Preparation and characterization of novel hybrid thermoplastic poly(ether urethane)/poly(vinylidene fluoride) elastomers and their application as solid polymer electrolytes

A comb-like polyether, poly(3-2-[2-(2-methoxyethoxy)ethoxy]ethoxymethyl-3′-methyloxetane) (PMEOX), was reacted with hexamethylene diisocyanate and extended with butanediol in a one-pot procedure to give novel thermoplastic elastomeric poly(ether urethane)s (TPEUs). The corresponding hybrid solid polymer electrolytes were fabricated through doping a mixture of TPEU and poly(vinylidene fluoride) with three kinds of lithium salts, LiClO₄, LiBF₄ and lithium trifluoromethanesulfonimide (LiTFSI), and were characterized using differential scanning calorimetry, thermogravimetric analysis and Fourier transform infrared spectroscopy. The ionic conductivity of the resulting polymer electrolytes was then assessed by means of AC impedance measurements, which reached 2.1 × 10^-4 S cm^-1 at 30 °C and 1.7 × 10^-3 S cm^-1 at 80 °C when LiTFSI was added at a ratio of O:Li = 20. These values can be further increased to 3.5 × 10-4 S cm-1 at 30 °C and 2.2 × 10^-3S cm^-1 at 80 °C by introducing nanosized SiO₂ particles into the polymer electrolytes.