Conductive properties of polymer diacrylates incorporating solutions of lithium salts: Part I. Solvent–polymer and salt–solvent interactions

Gels were prepared by 1,3-butanediol diacrylate (BDD) or tetraethylene glycol diacrylate (TEG) polymerisation (UV irradiation with about 1 wt.% of benzoin methyl ether as initiator) in the presence of gamma butyrolactone (BL) or BL/LiN(CF3SO2)2 (LiTFSI) solutions which were incorporated in the polymer network. For the diacrylate/BL gels, the determination of molar polarisabilities and the Raman spectroscopic study allow to show that there is no specific interaction between the solvent and the polymer. The evolution of the ionic conductivity with the gel composition is related to the volumetric fraction of the liquid phase in the gel. The maximum absorption capacity of the diacrylate network towards the liquid phase is determined assuming a “cubic-like” structure. In order to compare, in the second part of this paper, the conductivities of the “free” and incorporated liquid phases, a simplified conductivity model is presented for the liquid electrolytes. In this article, the conductivity study is focused on the BDD/BL/LiTFSI electrolytes.