Synthesis of partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions

Partially fluorinated poly(arylene ether sulfone) multiblock copolymers bearing perfluorosulfonic functions (ps‐PES‐FPES), with ionic exchange capacity (IEC) ranging between 0.9 and 1.5 meq H⁺/g, are synthesized by regioselective bromination of partially fluorinated poly(arylene ether sulfone) multiblock copolymers (PES‐FPES), followed by Ullman coupling reaction with lithium 1,1,2,2‐tetrafluoro‐2‐(1,1,2,2‐tetrafluoro‐2‐iodoethoxy)ethanesulfonate. The PES‐FPES are prepared by aromatic nucleophilic substitution reaction by an original approach, that is, “one pot two reactions synthesis.” The chemical structures of polymers are analyzed by ¹H and ¹⁹F NMR spectroscopy. The resulted ionomers present two distinct glass transitions and α relaxations revealing phase separation between the hydrophilic and the hydrophobic domains. The phase separation is observed at much lower block lengths of ps‐PES‐FPES as compared with the literature. AFM and SANS observations supported the phase separation, the hydrophilic domains are well dispersed but the connectivity to each other depends on the ps‐PES block lengths. The thermomechanical behavior, the water up‐take, and the conductivity of the ps‐PES‐FPES membranes are compared with those of Nafion 117^® and randomly functionalized polysulfone (ps‐PES). Conductivities close or higher to those of Nafion 117^® are obtained. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1941–1956     

On the Existence of Solutions to Vector Quasivariational Inequalities and Quasicomplementarity Problems with Applications Break to Traffic Network Equilibria

For vector quasivariational inequalities involving multifunctions in topological vector spaces, an existence result is obtained without a monotonicity assumption and with a convergence assumption weaker than semicontinuity. A new type of quasivariational inequality is proposed. Applications to quasicomplementarity problems and traffic network equilibria are considered. In particular, definitions of weak and strong Wardrop equilibria are introduced for the case of multivalued cost functions.     

A Method for Establishing Optimality Conditions for a Nonsmooth Vector-Valued Minimax Problem

Using a method of uniform approximations, necessary and sufficient conditions for a nonsmooth constrained vector-valued minimax problem are established in terms of Mordukhovich subdifferentials.     

Stability radii of positive linear Volterra-Stieltjes equations

We study stability radii of linear Volterra-Stieltjes equations under multi-perturbations and affine perturbations. A lower and upper bound for the complex stability radius with respect to multi-perturbations are given. Furthermore, in some special cases concerning the structure matrices, the complex stability radius can precisely be computed via the associated transfer functions. Then, the class of positive linear Volterra-Stieltjes equations is studied in detail. It is shown that for this class, complex, real and positive stability radius under multi-perturbations or multi-affine perturbations coincide and can be computed by simple formulae expressed in terms of the system matrices. As direct consequences of the obtained results, we get some results on robust stability of positive linear integro-differential equations and of positive linear functional differential equations. To the best of our knowledge, most of the results of this paper are new.     

Improved synthesis of tocopherol fatty alcohols and analogs: microglial activation modulators

The synthesis of tocopherol fatty alcohols (TFAs), potent microglial activation modulators, was achieved via C-alkylation of trimethylhydroquinone. Several analogs, in particular water-soluble prodrugs, have been synthesized using a Wittig reaction and their antioxidant activities have been evaluated.     

