Structure and inter-phase stability in solvent-free low-dimensional polymer electrolytes with high lithium conductivity

Two Williamson procedures for the synthesis of the amphiphilic polymers poly[2,5,8,11,14-pentaoxapentadecamethylene(5-alkyloxy-1,3-phenylene)] I (abbrev. CmO5) are compared. Method X gives polyether-esters; method Y gives pure polyethers. In both, a dehydration reaction gives rise to CmO5-CmO1 copolymers. Two-phase systems of I with polyoxytetramethylene and polyoxytrimethylene copolymers (II) and LiBF₄ have been prepared with and without an interfacial stabiliser copolymer III. Highest and most stable conductivities (>5 × 10^-4 S cm^-1 at ambient) with low temperature dependence were observed with III, but I from method Y showed a tendency to phase separate at ambient.