Organisation in two series of low-dimensional polymer electrolytes with high ambient lithium salt conductivity

Abstract

The amphiphilic polymers poly[2,5,8,11,14-pentaoxapentadecamethylene(5-hexadecyloxy-1,3-phenylene)] I (abbrev. C16O5), its homologues C16On, n = 1–4, and its copolymers with C16O1 have been synthesised by two Williamson procedures. Method X gives polyether-esters; method Y gives pure polyethers. DSC, optical microscopy, small-to-wide angle X-ray diffraction and complex impedance spectroscopy have been used to investigate organisation and ionic conductivities of the C16On and the C16O5–C16O1 copolymer series and their complexes with LiClO₄ and LiBF₄. Four-component mixtures of the latter systems (polymers I) with polyoxytetramethylene–decamethylene copolymer (II) and an octadecyl-terminated ABA block copolymer (III) (interfacial stabiliser) (‘type D’ systems) gave high ambient conductivities (≥10⁻⁴ S cm⁻¹) with low temperature dependence. Highest conductivities (8 × 10⁻⁴ S cm⁻¹ at 20 °C) were observed with a type D system based upon C12C18O5X.