite materials. A nonlinear least‐squares criterion is used on experimental transfer functions to identify the thermal conductivity and the diffusivity of aluminum‐polymer composite materials. The density measurements were achieved to deduce the specific heat and thereafter they were compared to values given by differential scanning calorimetry measurement. The thermal parameters of the composite material polypropylene/aluminum were investigated for the two different types of aluminum filler sizes. The experimental data were compared with several theoretical thermal conductivity prediction models. It was found that both the Agari and Bruggeman models provide a good estimation for thermal conductivity. The experimental values of both thermal conductivity and diffusivity have shown a better heat transport for the composite filled with large particles. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 722–732, 2004     

A differential equation approach to implicit sweeping processes

In this paper, we study an implicit version of the sweeping process. Based on methods of convex analysis, we prove the equivalence of the implicit sweeping process with a differential equation, which enables us to show the existence and uniqueness of the solution to the implicit sweeping process in a very general framework. Moreover, this equivalence allows us to give a characterization of nonsmooth Lyapunov pairs and invariance for implicit sweeping processes. The results of the paper are illustrated with two applications to quasistatic evolution variational inequalities and electrical circuits.