Thermoplastic elastomers: structural and morphological aspects of ether-esteramide copolymers

Polyesteramide 6NT6 (I)-polytetramethylene ether glycol (II) copolymers, pptd. from dil. soln. were studied by small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) with variation of the II content. A comparison of the structural characteristics of these materials was made with those of I, which consists of -CO-p-C6H4CONH(CH2)6NHCO-p-C6H4CO2(CH2)6O- units. Chain folding is assumed as the crystn. mechanism for the low-II content copolymers, with possible inclusion of polyether segments within the I crystal lattice. WAXS data support the view of a weakening of the I cryst. packing in the equatorial planes as the reason for broadening of the diffraction peaks, for changes in their relative intensities, and for the increase in the equatorial interplanar distances in the high-II content samples. The annealing behavior was investigated

Complessi del cobalto (III) con il legante polimerico poli (4-vinilpiridina)

The preparation of a cobalt(IIT) complex with $Coen_2$ (en = ethylenediamine) units bound with two pyridine nitrogen atoms of two different polymeric chains of poly-(4-vynilpyridine) in trans position was performed. The obtained compound is insoluble in water as well as in the most usual organic solvents, while it has partial solubility in some others, such as dimethylsulfoxide. By elemental analysis it was found that for 12-13 average pyridine nitrogen atoms, one cobalt(III) atom is available

DOPING KINETICS OF POLYACETYLENE IN THE SHORT RANGE

La cinétique du dopage avec I2 de films de polyacétylène (PA), obtenus par la méthode de Shirakawa /1/, a été étudiée dans les premières minutes du contact entre le dopant et le PA en suivant la variation des propriétés électriques de conductivité et spectroscopique d'absorbance IR à 1400 cm-1 et à 1023 et 750 cm-1. Les données expérimentales ont mis en évidence l'existence, dans cet intervalle de temps, de au moins trois étapes de réaction caractérisées par des constantes cinétiques qui diffèrent par des ordres de grandeur. On a essayé d'élaborer un modèle cinétique du processus de dopage et on a calculé les valeurs des énergies d'activation.The kinetics of doping with iodine of Polyacetylene (PA) films, synthesized by the Shirakawa technique /1/, have been investigated by measuring the variation of electrical conductivity and IR absorbance at 1400, 1023 and 750 cm-1 within the time range of the first minute of doping. The experimental data suggest that the doping process occurs within at least three steps whose rate constants differ by orders of magnitude. An attempt is made to elaborate a kinetic model for the doping process and the activation energies are calculated

POTENTIAL ENERGY CALCULATIONS ON POLYACETYLENE

Nous présentons des résultats de calcul d'énergie potentielle d'une chaîne de polyacétylène isolée dans le vide en fonction du nombre de degrés de liberté rotatoire autour des liaisons chimiques simples dans la chaîne, de la grandeur de la barrière de potentiel de torsion, de la configuration cis et trans, de la géométrie moléculaire et des fonctions de potentiel de Van der Waals employées. On propose une conformation désordonnée qui s'écarte du plan pour l'isomère trans soit en conformation trans-planaire plutôt que trans-cisoidale. Pour l'isomère cis on trouve une conformation "gauche" hélicoïdale dans laquelle les doubles liaisons qui se trouvent en pas successif de l'hélice sont situées à 3,3 Å et peuvent établir des interactions π - π.The results are presented of the potential energy calculations performed on the isolated chain of polyacetylene, as a function of the number of rotational degrees of freedom allowed to the chain, of the barrier height to the bond rotation, of the cis and trans configuration, of the molecular geometrie and of the Van de Waals potential functions sets. The findings support the view of a conformation slightly distorted from planarity for the trans polymer, with possible conformational disorder within the chain, and of a "dilution effect" of cisoidal units within trans sequences for the trans-cisoidal conformation. For the cis polymer a "gauche" conformation is found to be likely the most stable one, with alignement of the double bonds belonging to succeeding helical turns whose distance is 3.3 Å, giving rise to π - π intramolecular interactions