Jean‐François LeNest

Correlation among transport properties in ionically conducting cross-linked networks

Abstract Examination of the quantitative correlation between the ionic conductivity and the dynamic mechanical properties of cross-linked polyether networks filled with an inorganic salt supports the assumption that mobile ions and chains segments need the same free volume fraction for their diffusion. The spin-spin relaxation time of the different nuclei belonging either to the macromolecular chains or to the ionic species exhibits the same free volume dependence. From the study of the conductivity variations with respect to salt concentration it is concluded that its dissociation is probably complete even at relatively high concentration.

DSC and solid state NMR characterization of hydroxyethylcellulose/polyether films

Thin solid films of hydroxyethylcellulose/oligoether were obtained by a grafting reaction of HEC with diisocyanates, and were then characterized by DSC, FTIR, NMR and complex impedance techniques. The transparency of these films in the visible range of the electromagnetic spectrum, the low T g , the good chain mobility and ionic conductivity of 8.8 x 10 -4 Scm -1 at 333 K, show that they can be used as solid electrolytes in electrochromic devices.

Cellulose derivatives as solid electrolyte matrixes

Cellulose derivatives like hydroxyethylcellulose (HEC) and carboxymethylcellulose (CMC) were submitted to the graftization reactions. The samples of HEC were grafted with monoisocyanate of polypropylene oxide) (MPPO) and different diisocyanates of poly(ethylene oxide) (DPEO) and polypropylene oxide) (DPPO) in the presence of LiClO 4 . CMC was grafted with MPPO. These polyssacharides based samples were characterized by IR, NMR and thermal analysis (DSC and TGA). The samples of grafted polyssacharides derivatives showed glass transition temperatures (Tg) of -40°C for HEC/MPPO, -33°C for HEC/DPEO, -10°C for HEC/DPPO and 24°C for CMC/MPPO. The ionic conductivities of all samples were about 10 -7 -10 -6 S/cm at room temperature. The sample of CMC/MPPO presented conductivity value similar to HEC/DPPO but does not exhibit film-forming characteristic indicating its use as solid polymer electrolytes only in the pellet form.

Correlation between ionic conductivity and7Li-NMR of polyether-polyurethane networks containing lithium perchlorate

SummaryThe effect of temperature on the ionic conductivity and the7Li NME line width of a polyether-polyurethane network containing lithium perchlorate was studied. A treatment of the results based on free-volume principles yielded a linear correlation between the logarithm of the reduced conductivity, бT /бT0, and the logarithm of the reduced7Li NMR line width, δT/δT0, for a given reference temperature, To=323 K.

Ion-Containing Networks: Recent Results Concerning Transport Properties

Various types of networks containing either an added salt or an ionisable function were thoroughly characterised in order to gain a better understanding of the interactions between ions and polymer segments and of the electrochemical properties displayed as a function of the network structure and the electrolyte.

Ion-Containing Networks: Structural Modifications Induced by Lithium Ions

Polyether-urethane networks containing lithium Perchlorate were submitted to swelling and proton spin-spin relaxation rate measurements to gain a better understanding of the interactions between the salt and the polyether chains. A model is proposed to account for the present results and previous data.

Ethylene polymerisation with new catalysts: Et2AICI-organotitanium compounds

SummaryA brief kinetic study is reported of the polymerisation of ethylene catalysed by four aluminium-titanium chloro-organic complexes, three of which are new. These systems proved efficient both in terms of polymerisation rate and of the linearity of the high polymers obtained. A comparison is made with previous work in this field.