Synthesis and ionic conductivity of mixed substituted polysiloxanes with oligoethyleneoxy and cyclic carbonate substituents

Abstract

New comb polysiloxanes with mixed substituents were synthesized by hydrosilylation of PMHS with 4-allyloxymethyl-[1,3]dioxolan-2-one and tri(ethylene glycol) allyl methyl ether (AMPEO 3 ). The effect of the incorporation of carbonate groups on ionic transport, viscosity and thermal properties has been investigated. When doped with lithium bis(trifluorosulfonyl) imide, LiTFSI, the mixed substituted polysiloxane polymers with varying carbonate content all exhibited conductivity higher than those for the polysiloxanes with pure carbonate or pure oligoethyleneoxy substituents. The maximum ambient conductivity in this series was 1.62 × 10 −4 S/cm, occurring for the polymer containing 8.5% polar carbonate groups at a doping level of EO/LiTFSI = 15. The impedance measurement results showed that polymers containing larger amounts of carbonate groups exhibited lower conductivity, probably because of their increased viscosity and higher glass transition temperature. The conduction mechanism for these new comb polymers obeys free volume theory, as indicated by conductivity data fit to the VTF equation.

Silicon-Containing Carbonates—Synthesis, Characterization, and Additive Effects for Silicon-Based Polymer Electrolytes

“…1 H and 13 C NMR was carried out on a Bruker AC300; 29 Si NMR was performed on a Varian Unity 500. Deuterated chloroform (CDCl 3 , 99.8%, Aldrich) was used as the solvent.…”

“…The product was recovered as a clear colorless liquid (yield= 79%). 1 29 Si-NMR (CDCl 3 ), δ(ppm) 20.7.…”

“…Further purification by distillation gave clear, colorless liquids which were analyzed by 1 H, 13 C, and 29 Si NMR. Typical NMR spectra (from compound 1) are shown in Fig.…”

“…Although significant research has concentrated on the development of polysiloxane-PEO copolymer structures, alternative polymer electrolytes structures have also been investigated [3][4][5][6][7][8][27][28][29]. For example, Wnek and coworkers [27] introduced carbonate groups onto the polysiloxane backbone in order to study them as potential polymer electrolytes.…”

“…Using a similar method, cyclic carbonate groups were also attached to cyclic siloxanes [28]. Recently, our group attached both PEO and carbonate side chains to a single polysiloxane backbone [29]. These copolymers showed increased conductivity when compared to polysiloxanes substituted exclusively with PEO side chains.…”