Effects of physical aging on yielding kinetics of polycarbonate

The purpose of this work was to investigate the effects of physical aging on the kinetics of yielding in polycarbonate. PC samples were annealed over a wide range of aging times and temperatures. Both tensile and compressive tests were performed over various loading rates and temperatures to analyze the effects of aging time and aging temperature on yielding kinetics. Two grades of polycarbonate, Makrolon, of different molecular weights, PC-2608 (low M_w), and PC-3208 (high M_w), supplied by Bayer were analyzed. In unaged condition, PC is hard and tough, but after aging, it becomes more brittle. In terms of molecular movement, the yielding process is a thermally activated process involving inter- and intra-molecular motions. The time–temperature dependence of yielding behavior can be separated into two regions. Aging does not affect localized molecular motions of the β process during yielding. Physical aging in PC results in a slower jump rate of the main segments of macromolecules between two equilibrium positions. It reduces the flexibility of the macromolecules and thus, makes the polymer more brittle. Heat aging also causes a decrease of the entropy (ΔS) in polycarbonate, and this decrease is more important when the molecular weight is reduced. Increasing the annealing time and temperature results in a continuous reduction of ΔS. The rate of aging decreases with decreasing annealing temperature and below about 30 °C, no aging takes place. Annealing also strongly affects the excess of enthalpy in PC. However the effect of physical aging on yielding differs to that on enthalpy excess. The kinetics of yielding and aging processes in polycarbonate are also different. An increase in the strain rate does not have the same effect on the yield stress as an increase in the aging time by a same factor.     

Infine Functions, Nonsmooth Alternative Theorems and Vector Optimization Problems

In this paper we introduce a new notion of infine nonsmooth functions and give several characterizations of infineness property. We prove alternative theorems with mixed constraints (i.e., inequality and equality constraints) being described by invex-infine nonsmooth functions. We establish a necessary and sufficient condition for a solution of a vector optimization problem involving mixed constraints to be a properly efficient solution.     

S-Shaped composition dependence of excess thermodynamic quantities for cyclohexane mixtures with globular alkanes

Expansion coefficients , isothermal compressibilities, thermal pressure coefficients and heat capacities have been measured at 25°C for the cyclohexane+trans-decalin system. An S-shaped composition dependence, positivelnegative for highllow cyclohexane compositions is found for C _p ^E dV ^E /dT and the thermal expansion contribution to C _p ^E namely VT. The thermal motion contribution to C _p ^E , namely C _v is close to zero. The positive excursion of these mixing quantities at high cyclohexane content is anomalous. Correspondingly, the mixing quantity-VT deviates strongly in this region from the predicted equality with H ^E . The literature and this work show that all these excess quantities behave similarly for cyclohexane mixed with cyclooctane, methylcyclohexane and some highly branched alkanes. The unusual composition dependence of the thermodynamic quantities is consistent with order occurring when any large alkane molecule of globular shape is added to cyclohexane. This is speculatively associated with an interference by the globular alkane with the relatively free rotation of cyclohexane molecules.     

Synthesis, characterization and crystal structures of two polyphilic mesogenic compounds

Three homologous series of semi-perfluorinated liquid crystals: 4-(2,2,3,3,4,4,4-heptafluoro-butyloxycarbonyl)phenyl, 4-(2,2,3,3,4,4,5,5-octafluoropentyloxycarbonyl)phenyl and 4-(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyloxycarbonyl)phenyl 4-[(n-perfluoroalkyl)alkyloxy]benzoates have been synthesized. Their mesomorphic properties were studied by DSC, microscopic observation and X-ray diffraction. Their layer spacings are smaller than the molecular length (L). The ratio d_SA/L is about 0.7. The crystal structure of two derivatives of the first family have also been investigated. In both structures the molecules pack in smectic C-like sheets where neighbouring molecules are antiparallel, interacting through dipolar and van der Waals forces. The interactions between contiguous sheets, through the ends of perfluorinated chains are very weak. The X-ray diffraction results on the mesophases and on the crystalline structures of two compounds of the first family are compared. From this, we propose a model of the smectic phases with a zig-zag structure.     

Transpositions a etapes multiples d'epoxydes sesquiterpeniques—I : Action de l'acide formique sur l'epoxyde de cyperene. Correlation entre le cyperene et l'α-cedrene

Cyperene epoxide 2, on treatment with formic acid, gives about ten products of which the two major ones have been isolated and characterised. The allylic alcohol 3 is the product of an allylic rearrangement. The diol 5 is produced by a multistep rearrangement, the mechanism of which is remarkable in that the first elementary step cannot be concerted. The structure of the diol 5 has been confirmed by correlation with α-cedrene.